Note: the solenoid text in the image is just a representation.

Real world everything is fine until I connect the solenoid to the Com and N/O of the relay. It then cycles once and starts to continuously re-trigger on it's own once a second or so. I disconnect the solenoid and it works as it should.

I have used the common 12V as in the image and I have also given the solenoid it's own separate 12V but it makes no difference.

enter image description here

  • \$\begingroup\$ everything is fine until I connect the solenoid to the Com and N/O of the relay - that would be an incorrect connection and one that just plainly wouldn't work and do nothing. Unless of course you mean the NC connection as per your (ahem) schematic. \$\endgroup\$ – Andy aka Apr 4 at 14:41
  • \$\begingroup\$ @Andyaka Actually, that appears to be the NO connection, given that the output of the 555 is currently high. \$\endgroup\$ – Hearth Apr 4 at 14:45
  • \$\begingroup\$ Then what has been posted is not a schematic diagram then. \$\endgroup\$ – Andy aka Apr 4 at 14:46
  • \$\begingroup\$ Hearth you are correct. That is the output of a simulation currently high on the output. Any ideas as to why it fails when the solenoid is in the cct and running. Real world breadboard failure not simulation. \$\endgroup\$ – Joe444 Apr 4 at 15:24
  • \$\begingroup\$ What has the supply got in it, that's not shown. Any supply decoupling you've missed off? \$\endgroup\$ – TonyM Apr 4 at 15:34

I think I found the problem, and as always the answer is in the question. The solenoid when in the circuit causes the problem.

I had the 555 trigger wire from a sensor alongside the solenoid wires and no shielding. Solenoid de-energizes sending RF interference to the trigger. Never ending loop.

Thanks for the help.


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