Why is my relay switching Buzzing!

[kurtlives]

Just finished a tube preamp now I am working on the switching for it. Keeping it very simple for now... No LED indicator no anti popping circuit.

Basically the set up is true bypass using a standard DPDT (non-latching relay). When the coil is not energized it's in bypassed mode, energize the coil and the pre-amp is in the signal path.

The coils path to ground is broken by a SPST switch. A pic will help....



Now it works in both bypassed and effect mode but there is a loud constant hum. Cant figure out what is causing it? Help?

Thanks...

EDIT: Forgot to mention that when I touch the SPST switch in the enclosure the hum goes away.

[kurtlives]

Could the hum come from the excess wires on my breadboard where this little experiment is taking place?

[grapefruit]

What is the sleeve of the jack socket near the relay connected to?

Stew.

[kurtlives]

It is connected to the - of my breadboard.

It is actually a non isolated jack, unlike what I put on the pic.

[grapefruit]

Could be a number of things really. The breadboard wouldn't be helping.
Is it buzz or hum, or both?
Did you have this problem before you put the relay switching in?
Do you have a cro to check for ripple on the power supply?

Stew.

[Andi]

EDIT: Forgot to mention that when I touch the SPST switch in the enclosure the hum goes away.

That immediately makes me think that things aren't properly shielded.

[kurtlives]

Ya me too, but I cant figure out where?


It is a constant buzz/hum.

Did not have this problem before. Before I just hardwired the INs and OUTs right to the jacks of the unit.

[grapefruit]

I'd check earth continuity from your power/signal ground to the metal enclosure and switch.
If that's ok you could try disconnecting the wires from the relay coil and energising it from a separate battery. At least that will head you in the direction of what's causing it.

Stew.