Как проверить конденсатор мультиметром на работоспособность

Как проверить конденсатор мультиметром на работоспособность – вопрос, возникающий у всех радиолюбителей и людей, которые любят заниматься паянием электрических схем разной сложности. Сделать это довольно просто, если знать некоторые тонкости.

Под тестером принято понимать стрелочные аппараты, работающие на аналоговом принципе. Мультиметр – это цифровой прибор, имеющие экран, где и отображается вся информация. На проверку можно отправить только конденсаторы, имеющие большую емкость, но узнать саму емкость невозможно, даже примерно. Если конденсатор рабочий, стрелка прибора вначале слегка отклонится, а потом начнет опускаться до бесконечности.

В статье подробны подробным образом рассмотрены все вопросы проверки конденсаторов на работоспособность. Бонусом служат ролик и подробная статься на эту тему.

Как проверить конденсатор с помощью приборов.

Как проверить конденсатор мультиметром

По сути ремонт любой радиоэлектронной аппаратуры сводится к поиску и замене неисправных деталей. И, возможно, вы удивитесь тому, насколько часто выходят из строя такие, казалось бы, простые компоненты как конденсаторы.

В то время как нежные диоды, чувствительные транзисторы и сложные микросхемы остаются целыми и невредимыми. Типичные неисправности конденсаторов:

• КЗ между обкладками. Как правило, это следствие механического повреждения, перегрева или превышения рабочего напряжения (пробой). Самый простой случай, т.к. легко выявляется любым мультиметром в режиме прозвонки;
• внутренний обрыв с полной потерей емкости (вот почему нельзя коротить отвертками). В случае с конденсаторами большой емкости этот дефект достаточно просто диагностируется. Выявление обрыва у мелких кондеров (менее 500 пФ) является довольно трудоемкой задачей и осуществляется только при помощи спец. приборов;
• частичная потеря емкости. Для электролитических конденсаторов потеря емкости с годами практически неизбежна, однако это не всегда приводит к неисправности устройства (но может ухудшать его характеристики). Керамические, пленочные и прочие с твердым диэлектриком, как правило, более стабильны, но могут потерять емкость в результате механического повреждения;
• слишком низкое сопротивление утечки (конденсатор “не держит” заряд). В основном это свойственно электролитическим конденсаторам. Хотя танталовые в этом плане очень хороши;
• слишком большое эквивалентное последовательное сопротивление (ЕПС или ESR). Проблема по большей части касается “электролитов” и проявляется только при работе с высокочастотными или импульсными токами.

Существует масса способов как проверить конденсатор мультиметром на работоспособность.

Проверка конденсатора мультиметром

Для начала давайте разберемся, что это за устройство, из чего он состоит, и какие виды конденсаторов существуют. Конденсатор представляет собой устройство, которое способно накапливать электрический заряд. Внутри он состоит из двух металлических пластин параллельных между собой. Между пластинами расположен диэлектрик (прокладка). Чем больше пластины, тем соответственно больший заряд они могут накапливать.

Существует два вида конденсаторов:

1. 1) полярные;
2. 2) неполярные.

Как можно догадаться по названию полярные имеют полярность (плюс и минус) и подключаются к электронным схемам со строгим соблюдением полярность: плюс к плюсу, минус к минусу. В противном случае конденсатор может выйти из строя. Все полярные конденсаторы – электролитические. Бывают как с твердым, так и с жидким электролитом. Емкость колеблется в диапазоне 0.1 ÷ 100000 мкФ. Неполярные конденсаторы без разницы как подключать или впаивать в схему, у них нет плюса или минуса. В неполярных кондерах диэлектрическим материалом является бумага, керамика, слюда, стекло.

Их емкость не очень большая колеблется в приделах от несколько пФ (пикофарад) до единиц мкФ (микрофарад). Друзья некоторые из Вас могут задаться вопросом, зачем эта ненужная информация? Какая разница полярный-неполярный? Все это влияет на методику измерений. И перед тем как проверить конденсатор мультиметром нужно понимать, какой именно тип устройства перед нами находится.

Как проверить конденсатор с помощью приборов

Прежде всего, выполняется внешний осмотр конденсатора на предмет трещин и вздутия. Нередко причиной неисправности является внутренние повреждения электролитов, что в свою очередь приводит к увеличению давления внутри корпуса, и как следствие вздутие оболочки. Если конденсатор с виду цел, то без специальных приборов трудно сказать работоспособный он или нет. Поэтому в этом случае выполняется проверка конденсатора мультиметром. Этот простой прибор позволит нам определить емкость конденсатора и наличие обрывов внутри.

Различные конденсаторы.

Перед тем, как приступить к проверке, нужно определиться какого рода конденсатор находится перед вами: полярный или неполярный. Помните, выше я писал, что это будет важно при измерениях. Так вот при выполнении проверки полярных конденсаторов нужно соблюдать полярность и подключать щупы к ним соответственно: плюсовой к ножке «+», а минусовой к ножке «-». При проверке неполярных «кондеров» полярность в подключении соблюдать не нужно, однако здесь есть одна особенность на которую нужно обращать внимание. Для проверки целостности кондера переключатель мультиметра нужно выставить на отметку 2 МОм.

Если будет меньше, то на дисплее будет отображаться – «1» (единица), можно ложно подумать что конденсатор неисправен. Переключатель мультиметра устанавливаем в секторе измерения сопротивления (режим омметра). Режим сопротивления даст нам понять есть ли внутри кондера обрыв или короткое замыкание. Для этого выставляем переключатель на отметку 2 МОм и касаемся щупами выводов конденсатора. Как только щупы будут подключены, на дисплее можно увидеть стремительно растущее сопротивление.

Почему так происходит

Почему на дисплее можно наблюдать «плавающие значения сопротивления»? Все дело в том, что при касании щупами выводов к конденсатору прикладывается постоянное напряжение (батарейка прибора) – он начинает заряжаться. Чем дольше мы держим щупы, тем больше конденсатор заряжается, и сопротивление плавно увеличивается. Скорость заряда напрямую зависит от емкости. Спустя время конденсатор зарядится и его сопротивление будет равно «бесконечности», а на дисплее мультиметра мы увидим «1». Это показатель того что конденсатор исправен.

Не все удается передать фотографиями, но для экземпляра 5.6 мкФ сопротивление стартует с 200 кОм и плавно растет, пока не перевалит отметку в 2 МОм. Длится весь процесс, примерно 10 сек. Со вторым конденсатором номиналом 3.3 мкФ происходит все аналогично. Начинает заряжаться, сопротивление растет, как только показания превысят отметку 2 МОм на дисплее можно увидеть «1» что соответствует «бесконечности». По времени процесс длится меньше, примерно 5 сек.

Материал по теме: Как проверить варистор мультиметром.

Измерение емкости конденсатора мультиметром и специальными приборами

Некоторые мультиметры имеют функцию измерения емкости. Взять хотя бы эти распространенные модели: M890D, AM-1083, DT9205A, UT139C и т.д.Также в продаже есть цифровые измерители емкости, например, XC6013L или A6013L. С помощью любого из этих приборов можно не только узнать точную емкость конденсатора, но и убедиться в отсутствии короткого замыкания между обкладками или внутреннего обрыва одного из выводов.

