How to use relay and Arduino on one Samsung charger


I have old Samsung charger. I want to make something with Arduino and relay. They are both using one charger. Problem is that when I turn on relay, (with transistor, no overload on microcontroller) power is very low in microcontroler and sometimes I had problem that relay went crazy and was ticking unlimited times coz there was not enough voltage for arduino...

So, I want to set "limiter" on relay. it is 3 volt relay and I don't want for it 5 volts. Is there any way to solve this problem? To use both Arduino and relay on one 5V charger ?


Of course there is, use some bad ass charger, capable of charging with something like 2 Ampere.
Or use a bad ass capacitor that will be able to supply the relay while it is switching on.
Or use a big capacitor to the Arduino power supply.
Or all of the above.

it is 3 volt relay and I don’t want for it 5 volts.

Measure the resistance of the relay coil.
Use a resistor that is <= 2/3 of that value, and connect it in series with the coil.
Maybe the resistance is written on the relay, or you have the datasheet.


Will try both solutions.


Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

It will be worth a thousand words just to see if you have got the gnds connected.

Tom.... :slight_smile: