Relay switching and the PSU

[Bernardduur]

Hey all!

I wanted to add a relay switcher to turn my tremolo on and off; right now I find it annoying that I can't see if my tremolo is on or off. And with such a wiring I could use my old (t)rusty amp switcher that I use for my other amps.

I'm trying to understand it here; my amp has a 6.3V 4.5A line that has a middle grounding. When I add a normal rect I get around 3V on the lines which is normal but too little for a 6V relay

So I tried building a voltage doubler with this stage but when I fire her up the bottom diode melts up in smoke........ my main parts-guy told me it was due to the 4.5A of this line. Should I enlarge the diodes to the 6A specs and try again or am I overlooking something? I wanted to use a 7806 voltage regulator but due to this higher current is that maybe not adviseable?

[gmoon]

Your parts-guy is giving you a bum-steer. There's some other wiring issue here--a relay alone won't draw enough current to fry the diode. There's some other current path.

Check the doubler, and if the CT isn't already grounded, check if the 6.3V coil is separate from the other secondary coils...

[Bernardduur]

Hmmm, yes, I thought so too. Right now there is no relay attached to the power just the voltage doubler (consisting of 2 diodes and 2 1000 uF caps) + a filter cap. It is always the same diode that burns down (the one with the kathode to the AC and the anode to the ground)

The CT of the 6.3 is grounded

[pdf64]

If the CT is grounded then you can't connect the + or - output from the voltage doubler to ground also. If you are using grounded jack / RCA sockets to connect the footswitch, then there is the problem. Peter.

[Steve Conner]

Correct. Grounding one side of the doubler's output will short it and burn the diodes.

I have a circuit I posted on the forum a while back, that generates a +12V rail referenced to ground from a 6.3V heater winding center tapped to ground.

[Bernardduur]

Ah yes, that makes a lot of sense........

I simulated the voltage doubler + grounded CT and that one gave no problems...... guess the simulation software isn't that great

Steve, thanks for the clue; I found the schematic and got great results!

[Steve Conner]

Simulated components don't have any magic smoke to come out when they're unhappy

BTW, where did you find the schematic, I can't remember where I posted it, and had no luck searching for it either!

[Bernardduur]

Haha, usually the software calls when a component fails.......... a well........

Here is the schematic I searched for it long and found it by combining "center" and "Steve Conner" as a bit of a wild guess...........