Некоторые производители даже уверяют, что их мультиметры способны проверить емкость конденсатора не выпаивая его с платы. Что, конечно же, противоречит здравому смыслу.

К сожалению, проверка конденсатора мультиметром не поможет определить такие наиважнейшие параметры, как ток утечки и эквивалентное последовательное сопротивление (ESR). Их измерить только с помощью специализированных тестеров. Например, с помощью весьма недорогого LC-метра.

Измерение емкости конденсатора мультиметром и специальными приборами.

Проверка на короткое замыкание

Есть три способа сделать это.

Способ №1: определение КЗ в режиме прозвонки

Как прозванивать конденсаторы мультиметром? Нужно включить мультиметр в режим прозвонки или измерения сопротивления и приложить щупы к выводам конденсатора. В зависимости от емкости мультиметр либо сразу же покажет бесконечное сопротивление, либо через какое-то время (от нескольких секунд до десятков секунд). Если же прибор постоянно пищит в режиме прозвонки (или показывает очень низкое сопротивление в режиме измерения сопротивления), то конденсатор можно смело выкидывать.

Интересный материал для ознакомления: что такое вариасторы.

Способ №2: определение КЗ конденсатора с помощью светодиода и батарейки

Если нет мультиметра (и даже старой советской “цешки” нету), то можно попробовать подключить светодиод или лампочку к батарейке через исследуемый конденсатор. Т.к. исправный конденсатор имеет ооочень большое сопротивление постоянному току, лампочка гореть не должна.

Хотя, если емкость конденсатора достаточно большая, лампочка может вспыхнуть на короткое время (пока конденсатор не зарядится). Если же светодиод горит постоянно, конденсатор 100% неисправен. Если при проверке конденсатора наблюдается эффект постепенного роста сопротивления вплоть до бесконечности (ну или светодиод на какое-то время вспыхивает и гаснет) то конденсатор совершенно точно имеет какую-то емкость.

Следовательно, проверку на обрыв можно не делать.

Способ №3: проверка конденсатора лампочкой на 220В

Подходит для высоковольтных неполярных конденсаторов (например, пусковые конденсаторы из стиральных машин, насосов, различных станков и т.п.). Все что нужно сделать – просто подключить лампу накаливания небольшой мощности (25-40 Вт) через конденсатор.

Проверка на отсутствие внутреннего обрыва

Обрыв – распространенный дефект конденсатора, при котором один из его электродов теряет электрическое соединение с обкладкой и фактически превращается в короткий, ни с чем не соединенный (висящий в воздухе), проводник. Чаще всего обрыв происходит из-за превышения рабочего напряжения конденсатора. Этим грешат не только электролитические конденсаторы, но и специальные помехоподавляющие конденсаторы типа Y (они, кстати говоря, специально так спроектированы, чтобы уходить в отрыв, а не в КЗ).

Конденсатор с внутренним обрывом внешне ничем не отличается от исправного, кроме случаев, когда ножку физически оторвали от корпуса. Разумеется, в случае отрыва одного из выводов от обкладки конденсатора, емкость такого конденсатора становится равной нулю. Поэтому суть проверки на обрыв состоит в том, чтобы уловить хоть малейшие признаки наличия емкости у проверяемого конденсатора.

Таблица характеристик надежности конденсаторов.

Способ №1: исключение обрыва через звуковой сигнал в режиме прозвонки

Включить мультиметр в режим прозвонки, прикоснуться щупами к выводам конденсатора и в этот момент мультиметр должен издать непродолжительный писк. Иногда звук настолько короткий (зависит от емкости конденсатора), что больше похож на щелчок и нужно очень постараться, чтобы его услышать. Небольшой лайфхак: чтобы увеличить продолжительность звукового сигнала при прозвонке совсем маленьких конденсаторов, нужно предварительно зарядить их отрицательным напряжением, приложив щупы мультиметра в обратном порядке.

Тогда при последующей прозвонке мультиметру сначала придется перезарядить конденсатор от какого-то отрицательного напряжения до нуля, и только потом – от нуля до момента отключения пищалки. На все это уйдет значительно больше времени, а значит сигнал будет звучать дольше и его проще будет расслышать. Из своей практике могу сказать, что с помощью уловки, описанной выше, мне удавалось уловить реакцию мультиметра на конденсатор емкостью всего лишь 0.1 мкФ (или 100 нФ)!

Способ №2: увеличение сопротивления постоянному току как признак отсутствия обрыва

Если предыдущий способ не помог и вообще не понятно, как проверить конденсатор тестером, то вот вам более чувствительный метод проверки. Необходимо переключить мультиметр в режим измерения сопротивления. Выбрать максимально доступный предел измерения (20 или лучше 200 МОм). Приложить щупы к выводам конденсатора и наблюдать за показаниями мультиметра.

По мере заряда конденсатора от внутреннего источника мультиметра, его сопротивление будет постоянно расти до тех пор, пока не выйдет за пределы диапазона измерения. Если такой эффект наблюдается, значит обрыва нет. Кстати говоря, может так оказаться, что рост сопротивления остановится на значении от единиц до пары десятков МОм – для конденсаторов с жидким электролитом (кроме танталовых) это абсолютно нормально. Для остальных конденсаторов сопротивление утечки должно быть больше, как минимум, на порядок.

При измерении таких высоких сопротивлений необходимо следить за тем, чтобы не касаться пальцами сразу обоих измерительных щупов. Иначе сопротивление кожи внесет свои коррективы и исказит все результаты. С помощью измерения сопротивления на пределе 200 МОм мне удавалось однозначно определить отсутствие обрыва в конденсаторах емкостью всего 0.001 мкФ (или 1000 пФ).

Способ №3: измерение остаточного напряжения для исключения внутреннего обрыва

Это самый чувствительный способ, позволяющий убедиться в отсутствии обрыва конденсатора даже тогда, когда все предыдущие способы не помогли. Берется мультиметр в режиме прозвонки или в режиме измерения сопротивления (не важно в каком диапазоне) и на пару секунд прикладываем щупы к выводам испытуемого конденсатора. В этот момент конденсатор зарядится от мультиметра до какого-то небольшого напряжения (обычно 2.8 В).

Затем мы быстро переключаем мультиметр в режим измерения постоянного напряжения на самом чувствительном диапазоне и, не мешкая слишком долго, снова прикладываем щупы к конденсатору, чтобы измерить на нем напряжение. Если у кондера есть хоть какая-нибудь вразумительная емкость, то мультиметр успеет показать напряжение, до которого был заряжен конденсатор. Этим способом мне удавалось с помощью обычного цифрового мультиметра M890D отловить емкость вплоть до 470 пФ (0.00047 мкФ)!

Это очень маленькая емкость. Вообще говоря, это наиболее эффективный метод прозвонки конденсаторов. Таким способ можно проверять кондеры любой емкости – от малюсеньких до самых больших, а также любого типа – полярные, неполярные, электролитические, пленочные, керамические, оксидные, воздушные, металло-бумажные и т.д. Правда, если конденсатор имеет совсем маленькую емкость, до 470 пФ, то, увы, проверить его на обрыв без специального прибора, вроде упомянутого ранее LC-метра, никак не получится.

