# How to measure voltage with a multimeter?

September 30, 2018 at 05:47:05
Specs: several
 I have an appliance that has an electrical connector topower a subsidiary device that includes a motor. I don'thave that device and don't want it. Instead, I want to usepower from the connector to power a small lamp. I don'thave the specs for either the appliance or the subsidiarydevice. I don't know the voltage supplied by the connector.I don't even know if it is AC or DC. The connector looksvaguely like a Molex connector, with compartments for 8contacts, but it looks like only 4 of the compartments havecontacts in them, in an alternating pattern. How do I use a multimeter to determine the voltage andwhether it is AC or DC? How do I determine if one of theconnectors is to ground? -- Jeff, in Minneapolis message edited by Jeff Root

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#1
September 30, 2018 at 06:01:22
 Why so vague? You post on here often enough; you should know what's required. Why not mention what the appliance is & the make/model? We have no idea what you're working with. We also know nothing about the lamp. Did you try searching for the specs or electrical diagram for this "appliance"?

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#2
September 30, 2018 at 06:19:59
 I take it you know how to use your multimeter to measure voltage. (If not, read the instructions that came with it - it's nt possible to safely give generic instructions as all instruments are different.) So your main problem is to determine whether it is AC or DC. Have a look at this thread: https://www.edaboard.com/showthread...

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#3
September 30, 2018 at 08:21:27
 I should have said that my multimeter is analog and fairly basic. There isn't any need to know what the appliance is to answer thequestion. It is a general question calling for a general answer thatwill apply to a wide range of situations. I ask the question because all instructions for measuring voltage(including the instructions for my multimeter) say to measureacross a load. Across an existing circuit. I don't have a circuit.I don't have any idea what the load would be from the device thatplugs into the connector. I just want to measure how much juicecomes from the power supply, which is hidden inside the appliancewhere I can't examine it directly. All I know is that it is enough topower a small motor. And that it must be lowish voltage since itisn't a standard 120 volt AC outlet. Also there are four conductors, so I wonder what they all are.The third could be ground, but what is the fourth? -- Jeff, in Minneapolis

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#4
September 30, 2018 at 08:32:44
 "There isn't any need to know what the appliance is to answer thequestion. It is a general question calling for a general answer thatwill apply to a wide range of situations."OK, if that's the way you want to play it...I'm going to assume it's a dishwasher. Maybe this will help: https://www.doityourself.com/forum/...

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#5
September 30, 2018 at 15:20:47
 "Turbidity sensor", eh? Interesting. I wonder how that works. One thing I notice is that only two wires come in: A black wire attop-left labeled "L1" (If I read the fuzzy JPG correctly) and a whitewire at bottom-left labeled "N". Maybe for "neutral". No ground. Another thing I notice is that I don't see any voltage-reducingcomponents. No transformers or resistors. Nor do I see anyindication of voltages anywhere. Since one of the connectorsin the "sensor" connector block is labeled "LED", I know theremust be some reduction from 120 volts AC to low-voltage DC. It isn't clear that this helps answer my question, though it ismoderately interesting. If I want to find out what kind of voltage my wall outlets provide,do I just set my multimeter to 250 V AC and thrust the probesinto the socket? Or does that let the smoke out of my meter? -- Jeff, in Minneapolis

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#6
October 3, 2018 at 05:44:58
 No EEs here? -- Jeff, in Minneapolis

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