LM358: Relay chatter issue

Hi Murthy,

I would add a 100n cap from the wiper of 50k pot to signal ground and a hysteresis resistor from the +input of LM358 to its output. I would increase the 2k base resistor and add a 100n cap from the base to signal ground.

What is the relay winding resistance?

Does the relay already contain a free wheeling diode? If not, add such a diode with the anode connected to the collector and the cathode to +24V. Mount it close to the relay.

Then, a 100n supply voltage decoupling cap should be mounted close to the LM358 and a filtering cap could be mounted across the lower resistor of input voltage divider (10k). Even the relay will profit from a 100n decoupling cap.

And finally, there could be an issue with the signal ground routing. Provide a star ground routing with the ground star located at the ground pin of LM358.

Kai

Yes, Sir, I will do the changes.

External Freewheeling diode used. Relay winding resistance: 500 Ohms.

Hi Murthy,

in this case you can increase the base resistor to 5k1.

Kai