Более подробно о проверке конденсаторов можно узнать  прочитав статью проверка конденсаторов  Если у вас остались вопросы, можно задать их в комментариях на сайте. Также в нашей группе ВК можно задавать вопросы и получать на них подробные ответы от профессионалов.

Чтобы подписаться на группу, вам необходимо будет перейти по следующей ссылке: https://vк.coм/еlеctroinfonеt. В завершение статьи хочу выразить благодарность источникам, откуда мы черпали информацию:

www.electro-shema.ru

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90000 How to Test a Capacitor by Digital & Analog Multimeter 90001 90002 90003 6 Ways to Check a Capacitor by using DMM & AMM (AVO) 90004 90005 90006 In most electrical and electronics troubleshooting and repairing works, we face a common trouble that 90003 how to test and check a capacitor? 90004 90003 Is it good, bad (dead), short or open? 90004 90011 90006 Here, we can check a capacitor with analog (AVO meter i.e. Ampere, Voltage, Ohm meter) as well as digital multi meter either it is in good condition or should we replace it with a new one.. 90011 90006 Note: To find the value of Capacitance, you need a digital meter with Capacitance measuring features. 90011 90006 90017 90017 90011 90006 Below are five (6) methods to 90003 check & test that a Capacitor is Good, Bad, Open, Dead, or Short 90004. 90011 90006 Related Posts: 90011 90006 90003 Method 1. 90004 90011 90030 90003 Traditional Method to Test & Check a Capacitor 90004 90033 90006 Note: Not Recommended for everyone but professionals only. Please be careful to do this practice as it is dangerous.Make sure that you are a professional electrical engineer / electrician (you really know that what are you doing or check the warnings before applying this method) and there are no other options to check the capacitor because serious damages may occur during this practice). If you are sure, go ahead, otherwise, go to method 2 — 6 as alternative methods to a capacitor. 90011 90006 Suppose you want to check the Capacitor (for example, fan capacitors, room air cooler capacitors or tinny capacitors in a circuit board / PCB etc.) 90011 90006 90003 Warning & recommendations for testing a capacitor by method 1. 90004 90011 90006 For better safety, use 24V DC instead of 230V AC. In case of absence of the desired DC 24V system, you may use 220-224V AC, but you have to make a serial of resistors (say 1kΩ ~ 10kΩ, 5 ~ 50Watts) to connect between capacitor and 230V AC supply.So that, it will reduce the charging and discharging current. Here is the step by step tutorial that how may you check a capacitor by this method. 90011 90044 90045 Disconnect the suspected capacitor from the power supply or make sure at least one lead of the capacitor is disconnected.90046 90045 Make sure that the capacitor is fully discharged. 90046 90045 Connect two separate leads to the capacitor terminals. (Optional) 90046 90045 Now safely connect these leads to 230 V AC Supply for a very short period (about 1-4 Sec) [or for a short time where the Voltage rise to 63.2% of the Source Voltage]. 90046 90045 Remove safety leads from the 230 V AC Supply. 90046 90045 Now short the capacitor terminals (Please be careful to do that and make sure that you have wear safety goggles) 90046 90045 If it makes a strong spark, then the 90003 capacitor is good 90004.90046 90045 If it makes a weak spark, then it is a 90003 bad capacitor 90004 and change it immediately with a new one. 90046 90065 90006 90067 90067 90011 90006 Related Posts: 90011 90006 90003 Method 2. 90004 90011 90030 90003 Test a Capacitor By Analog Multimeter 90004 90033 90006 To check a capacitor by AVO (Ampere, voltage, Ohm Meter), follow the following steps. 90011 90044 90045 Make sure the suspected capacitor is fully discharged. 90046 90045 Take an AVO meter. 90046 90045 Select analog meter on OHM (Always, select the higher range of Ohms).90046 90045 Connect the Meter leads to the Capacitor terminals. 90046 90045 Note The reading and Compare with the following results. 90046 90045 90003 Short Capacitors 90004: Shorted Capacitor will show very low Resistance. 90046 90045 90003 Open Capacitors 90004: An Open Capacitor will not show any movement (Deflection) on OHM meter Screen. 90046 90045 90003 Good Capacitors 90004: Initially, it will show low resistance, and then gradually increases toward the infinite. It means that Capacitor is in Good Condition.90046 90065 90006 90107 90107 90011 90006 90003 Method 3. 90004 90011 90030 90003 Check a Capacitor By a Digital Multimeter 90004 90033 90006 To test a capacitor by DMM (Digital Multimeter), follow the steps given below. 90011 90044 90045 Make sure the capacitor is discharged. 90046 90045 Set the meter on Ohm range (Set it at lease 1000Ohm = 1k). 90046 90045 Connect the meter leads to the capacitor terminals. 90046 90045 Digital meter will show some numbers for a second. Note the reading.90046 90045 And then immediately it will return to the OL (Open Line). Every attempt of Step 2 will show the same result as was in step 4 and Step 5. It’s mean that 90003 Capacitor is in Good Condition 90004. 90046 90045 If there is no Change, then 90003 Capacitor is dead 90004. 90046 90065 90006 90139 90139 90011 90006 You may Also check: 90011 90006 90003 Method 4. 90004 90011 90030 90003 Checking Capacitor By Multimeter in the capacitance Mode 90004 90033 90006 Note: You can do this test with a multimeter if you have a Capacitance meter or you have a multimeter with a feature to test the capacitance.Also, this method is good to test the tiny capacitors as well. To this test, rotate the multimeter knob to the capacitance mode. 90011 90044 90045 Make sure the capacitor is fully discharged. 90046 90045 Remove the capacitors from board or circuit. 90046 90045 Now Select «Capacitance» on your multimeter. 90046 90045 Now connect the capacitor terminal to the multimeter leads. 90046 90045 If the reading is near to the actual value of the capacitor (i.e. the printed value on the Capacitor container box).90046 90045 Then the capacitor is in good condition. (Note that the reading may be less than the actual value of the capacitor (the printed value on the Capacitor container box). 90046 90045 If you read a significantly lower capacitance or none at all, then capacitor is dead and you should change it. 90168 90168 90046 90065 90006 Related Posts: 90011 90006 90003 Method 5. 90004 90011 90030 90003 Testing a Capacitor By Simple Voltmeter. 90004 90033 90044 90045 Make sure to disconnect a single lead (no worries if Positive (long) or negative (short)) of the capacitor from circuit (You may fully disconnect as well when needed) 90046 90045 Check the capacitor voltage rating printed on it (As shown in our below example where is the voltage = 16V) 90046 90045 Now charge this capacitor for a few second to the rated (not to the exact value but less than that i.e. charge a 16V capacitor with 9V battery) voltage. Make sure to connect the positive (red) lead of the voltage source to the positive lead (long) of the capacitor and negative to negative. If you are unable to find it or not sure, here is the tutorial how to find the negative and positive terminal of a capacitor. 90046 90045 Set the value of voltmeter to the DC and connect the Capacitor to the voltmeter by connecting the positive wire of battery to the positive lead of capacitor and negative to negative.90046 90045 Note the initial voltage reading in the voltmeter. If it is close to the supplied voltage you given to the capacitor, the Capacitor in in Good condition. If it shows far little reading, Capacitor is dead then. note that the voltmeter will show the reading for very short term as the capacitor will discharge its volt in the voltmeter and it is normal. 90046 90065 90006 90195 90195 90011 90006 90011 90006 Related Posts: 90011 90006 90003 Method 6. 