Relay power supply and wiring. Will it work?

[Bob-I]

Bob, I'm not sure but somewhere (here or maybe the GearPage) I read that some folks didn't like having the relays on the mains transformer. I use a separate transformer.

On my 4 current amps I have 4 different relay supplies.

1) Weber switch board. easy to install but the DIY in me wanted to do it myself.

2) Unregulated 6V supply off the heater windings.

3) Regulated 5V supply off the unused 5VAC tap

4) 12V regulated using a seperate 12VAC xformer. This one started by using the bias supply line but I had terrible noise issues, hum and diode noise both.


The resistor on the red LED is 48 ohms and the one on the green is 120 ohms. It is just enough resistance to light the LED but it has an independent signal to ground so the relay trips. In the case of the amp I'm finishing, the 12v line is also the indicator light supply for the D-lator switch so it needs to be available without a relay.

BTW, until tonight, I used a DPDT stomp switch for the OD. It is in a two switch Hammond box. The boost is just SPST. The OD switch has the feed for the OD and another for the boost in parallel with the stand-alone boost switch. I built the HRM first. Since both tone stacks muddy the sound, I rigged it so hitting the OD would turn them both on but the boost could be used independently. I'm using the same stomp box for the Hybrid now so I went back to the usual method. I've got wide feet so I can get them both with one step.

Great idea. I was thinking that there's no reason that we can't install the HRM controls on the panel. Why not have some tone adjustment with OD/PAB.

[Tdale]

OK. But there is nothing wrong with using the 5V secondaries on my PT...except from the thing about not using the same transformer for relays and the rest of the amp.

I stopped by my local tv-repair man, and he ok'ed your circuit for 5V secondaries use.

Tommy

['67_Plexi]

After many different trials of relay circuits, I found the winner was to do it just like Dumble did....how strange !!

Radioshack 6.3-0-6.3 transformer, use one secondary into a rectifier/voltage doubler circuit (two 1000uF caps, two diodes) and regulate it using a 7812 along with another 1000uF cap. Keep the ground floating (very important).
Use an isolated xlr socket. Send 12 V driectly to the relay coils and switch the floating ground. I also copied the original and sent a seperate 12V supply (through a current limiting resistor) to feed the footwitch LED.
I use Samsung 12V miniature relays. This gives silent operation even with a dual master HRM.

[Tdale]

a floating ground means not grounding to chassis, but just connecting all the leads that would normally be grounded, and wire them to the negative side of the power supply?

Tommy

['67_Plexi]

correct.

[Tdale]

No danger of getting electricuted while holding the guitar?

Tommy

['67_Plexi]

Huh ? I think you are getting something else mixed up here.
It's the 12V thats isolated from ground.

All you are doing is making the negative return path back to the 12V psu something other than the chassis. It helps eliminate switching pops. There's no safety ground involved, it's just a piddly 12V supply.
There will be no potential difference (voltage) between the chassis and any of the footswitch connections anyway.