I have small knowledge about electronics in general, my question is how to measure the current used by switching operation on relay ? where should I put my (+) probe and (-) probe ? Correct me if I'm wrong, I break the 5V to VCC connection then, I connect my (+) probe to the 5V of arduino then, …

For those relays, the typical logic signal current is 2 ~ 4mA, the coil activation current about 72 ~ 75mA (including the transistor base current, 2 ~ 3mA). [OptoRelayChannelData-575]

Please post a link to the relay module, a wiring diagram and state which Arduino your are using. The 5V output of most Arduinos cannot supply much current. You should avoid drawing more than about 100 mA from it, depending on how the Arduino is powered. Check the specifications of the relay module…

So in general, it's not safe to powering the relay directly from 5v of arduino ? Should I use external power supply instead ?

don't have the datasheet, but my relay is exactly this one : https://components101.com/switches/5v-single-channel-relay-module-pinout-features-applications-working-datasheet

Thanks for posting the link to the product page. These are the important data as far as the Arduino is concerned. It is OK to power one of these modules from the 5V output. Supply voltage – 3.75V to 6V Quiescent current: 2mA Current when the relay is active: ~70mA

but isn't it exceed the current limitation of arduino pin which is 40 mA ? in that explanation it was +- 70 mA

The 70 mA is the current drawn by the relay coil from the 5V power source Vcc. The current drawn from the port pin by the "Input" terminal is limited to about 4 mA by the series 1K base resistor in the schematic below, so that is safe too. [image]

Ahhh... I see... so the 40mA limit is for the I/O pins right? question : so If I want to measure the current signal, I should break the connection between arduino pin - IN pin of relay, and then connect my (+) probe to the arduino pin, connect my (-) pin to the IN pin. Is this the right way to do …

[image] raejinn96: I should break the connection between arduino pin - IN pin of relay, and then connect my (+) probe to the arduino pin, connect my (-) pin to the IN pin. Is this the right way to do it ? To measure current with a meter, you have to break the connection. The meter adds some …

Do you want to measure the current needed to switch the relay? Or the current going via the switch of your relay? Measuring a current means always: break the wire put an AmpMeter in series into the broken wire (to close it again, now via the AmpMeter) set a Multi-device to Amp mode (not voltage …

Measuring current used by Relay Module switching operation

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jremington February 2, 2023, 1:46am 4

Some relays may not be powered from the 5V output. Yours may be fine.

Post a link to the data sheet for your relay.

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Measuring current used by Relay Module switching operation

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