90004 90011 90030 90003 Find the capacitor value by measuring the value of Time Constant 90004 90033 90006 We can find the value of a capacitor by measuring the Time constant ( TC or τ = Tau) if the value of capacitance of a capacitor is known in microfarad (symbolized μF) printed on it i.e. the capacitor is not blown and burnt at all. 90011 90006 In brief, the time taken by a capacitor to charge about 63.2% of the applied voltage when charges through a known value of resistor is called Time Constant of Capacitor (TC or τ = Tau) and can be calculated via: 90011 90006 90003 τ = RxC 90004 90011 90006 Where: 90011 90220 90045 R = Known Resistor 90046 90045 C = Value of Capacitance 90046 90045 τ = TC or τ = Tau (Time Constant) 90046 90227 90006 For instance, if the supply voltage is 90003 9V 90004, then 90003 63.2% 90004 of this is around 90003 5.7V 90004. 90011 90006 Now, let see how to find the value of a capacitor by measuring the Time Constant. 90011 90006 Make sure to disconnect as well as discharge the capacitor from the board. 90011 90006 Connect a known value of resistance (e.g 5-10kΩ Resistor) in series with the capacitor. 90011 90006 Apply the known value of supply voltage. (E.g 12V or 9V) to the capacitor connected in series with 10kΩ resistor. 90011 90006 Now, measure the time taken for the capacitor to charge about the 63.2% of the applied voltage. For instance, if the supply voltage is 9V, then 63.2% of this is around 5.7V. 90011 90006 From the value of given resistor and measured time, calculate the value of capacitance by Time Content formula i.e. 90003 τ = TC 90004 or 90003 τ = Tau (Time Constant) 90004. 90011 90006 Now compare the calculated value of capacitance with the value of capacitor printed to it. 90011 90006 If they are same or nearly equal, The capacitor is in good condition. If you find a noticeable difference in both values, time to change the capacitor as it is not function well.90011 90006 The discharge time can also be calculated. In this case, the time take by the capacitor to discharge to 36.8% of the peak voltage can be measured. 90011 90006 90003 Good to know 90004: The time taken by a capacitor to discharge about 36.8% of the peak value of the applied voltage can be also measured. The discharge time can be used as same in the formula to find the value of capacitor. 90011 90006 90263 90263 90011 90006 Related Posts: 90011.90000 Capacitors 101 — iFixit 90001 90002 Here is a bit of the dry stuff, just to help understanding what a capacitor is and generally does. A capacitor is a small (most of the time) electrical / electronics component on most circuit boards that can perform various functions. When a capacitor is placed in a circuit with an active current, electrons from the negative side build up on the closest plate. The negative flows to the positive-that is why the negative is the active lead, although many capacitors are not polarized.Once the plate can no longer hold them, they are forced past the dielectric and onto the other plate, thus displacing the electrons back into the circuit. This is called the discharge. Electrical components are very sensitive to voltage swings, and as such a power spike can kill those expensive parts. Capacitors condition DC voltage to other components and thus provide a steady power supply. AC current is rectified by diodes, so instead of AC, there are pulses of DC from zero volts to peak. When a capacitor from the power line is connected to ground and the DC will not pass, but as the pulse fills up the cap, it reduces the current flow and the effective voltage.While the feed voltage goes down to zero, the capacitor begins to leak out its contents, this will smooth the output voltage and current. Therefore a capacitor is placed inline to a component, allowing for absorption of spikes and supplementing valleys, this, in turn, keeps a constant power supply to the component. 90003 90002 There is a multitude of different types of capacitors. They are often used differently in circuits. The all too familiar round tin can style capacitors are usually electrolytic capacitors.They are made with one or two sheets of metal, separated by a dielectric. The dielectric can be air (simplest capacitor) or other non-conductive materials. The metal plate foils, separated by the dielectric, are then rolled up similar to a Fruit Roll-up, and placed into the can. These work great for bulk filtering, but they are not very efficient at high frequencies. 90003 90002 Here is a capacitor that some may still remember from the old radio days. It is a multi-section can capacitor. This particular one is a quad (4) section capacitor.All that means is, that there are four separate capacitors, with different values, contained in one can. 90003 90002 Ceramic disc capacitors are ideal for higher frequencies but are not good to do bulk filtering because ceramic disc capacitors get to big in size for higher values ​​of capacitance. In circuits where it is vital to keep a voltage source stable, there is usually a large electrolytic capacitor in parallel with a ceramic disc capacitor. The electrolytic will do most of the work, whereas the small ceramic disc capacitor will filter off the high frequency that the big electrolytic capacitor misses.90003 90002 Then there are tantalum capacitors. These are small, but have a greater capacitance in relation to their size than ceramic disk capacitors. These are more costly, but find plenty of use on the circuit boards of small electronic devices. 90003 90002 Although non-polar, old paper capacitors had black bands at one end. The black band indicated which end of the paper capacitor had some metal foil (which acted as a shield). The end with the metal foil was connected to the ground (or lowest voltage).The main purpose of the foil shield was to make the paper capacitor last longer. 90003 90002 Here is the one that we are most likely interested in the most, when it comes to iDevices. These are very small in comparison to the before listed capacitors. They are the Surface Mount Device (SMD) caps. Even so they are miniature in size compared to the previous capacitors, the function is still the same. One of the importance, besides the values ​​of these capacitors, is their «package». There is a standardization for the size of these components, i.e. package 0201 — 0.6 mm x 0.3 mm (0.02 «x 0.01»). The package size for the ceramic SMD capacitors follows the same package for SMD resistors. This makes it almost impossible to determine if it is a capacitor or a resistor by visualization. Here is a good description of the individual size based on package numbers. 90003 90002 Determining the value a capacitor has can be accomplished in a few ways. Number one, of course, is a marking on the capacitor itself. 90003 90002 This particular capacitor has a capacitance of 220μF (micro farad) with a tolerance of 20%.This means that is could be anywhere between 176μF and 264μF. It has a voltage rating of 160V. The arrangement of the leads all show that it is a radial capacitor. Both leads exit on one side versus an axial arrangement where one lead exits from either side of the capacitors body. Also, the arrowed stripe on the side of the capacitor indicates the polarity, the arrows are pointing towards the 90019 negative pin 90020. 90003 90002 Now the main question here is, how to check a capacitor to see if it needs replacing.90003 90002 To perform a check on a capacitor while it is still installed in a circuit, an ESR meter will be necessary. If the capacitor is removed from the circuit then a multimeter set as an ohm meter can be used, 90025 but only to perform an all-or-nothing test 90026. This test will only show if the capacitor is completely dead, or not. It will 90025 not 90026 determine if the capacitor is in good or poor condition. To determine if a capacitor is functioning at the right value (capacitance), a capacitor tester will be necessary.Of course, this also holds true to determine the value of an unknown capacitor. 90003 90002 The meter used for this Wiki is the cheapest one available at any department store. For these test it is also advisable to use an analog multimeter. It will show the movement in a more visual way than a digital multimeter that only display rapidly changing numbers. This should enable anybody to perform these tests without spending a fortune on something like a Fluke meter. 