Electronic – Increase voltage and current with external power supply

amplifiercurrentpower supplyvoltage

I have an ECU A controlling a relay, in which when there is an activation command I can measure 12 V and 100 mA.

The project I'm working on is to replace that ECU A with an ECU B, but when I send my activation command to the relay, it is only able to draw 12 mA from ECU B due to internal limitations. The voltage I measure in that situation is 3 V, but ECU B has a voltage driving system connected to a 12 V supply.

My question is what kind of circuitry I can use to increase both the voltage and the current to reach the values I got with ECU A. I have access to a power supply of 12 V, which is the one being used for the voltage driving system. I imagine some sort of amplifier would be the necessary component, but then which type and how to determine the specs for it?

My background on electrical circuits is not very extensive, so please bear with me. I could really use your feedback. Thank you!

Best Answer

It sounds to me that with a limited ability to drive current to the relay you are currently using you have two options: -

  1. Choose a relay that takes less current (maybe an opto relay or SSR)
  2. Use a MOSFET (that can be driven from the IO line at low current) to connect the relay coil to 12 volts. Don't forget the flyback diode of course.

The 2nd option would require an N channel MOSFET interface like this: -

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