Author Topic: Voltage regulator in Valvecaster  (Read 2326 times)

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Voltage regulator in Valvecaster
« on: December 06, 2009, 05:18:21 PM »
I've built a Valvecaster for someone but now they've asked if I can make it run off 18v. If I throw a LM7812 voltage reg in there, is it likely to introduce noise into the circuit? Or would I be better off just getting a large ceramic resistor (of appropriate value) to drag the voltage down?

petemoore

Re: Voltage regulator in Valvecaster
« Reply #1 on: December 06, 2009, 06:12:36 PM »
I've built a Valvecaster for someone but now they've asked if I can make it run off 18v.
  What voltage is it running at now ?
  If I throw a LM7812 voltage reg in there, is it likely to introduce noise into the circuit?
  No, but you may want to use the suggested output filter component[s.
  Or would I be better off just getting a large ceramic resistor (of appropriate value) to drag the voltage down?
  If you're dropping from 18v to 12v using a 7812, it might get warm/hot, I've never made that V-drop/current with one though, I'm sure others have. the V-reg has the advantage of providing a smooth regulated voltage. Another option would be a zener diode.
  The V-reg is pretty easy to work with, make sure the chip drawing has the pins labeled right under it, even if you have to de-code and redraw it off the data sheet. 
Convention creates following, following creates convention.

Re: Voltage regulator in Valvecaster
« Reply #2 on: December 06, 2009, 06:38:36 PM »
I'm well familiar with the use of 78* series regulators, just wasn't sure if it would introduce noise. I'm running it off 12v at the moment but this guy is wondering about running it off 18v as it would make his life easier (apparently  ???). A 7812 just seems the easiest option as I can heatsink glue it to the aluminium enclosure, right near the dc jack

petemoore

Re: Voltage regulator in Valvecaster
« Reply #3 on: December 07, 2009, 05:54:57 AM »
  What is or would be behind the regulators, a wall wart ?
  The reg's need ~2vdc 'extra' to work with, pick your output voltage [say 7818, and add at least 2volts to that for it's input voltage.
  For 18vdc supply, >20v, say 22v [a little extra elbow room] into a 7818 [18v regulator] would work.
Convention creates following, following creates convention.

Re: Voltage regulator in Valvecaster
« Reply #4 on: December 07, 2009, 11:10:50 AM »
He wants to use an18vdc supply but the circuit is 12v so I figure I can internally regulate it. Problems would only arise when he tried to run it off a 12v supply somewhere down the track

Re: Voltage regulator in Valvecaster
« Reply #5 on: December 07, 2009, 12:15:38 PM »
Surely someone can answer the question "Do voltage regulators introduce noise into effects circuits?"

kurtlives

Re: Voltage regulator in Valvecaster
« Reply #6 on: December 07, 2009, 12:22:31 PM »
No

If anything they take away noise.

runmikeyrun

Re: Voltage regulator in Valvecaster
« Reply #7 on: December 07, 2009, 02:49:59 PM »
just remember to filter it properly so that you don't introduce HUM (not noise) into your circuit.
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Re: Voltage regulator in Valvecaster
« Reply #8 on: December 08, 2009, 12:20:01 AM »
just remember to filter it properly so that you don't introduce HUM (not noise) into your circuit.

Caps to ground?

Renegadrian

Re: Voltage regulator in Valvecaster
« Reply #9 on: December 08, 2009, 01:24:37 AM »
You must have two voltage inside - 12V to power the heaters (and that's unchangeable) and B to the plates.
B can be 12V too (and it simplifies things) or higher (so you have to separate it from the heater supply)
If I'd be in your shoes, I'd go with a power in of 18V - then one wire to the heatsinked 7812 to provide 12V for the heaters and another wire with the 18V going straight to the plates.
Done an' workin'=Too many to mention - Tube addict!

Renegadrian

Re: Voltage regulator in Valvecaster
« Reply #10 on: December 08, 2009, 01:50:53 AM »
Maybe it helps...That's how me and some other men do...

Done an' workin'=Too many to mention - Tube addict!

Re: Voltage regulator in Valvecaster
« Reply #11 on: December 08, 2009, 09:41:30 AM »
Thanks Adriano, that's very helpful!