90003 90002 Always discharge a capacitor before testing it, it will be a shocking surprise if this does not get done.Very small capacitors can be discharged by bridging both leads with a screw driver. A better way of doing it would be by discharging the capacitor through a load. In this case alligator cables and a resistor will accomplish this. Here is a great site showing how to construct a discharge tools. 90003 90002 To test the capacitor with a multimeter, set the meter to read in the high ohms range, somewhere above 10k and 1m ohms. Touch the meter leads to the corresponding leads on the capacitor, red to positive and black to negative.The meter should start at zero and then moving slowly toward infinity. This means that the capacitor is in working condition. If the meter stays at zero, the capacitor is not charging through the battery of the meter, meaning it is not working. 90003 90002 This will also work with SMD caps. Same test with the needle of the multimeter moving slowly in the same direction. 90003 90002 One more test that one can do on a capacitor is a voltage test. We know that capacitors store a potential difference of charges across their plate, those are voltages.A capacitor has an anode which has a positive voltage and a cathode which has a negative voltage. One way to check if a capacitor is working is to charge it up with a voltage and then read the voltage across the anode and cathode. For this it is necessary to charge the capacitor with voltage, and to apply a DC voltage to the capacitor leads. In this case polarity is very important. If this capacitor has a positive and negative lead, it is a polarized capacitors (electrolytic capacitors). Positive voltage will go to the anode, and negative goes to the cathode of the capacitor.Remember to check the markings on the capacitor to be tested. Then apply a voltage, which should be less than the voltage the capacitor is rated for, for a few seconds. In this example the 160V capacitor will be charged with a 9V DC battery for a few seconds. 90003 90002 After the charge is finished, disconnect the battery from the capacitor. Use the multimeter and read the voltage on the capacitor leads. The voltage should read near 9 volts. The voltage will discharge rapidly to 0V because the capacitor is discharging through the multimeter.If the capacitor will not retain that voltage, it is defective and should be replaced. 90003 90002 The easiest of course will be to check a capacitor with a capacitance meter. Here is a FRAKO axial GPF 1000μF 40V with a 5% tolerance. Checking this capacitor with a capacitance meter is straight forward. On these capacitors, the positive lead is marked. Attach the positive (red) lead from the meter to that and the negative (black) to the opposite. This capacitor shows 1038μF, clearly within its tolerance.90003 90002 To test an SMD capacitor may be difficult to do with the bulky probes. One can either solder needles to the end of those probes, or invest in some smart tweezers. The preferred way would be using smart tweezers. 90003 90002 Some capacitors do not require any test to determine failure. If a visual inspection of the capacitors reveal any sign of bulging tops, those need to be replaced. This is the most common failure in power supplies. When replacing a capacitor, it is of utmost importance to replace it with a capacitor of the same, or higher value.Never subsidize with a capacitor of lesser value. 90003 90002 If the capacitor that is going to be replaced or checked, does not have any markings on it, a schematic will be necessary. The image below from here shows a few symbols for capacitors that are used on a schematic. 90003 90002 This excerpt from an iPhone schematic indicates the symbol for capacitors as well as the values ​​for those capacitors. 90003 90002 This Wiki is pretty much just the basics about what to look for on a capacitor, it is in no way complete.To learn more about any of the common electronic components, there is a plethora of good on and offline course available. 90003 90002 Eaton Electronics 90003 90002 Maxwell 90003 90002 Digikey 90003 90002 Mouser 90003.90000 How To Test Electrical & Electronics Components with Multimeter? 90001 90002 90003 How To Test Electrical & Electronics Components with Multimeter? 90004 90005 90006 90003 Troubleshooting with Multimeter 90004 90009 90010 We all know the rule and importance of «Troubleshooting» in Electrical and Electronics Engineering. Most EE components and elements used in Electrical and Electronics equipments, devices and instruments are common in their functions and operations. 90011 90010 To be a good analyzer and troubleshooter, you must know the following basic techniques and has good skills in Electrical and Electronics troubleshooting, design and analyzing electric / electronic circuits.For this purpose, we have started a multimerer tutorial where we will use DMM (Digital Multimeter) and AVO Meter (Ampere-Voltage-Resistance Meter) or Multimeter (Digital / Analog) to test different electrical / electronics devices, instruments and components to find their terminals and condition such as are are they short, open, good or faulty. 90011 90010 In this basic multimeter tutorial, We will use digital and analog multimeter to check the following electrical and electronic components, devices, tools and instruments: 90015 90011 90017 90018 Cable and Wires 90019 90018 Switch / Push Buttons 90019 90018 Fuse 90019 90018 Capacitors & Inductors 90019 90018 Resistors & Burnt resistors 90015 90019 90018 Diodes and LED 90019 90018 Battery 90019 90018 Transistors 90019 90018 Relays 90019 90037 90010 90039 90039 90011 90010 In troubleshooting, we use different kinds of basic Electrical and Electronics Engineering Tools but the main and important tool is Multimeter.Now we will check the above mentioned components and devices with this tool one by one. 90011 90006 90003 Cable and Wires 90004 90009 90010 To check if the cable and wires are in good condition or broken before sizing the proper cable & wire for Electrical Wiring installation, we perform the continuity test. For this purpose, take AVO meter (or Digital Multimeter) and select «Resistance» (in AVO meter … Rotate the knob to the «Ω» or Resistance). 90011 90010 Now connect both terminals, i.e. both naked ends of the cable / wire with the AVO or Digital Multimeter Terminals. If the meter reading shown «0 Ω», it means Cable / Wire is in «Good Condition». On the other hand, if meter reading is «Infinite», it shows the cable / wire may be defected or broken. So you need to replace it with a new one. 90011 90006 90003 Switch / Push Buttons 90004 90009 90010 Use the same method (mentioned above for checking the cable and wires) … to perform this method correctly, you will need to apply this method in both cases (ON & OFF positions) on switches and push buttons … In other words, first apply this method on switches / push buttons and then «Push» the push button and perform the same method again.90011 90010 At first attempt, if meter reading is «Zero» and in the second attempt, the meter reading is infinite, it means Switch / Push button is in good condition. If Multimeter reading is «Zero» or «infinite» in both attempts, it means switch is in short circuit or continuity connection is broken and you should replace it with a new one. 90011 90006 90003 Fuse 90004 90009 90010 To verify Fuse condition, i.e. is «Fuse» in good condition or damaged? … We perform the same method I.e. continuity test as mentioned above.In short, if the meter reading is «Zero» it means Fuse is in good condition. If Multimeter reading is infinite, it means Fuse continuity may be broken or blown. So you should replace it with a new one immediately. 90011 90006 90067 90067 90003 Capacitor 90004 90009 90010 We have already discussed the topic «How to Check a Capacitor with Digital (Multimeter) and Analog (AVO Meter), By Four (6) Methods with pictorial views. 