• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

relay contact chattering

Not open for further replies.


New Member
Hi. New to the forum here.

what Im doing is simple. Im hooking a small 12vdc .3 amp flow pump to a relay controlled by a switch. The relay is a yong lin YL-314-c-12VDC single pole double throw and the coil draws .13 amps. I tested the relays hooked up to the pump with my RSR electronics inc 3040 power supply and the relay will not engage the contact and it just chatters when I throw the switch to the coil. Now when I physically press the contact down it engages and stops chattering.

The rating for the power supply is 1amp at 12 volts. At maximum the relay and pump are only drawing .43 amps. What I want to know is should I put a damper capacitor in there, Where should I put it and what kind do I need. Also consider that this relay and pump will be going into my truck and will be supplied by a much heavier capacity circuit (which I haven't tested yet).

Is this a problem with the motor suddenly drawing alot of current and draining power for the relay coil and causing it to chatter. Or am I missing something.

I haven't dealt with anything electronics related in over 10 years. I have experience but I a little rusty.
Last edited:


New Member
You may need a low resistance voltage source and a single point ground for both the relay and the pump to keep the relay from oscillating.


Well-Known Member
Most Helpful Member
Can you post a schematic of how you are connecting the relay and motor to the power supply?


That's a big cap colin. You can't just throw that in a circuit and expect normal behavior, the start up current of that if the power supply has a 1 ohm series resistance will be over 20 amps. Could damage part of the power circuit, or simply cause the power supply to go into foldback mode every time it starts up.
Last edited:
Not open for further replies.

Latest threads

EE World Online Articles