RELAY POWER SUPPLY

[ViperDoc]

Please excuse my assumptions, I'm really just trying my best to get it. I never heard the term "normal" in circuitry until I studied patch bays, which as you know are "normalized" to a certain default routing by design. Since the relay spec sheets used the terms "normally open", etc., I thought that might be common terminology, and you helped clarify WHAT THAT ACTUALLY MEANT in your kind response regarding the energizing. NOW THAT TOTALLY MAKES SENSE.

The foot switch battery option sounds quite simple, I think I'll follow your recommendation on that. It makes the cliff stereo jack option possible. I'll leave the 5-pin for when my head won't explode.

Thanks again for your help!

[SoulFetish]

With a 9V supply, make sure you increase that LED limiting resistor to 3.3-3.9k. A standard red LED should have plenty of brightness at no more than 2mA or so.

[sluckey]

With a 9V supply, make sure you increase that LED limiting resistor to 3.3-3.9k. A standard red LED should have plenty of brightness at no more than 2mA or so.

Good idea.

[ViperDoc]

Just taking another look at relay power with respect to using the tube heaters instead of a separate transformer with respect to the 5V power supply ground.

If I'm using a PT that has a grounded 6.3 VAC heater center tap, and I'm using a Hoffman relay supply board like this:



...would I simply not ground the 5V power supply's bridge rectifier? Or would I need to rewire the diodes like this?

[REMOVED FOR CORRECTION]
Thanks as always.

[sluckey]

If I'm using a PT that has a grounded 6.3 VAC heater center tap, and I'm using a Hoffman relay supply board like this:
...would I simply not ground the 5V power supply's bridge rectifier?

Nothing on that board can be connected to ground. IOW, the 5v and grnd must float.

Or would I need to rewire the diodes like this?
RELAY RECTIFIER WIRING.pdf

Neither A nor B are correct.

[ViperDoc]

Ah, I appreciate the fine detail QC. Is this correct?

pt relay supply 2.pdf

[sluckey]

Yes. Just remember that the negative output lead can never touch chassis ground. It must float. This includes any footswitch jacks.

[ViperDoc]

Yes. Just remember that the negative output lead can never touch chassis ground. It must float. This includes any footswitch jacks.

Great, thank you!

[martin manning]

Ah, I appreciate the fine detail QC. Is this correct?
pt relay supply 2.pdf

I don't know why you couldn't ground the bridge and the 5V supply to the chassis (CT not used), and let that be the ground reference for the heater circuit. It'd be easy enough to try and see if there is any difference in noise level.

[ViperDoc]

Ah, I appreciate the fine detail QC. Is this correct?
pt relay supply 2.pdf

I don't know why you couldn't ground the bridge and the 5V supply to the chassis (CT not used), and let that be the ground reference for the heater circuit. It'd be easy enough to try and see if there is any difference in noise level.

Other than observed noise differences, would the ground reference through the bridge rectifier be equivalent to the heater CT wrt to the heaters?

[martin manning]

Other than observed noise differences, would the ground reference through the bridge rectifier be equivalent to the heater CT wrt to the heaters?

The heater voltage will be centered around zero, so basically equivalent, yes.