90011 90010 In this tutorial, you can check with Digital Multimeter or AVO meter if the Capacitor is Good, Short or Open? 90011 90006 90003 Diode & LED 90004 90009 90010 We have updated a detailed post about «How to Test a Diode using Digital & Analog Multimeter» by four methods.In this multimeter tutorial, we have shown different things about diode such as using diode mode in DMM and resistance mode in DMM and AMM to identify the terminals of Diode, LED and Zener diode. In addition, you may also check if the diode is good, bad, short or open. 90011 90006 90003 Transistor 90004 90009 90010 In another detailed multimeter tutorial about «How to Check a Transistor by Multimeter (DMM + AVO)» you may find the Base, Collector and Emitter of a transistor by using Digital and analog multimeter.Also, There is an easy method to remember the direction of NPN and PNP transistors. In short, in this tutorial, You will be able to use the multimeter in resisatnce mode (Digital + Analog multimeter) or hFE / Beta mode (Only DMM) to test a transistor if is it good, faulty, short or open. 90011 90006 90003 Battery 90004 90009 90010 In the basic test meter tutorial about «How to test a battery with Test meter?» you will be able to find if the battery is in good condition, charged, need to be charge, low charge / current, high charge / current or is it faulty and need to be replaced with new one.90011 90006 90003 Resistor & Burnt Resistors 90015 90004 90009 90010 To check if the Resistor is in good condition or broken, we use a multimeter. For this purpose, take AVO meter (or Digital Multimeter) and select «Resistance» (in AVO meter … Rotate the knob to the «Ω» or Resistance). Now connect both ends of resistor with the AVO or Digital Multimeter Terminals. If the meter reading shows the exact value of resistance or with a percentage tolerance, it means Resistor in «Good Condition».90011 90010 For Example, 1kΩ = 1000Ω with a 5% tolerance will show the reading near about 950Ω to 1050Ω. On the other hand, if meter reading is «Infinite», it shows the Resistor may be defected or broken and open. So you need to replace it with a new one (exact value). 90011 90010 Good to know: 90011 90010 You can also check the value of a burnt resistor with Digital or analog multimer by the following three handy methods. 90011 90010 Related Post: How to find The value of Burnt Resistor (By three handy Methods) 90011 90006 Relay Coils & SSR Relay 90009 90010 To test an SSR (Solid state relay) and electromechanical relay coils by using multimter, You will have to follow the detailed and step by step guide about «How to Test a Relay? Checking SSR & Coil Relays «90011 90006 90003 General Precaution 90004 90009 90017 90018 Disconnect the power source before checking, servicing, repairing or installing electrical equipments and devices.90019 90018 Always, Select the higher value in Digital or analog Multimeter, and then, gradually reduce it to the proper valve. 90019 90018 Never try to work on electricity without proper guidance and care 90019 90018 Read all instruction and cautions and follow them strictly. 90019 90018 The author will not be liable for any losses, injuries, or damages from the display or use of this information or try any circuit in the wrong format so please! Be careful because it’s all about electricity and electricity is too dangerous 90019 90037 90010 90130 Note: This basic multimeter tutorial has to be updated with new testing method with DMM + AMM … Stay tune.90131 90011 90010 Related Tutorials: 90011.90000 How to Use a Multimeter to Measure Voltage, Current and Resistance 90001 90002 What is a Multimeter? 90003 90004 A digital multimeter or DMM is a useful test instrument for measuring voltage, current and resistance, and some meters have a facility for testing transistors and capacitors. You can also use it for checking continuity of wires and fuses. If you like to DIY, do car maintenance or troubleshoot electronic or electrical equipment, a multimeter is a handy accessory to have in your home toolkit.90005 90004 90007 If you have any questions, just leave a comment at the end of this «how to» guide. Also if you find this article useful, please share a link to it on Facebook, Pinterest or other social media using the easy share buttons. 90008 90005 90004 90007 Thanks! 90008 90005 90002 Volts, Amps, Ohms — What Does it All Mean? 90003 90004 Before we learn how to use a multimeter, we need to become familiar with the quantities we are going to be measuring. The most basic circuit we will encounter is a voltage source, which could be connected to a load.The voltage source could be a battery or a mains power supply. The load might be an appliance such as a bulb or electronic component called a 90007 resistor. 90008 The circuit can be represented by a diagram called a 90007 schematic. 90008 In the circuit below, the voltage source V creates an electrical pressure which forces a current I to flow around the circuit and through the load R. Ohm’s Law tells us that if we divide the voltage V by the resistance R, measured in ohms, it gives us a value for the current I in amps: 90005 90022 90004 V / R = I 90005 90025 90002 Quantities and Terms Used in Electrical Engineering 90003 90028 90029 Volts 90030 90031 90004 This is the pressure between two points in an electrical circuit.It could be measured across the voltage source or other components connected in the circuit. 90005 90028 90029 Amps 90030 90031 90004 This is a measure of the current flowing between two points in an electrical circuit. 90005 90028 90029 Ohms 90030 90031 90004 A measure of the resistance to flow in a circuit. 90005 90028 90029 Voltage Source 90030 90031 90004 This produces a current flow in a circuit. It could be a battery, portable generator, mains supply to a home, alternator on your car engine or bench power supply in a lab or workshop.90005 90028 90029 Load 90030 90031 90004 90029 90030 A device or component which draws power from a voltage source. This could be an electronic resistor, bulb, electric heater, motor or any electrical appliance. A load has a resistance measured in ohms. 90005 90028 90029 Ground 90030 90031 90004 This is usually the point in a circuit to which the negative terminal of a battery or power supply is connected. 90005 90028 90029 DC 90030 90031 90004 Direct current. Current flows only one way from a DC source, an example of which is a battery.90005 90028 90029 AC 90030 90031 90004 Alternating Current. Current flows one way from a source, reverses, and then flows the other way. This happens many times a second at a rate determined by the 90007 frequency 90008 which is typically 50 or 60 hertz. The mains supply in a home is AC. 90005 90028 Polarity 90031 90004 A term used to describe the direction of flow of current in a circuit or which points are positive and which are negative wrt a reference point. 90005 90004 90029 For more detailed information about these quantities and terms, take a detour to my other article: 90030 90005 90004 Volts, Watts, Amps, Kilowatt Hours, What Does it All Mean? — The Basics of Electricity 90005 90002 What Does a Multimeter Measure? 90003 90004 A basic multimeter facilitates the measurement of the following quantities: 90005 90094 90095 DC voltage 90096 90095 DC current 90096 90095 AC voltage 90096 90095 AC current (not all basic meters have this function) 90096 90095 Resistance 90096 90095 Continuity — indicated by a buzzer or tone 90096 90107 90004 In addition meters may have the following functions: 90005 90094 90095 Capacitance measurement 90096 90095 Transistor HFE or DC current gain 90096 90095 Temperature measurement with an additional probe 90096 90095 Diode test 90096 90095 Frequency measurement 90096 90107 90004 The value measured by the instrument is indicated on an LCD display or scale.90005 90002 How Do I Setup a Multimeter to Measure Volts, Amps or Ohms? 90003 90004 Voltage, current and resistance ranges are usually set by turning a rotary range selection dial. This is set to the quantity being measured, e.g. AC volts, DC volts, Amps (current) or Ohms (resistance). 90005 90004 If the meter is non-autoranging, each function will have several ranges. So for example, the DC volts function range will have 1000V, 200V, 20V, 2V and 200mV ranges. Using the lowest range possible gives more significant figures in the reading.90005 90002 How to Measure Voltage 90003 90132 90095 Power off the circuity / wiring under test if there is a danger of shorting out closely spaced adjacent wires, terminals or other points which have differing voltages. 