Author Topic: Voltage regulator in Valvecaster  (Read 3240 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.
An old man in a doom band.  Kinda depressing.

Likes: old motorcycles, old music
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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!

suncrush

Re: Voltage regulator in Valvecaster
« Reply #12 on: February 08, 2017, 06:52:25 AM »
I realize I'm necrobumping this, but it's the first google hit for "regulator circuit valvecaster."

IME, a regulator is unnecessary.  Simply using a 36 Ohm, 2 W resistor to drop the 18 V input to 12.6V for the heater circuit is adequate.  It's simpler, it doesn't generate more heat than the circuit can handle, and it's plenty quiet.

Another option, if you're interested in increasing headroom, is to use a 12V adapter, run the power directly to the heaters, and use a voltage doubler to supply 24 V to the plate.

GibsonGM

Re: Voltage regulator in Valvecaster
« Reply #13 on: February 08, 2017, 06:59:05 AM »
I realize I'm necrobumping this, but it's the first google hit for "regulator circuit valvecaster."

IME, a regulator is unnecessary.  Simply using a 36 Ohm, 2 W resistor to drop the 18 V input to 12.6V for the heater circuit is adequate.  It's simpler, it doesn't generate more heat than the circuit can handle, and it's plenty quiet.

Another option, if you're interested in increasing headroom, is to use a 12V adapter, run the power directly to the heaters, and use a voltage doubler to supply 24 V to the plate.

Good call. 
Bearing in mind to measure the adaptor output and consider its rating and voltage before you connect it to the heaters (could be unregulated). IE, "12V/500mA" could be quite a bit higher voltage at 150mA (or 300mA if you go that route) if it is not regulated, requiring more 'resistor tricks'.


MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

suncrush

Re: Voltage regulator in Valvecaster
« Reply #14 on: February 08, 2017, 07:32:05 AM »
Yes, and a tube breadboard device is a good way to do that.

I made my own:


GibsonGM

Re: Voltage regulator in Valvecaster
« Reply #15 on: February 08, 2017, 12:24:58 PM »
Hey, that is definitely cool - simple, don't have to buy anything!  I like it!!  :) 
MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

PRR

Re: Voltage regulator in Valvecaster
« Reply #16 on: February 08, 2017, 07:26:00 PM »
> a tube breadboard

An HONEST BREADBOARD !!

I can almost smell the crumbs!

Thank you for saving our traditions.
___________________
For ultra-traditional, use Fahnestock clips. They are going out of style since I was a pup, but they are around if you hunt. HH Smith is very good and very over-priced (>$1 each). Cheap no-names seem to sell for more in tiny lots.
« Last Edit: February 08, 2017, 07:30:53 PM by PRR »

sajy_ho

Re: Voltage regulator in Valvecaster
« Reply #17 on: February 08, 2017, 09:03:01 PM »
I realize I'm necrobumping this, but it's the first google hit for "regulator circuit valvecaster."

IME, a regulator is unnecessary.  Simply using a 36 Ohm, 2 W resistor to drop the 18 V input to 12.6V for the heater circuit is adequate.  It's simpler, it doesn't generate more heat than the circuit can handle, and it's plenty quiet.

Another option, if you're interested in increasing headroom, is to use a 12V adapter, run the power directly to the heaters, and use a voltage doubler to supply 24 V to the plate.
+1 to that, tubes sound better with higher plate voltage.
Life is too short for being regretful about it.

GibsonGM

Re: Voltage regulator in Valvecaster
« Reply #18 on: February 09, 2017, 04:36:24 AM »

+1 to that, tubes sound better with higher plate voltage.

They're made to operate at MUCH higher voltages, so running them down here makes their load lines basically useless...no headroom...little dynamics...so yes, getting them over 100V is much better, IMO!   Unless of course we can get some tubes meant for 12V operation  :) 
MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

rutabaga bob

Re: Voltage regulator in Valvecaster
« Reply #19 on: February 09, 2017, 04:46:13 AM »
That would be the 12U7...
"...as sharp as a sackful of wet mice" - Foghorn Leghorn