Filter Capacitor for relay

Thread Starter

Dakk33

Joined Jun 19, 2019
4
Hello all,

So I've made a circuit that actuates a solenoid using a relay. The relay is getting a 5V signal from a microcontroller. I've been advised to add some capacitors to filter out any noise for the signal on the relay. Does anyone have any input on what I should be looking for in terms of capacitance and how I should add the capacitor in the circuit (in series with the signal, or in parallel across the relay?)

Attached is a drawing of the circuit.
 

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AlbertHall

Joined Jun 4, 2014
8,778
You have the diode to catch the back EMF from the solenoid so I don't think it needs anything added. The solenoid is on a different supply to the microcontroller so they shouldn't interfere with each other.
 

Thread Starter

Dakk33

Joined Jun 19, 2019
4
You could use a BEMF diode across the relay coil also maybe.
Had you considered a logic level Mosfet in place of a relay?
Max.
I've been considering adding a flyback diode on that side of the relay. Do you have any resources or recommendations for a MOSFET instead of the relay?
 
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