90096 90095 Plug the black ground probe lead into the COM socket on the meter (see photo below). 90096 90095 Plug the red positive probe lead into the socket marked V (usually also marked with the Greek letter «omega» Ω and possibly a diode symbol). 90096 90095 If the meter has has a manual range selection dial, turn this to select AC or DC volts and pick a range to give the required accuracy.So for instance measuring 12 volts on the 20 volt range will give more decimal places than on the 200 volt range. 90140 If the meter is autoranging, turn the dial to the ‘V’ setting with the symbol for AC or DC (see «What Do the Symbols on the Range Dial Mean?» Below). 90096 90095 A multimeter must be connected in parallel in a circuit (see diagram below) in order to measure voltage. So this means the two test probes should be connected in parallel with the voltage source, load or any other two points across which voltage needs to be measured.90096 90095 Touch the black probe against the first point of the circuitry / wiring. 90096 90095 Power up the equipment. 90096 90095 Touch the other red probe against the second point of test. Ensure you do not bridge the gap between the point being tested and adjacent wiring, terminals or tracks on a PCB. 90096 90095 Take the reading on the LCD display. 90096 90152 90004 90007 Note: A lead with a 4mm banana plug on one end and a crocodile clip on the other end is very handy. The croc clip can be connected to ground in the circuit, freeing up one of your hands.90008 90005 90002 Safety First When Measuring Mains Voltages! 90003 90132 90095 Before using a meter to measure mains voltages, ensure test leads are not damaged and that there are no exposed conductors which could be touched inadvertently. 90096 90095 Double check 90163 that test leads are plugged into the common and voltage sockets of the DMM (see photo below) and not the current sockets. This is essential to avoid blowing up the meter. 90096 90095 Set the range dial on the meter to AC volts and the highest voltage range.90096 90095 If you want to check the voltage at a socket outlet, switch off power using the switch on the socket. Then insert probes into the mains socket. If the socket outlet has no switch and you can not turn off power, insert a probe into the neutral pin first before inserting a probe into the hot (live) pin of the socket. If you insert the probe into the hot (live) pin first and the meter is faulty, current could flow through the meter to the neutral probe. If you then inadvertently touch the tip of the probe or the probe is left on a conductive metal surface, there is a possibility of shock.90096 90095 Probes with crocodile clips allow connections to be made with power turned off and do not have to be held in place when power is turned on. 90096 90095 Finally turn on the power switch and measure the voltage. 90007 90140 90008 90096 90152 90004 90029 Ideally buy and use a meter with a least CAT III or preferably CAT IV protection for testing mains voltages. This type of meter will incorporate high rupturing capacity (HRC) fuses and other internal safety components that offer the highest level of protection against overloads and transients on the line being tested.A meter with less protection can potentially blow up causing injury if it is connected incorrectly, or a transient voltage generates an internal arc. 90030 90005 90004 If you are measuring voltage at a consumer unit / breaker box / fuse box, this video from Fluke Corporation outlines the precautions you should take 90005 90004 Safe Practice When Taking Single Phase Measurement 90005 90004 Also these safety guidelines by Fluke explain the hazards of voltage spikes and the Overvoltage Installation Category 90005 90004 ABCs of Multimeter Safety 90005 90002 Autoranging Meters 90003 90004 Autoranging meters detect the magnitude of the voltage and select the range automatically to give the most amount of significant digits on the display.You must however set the mode to resistance, volts or current and also connect the probe leads to the proper sockets when measuring current. 90005 90002 Identifying Live or Hot Wires 90003 90004 A Fluke «VoltAlert ™» non-contact voltage detector is a standard tool in any electricians tool kit, but useful for homeowners also. I use one of these for identifying which conductor is live whenever I’m doing any home maintenance. Unlike a neon screwdriver tester (phase tester), you can use one of these in situations when live parts / wires are shrouded or covered with insulation and you can not make contact with wires.It also comes in useful for checking whether there’s a break in a power flex and where the break occurs. 90005 90004 Note: It’s always a good idea to use a neon tester to double check that power is definitely off when doing any electrical maintenance. 90005 90002 What Multimeter Should I Buy? 90003 90004 When asked, Fluke, who are a leading US manufacturer of digital instrumentation, recommended the Fluke 113 model for general purpose use in the home or for car maintenance. This is an excellent meter and can measure AC and DC volts, resistance, check continuity and diodes.The meter is auto-ranging, so ranges do not have to be set. It is also a true-RMS meter. It does not measure current, so If you need to measure AC and DC current, the Fluke 115 has this added facility. 90005 90004 An alternative is the Fluke 177 model which is a high accuracy instrument (the specification is 0.09% accuracy on DC volts). I use this model for more accurate testing and professional use and it can measure AC and DC voltage and current, resistance, frequency, capacitance, continuity and diode test.It can also indicate max and min values ​​on each range. 90005 90002 Measuring Large Currents with a Clamp Meter (Tong Tester) 90003 90004 On most multimeters, the highest current range is 10 or 20 amps. It would be impractical to feed very high currents through a meter because normal 4 mm sockets and test leads would not be capable of carrying high currents without overheating. Instead, clamp meters are used for these measurements. 90005 90004 Clamp meters (as the name suggests), also known as tong testers, have a spring loaded clamp like a giant clothes peg which clamps around a current carrying cable.The advantage of this is that a circuit does not have to broken to insert a meter in series, and power need not be turned off as is the case when measuring current on a standard DMM. Clamp meters use either an integrated current transformer or hall effect sensor to measure the magnetic field produced by a flowing current. The meter can be a self contained instrument with an LCD which displays current, or alternatively the device can output a voltage signal via probe leads and 4mm «banana» plugs to a standard DMM.The voltage is proportional to the measured signal, typically 1mv represents 1 amp. 90140 Clamp meters can measure hundreds or thousands of amps. 90140 To use a current clamp, you simply clamp over a single cable. In the case of a power cord or multicore cable, you need to isolate one of the cores. If two cores carrying the same current but in opposite directions are enclosed within the jaws (which would be the situation if you clamp over a power cord), the magnetic fields due to the current flow would cancel out and the reading would be zero.90005 90002 How to Check Continuity and Fuses 90003 90004 A multimeter is useful for checking breaks in flexes of appliances, blown filaments in bulbs and blown fuses, and tracing paths / tracks on PCBs 90005 90132 90095 Turn the selecting dial on the meter to the continuity range. This is often indicated by a symbol which looks like a series of arcs of a circle (90007 See the photo showing symbols used on meters above). 90008 90096 90095 Connect the probe leads to the meter as shown in the photo below.90096 90095 If a conductor on a circuit board / a wire in an appliance needs to be checked, make sure the device is powered down. 90096 90095 Place the tip of a probe at each end of the conductor or fuse which needs to be checked. 90096 90095 If resistance is less than about 30 ohms, the meter will indicate this by by a beep tone or buzzing sound. The resistance is usually indicated on the display also. If there is break in continuity in the device being tested, an overload indication, usually the digit «1», will be displayed on the meter.90096 90152 90002 How to Check Diodes 90003 90004 A multimeter can be used to check whether a diode is short circuited or open circuited. A diode is an electronic one way valve or 90007 check valve 90008, which only conducts in one direction. A multimeter when connected to a working diode indicates the voltage across the component. 90005 90132 90095 Turn the dial of the meter to the diode test setting, which is indicated by a triangle with a bar at the end (90007 see the photo showing symbols used on meters above).90008 90096 90095 Connect the probes as shown above. 90096 90095 Touch the tip of the negative probe to one end of the diode, and the tip of the positive probe to the other end. 90096 90095 When the black probe is in contact with the cathode of the diode (usually indicated by a bar marked on the component) and the red probe makes contact with the anode, the diode conducts, and the meter indicates the voltage. This should be about 0.6 volts for a silicon diode and about 0.2 volts for a Schottky diode.When the probes are reversed, the meter should indicate a «1» because the diode is open circuit and non-conducting. 90096 90095 If the meter reads «1» when the probes are placed either way, the diode is likely to be faulty and open circuit. If the meter indicates a value close to zero, the diode is shorted circuited. 90096 90095 If a component is in circuit, resistances in parallel will affect the reading and the meter may not indicate «1» but a value somewhat less. 90096 90152 90002 How to Measure Wattage and the Power Consumption of an Appliance With a Multimeter 90003 90002 Watts = Volts x Current 90003 90004 90029 90140 90030 So to measure the power in watts of a load / appliance, both the voltage across the load and the current passing through it must be measured.If you have two DMMs, you can measure the voltage and current simultaneously. Alternatively measure the voltage first, and then disconnect the load so that the DMM can be inserted in series to measure current. When any quantity is measured, the measuring device has an influence on the measurement. So the resistance of the meter will reduce current slightly, and give a lower reading than the actual value with the meter not connected. 90005 90004 The safest way to measure the power consumption of an appliance powered from the mains is to use a power adapter.These devices plug into a socket and the appliance is then plugged into the adapter which displays information on an LCD. Typical parameters displayed are voltage, current, power, kwh, cost and how long the appliance was turned on (useful for fridges, freezers and air conditioners which cut in and out). You can read more about these gadget in my article here: 90005 90004 Checking Power Consumption of Appliances With an Energy Monitoring Adapter 90005 90004 An alternative way of safely measuring current drawn by an electrical appliance is to make up a test lead using a short piece of power cord with a trailing socket on one end and a mains plug on the other.The inner neutral core of the power cord could be freed and separated from the outer sheath, and current measured with a clamp meter or probe (Do not remove the insulation!). Another way is to cut the neutral core, add 4mm banana plugs to each of the cut ends and plug these into the meter. 90029 90268 Only make connections and adjust range on the meter with the power off! 90269 90030 90005 90002 How to Check Peak Voltages — Using a DVA Adapter 90003 90004 Some meters have a button which sets the meter to read max and min RMS voltages and / or peak voltages (of the waveform).An alternative is to use a DVA or Direct Voltage Adapter. Some components such as CDI (Capacitor Discharge Ignition) modules on vehicles, boats and small engines produce pulses which vary in frequency and can be short duration. A DVA adapter will sample and hold the peak value of the waveform and output it as a DC voltage so the component can be checked to see whether it’s producing the correct voltage level. A DVA adapter typically has two probe leads as input for measuring voltage and either two output leads with banana plugs or a connector with fixed plugs attached for plugging into a meter with standard spaced sockets.The meter is set to a high DC voltage range (e.g. 1000 volts DC) and the adapter typically outputs 1 volt DC per 1 volt AC input. 90005 90004 90029 Important information for anyone using a DVA to check ignition circuits! 90030 90005 90004 In this application, the adapter is used for measuring the primary voltage of a stator / ignition coil, not the secondary voltage, which could be about 10,000 volts or more. 90005 90004 Fluke also manufacture meters that can capture the peak level of short transients e.g. — The Fluke-87-5, Fluke-287 and Fluke-289 models. 90005 90002 True RMS Multimeters 90003 90004 The voltage supply to your home is AC, and voltage and current vary in polarity over time. The waveform is sinusoidal as in the diagram below and the change of direction of current is known as the frequency and measured in Hertz (Hz). This frequency can be 50 or 60 Hz, depending on which country you live in. The RMS voltage of an AC waveform is the effective voltage and similar to the average voltage.If the peak voltage is V 90287 peak 90288, then the RMS voltage for a sinusoidal voltage is V 90287 peak 90288 / √2 (approx 0.707 times the peak voltage). The power in a circuit is the RMS voltage multiplied by the RMS current flowing in a load. The voltage normally printed on appliances is the RMS voltage even though this is not usually stated. 90140 A basic multimeter will indicate RMS voltages for sinusoidal voltage waveforms. The supply to our homes is sinusoidal so this is not a problem. However if a voltage is non sinusoidal, e.g. a square or triangular wave, then the meter will not indicate the true RMS voltage. True RMS meters however are designed to correctly indicate RMS values ​​for all shaped waveforms. 90005 90002 Measuring Voltages Remotely and Logging Readings 90003 90004 If you need to measure voltages and log them over time, you can use a datalogging multimeter. A product such as the Fluke 289 True-RMS datalogging multimeter can record 15,000 readings. Another feature of this meter is that it can be setup with a wireless connector to communicate with an Android mobile device, allowing readings to be viewed remotely, while the meter is located elsewhere.90005 90002 FAQs About Multimeters 90003 90028 How Do You Check Voltage With a Multimeter? 90031 90004 Plug the black probe into COM and the red probe into the socket marked VΩ. Set the range to DC or AC volts and touch the probe tips to the two points between which voltage needs to be measured. 90005 90028 How Do You Check if a Wire is Live With a Multimeter? 90031 90004 For this it’s best to stay safe and use a non-contact volt tester or phase tester screwdriver. These will indicate if voltage is e.g> 100 volts. A multimeter can only measure the voltage between live and neutral or live and earth if these conductors / terminals are accessible, which may not always be the case. 90005 90028 How Do You Check Voltage Drop With a Multimeter? 90031 90004 Voltage drop occurs across a resistance or along a power cable. So follow the same procedure as for measuring voltage and measure voltage at the two points of interset and subtract one form the other to measure voltage drop. 90005 90028 Why is Voltage Drop Important? 90031 90004 If voltage drop is excessive, appliances may not work properly.Cable should be sized adequately to minimise voltage drop for the current it needs to carry and the distance over which current travels. 90005 .