Negative voltage regulator

Started by served, April 08, 2010, 06:01:40 AM

Previous topic - Next topic

served

Hi.

I was just reading a thread one day, and started to think, how to solve that biasing issue in Fuzz Face Germanium, or other pedals with germanium transistors.
I looked through some electronic catalogues and things, but I could not find a way to keep the bias constant.
Has anyone made a breakthrough? Somekind on chip or regulator? It would be a huge step, if you wouldnot have to think about bias anymore.

A.

GibsonGM

I'm sure it could be done to some extent with comparators etc., altho many of the device parameters change differentially as the temperature drifts.  So the required bias wouldn't follow a linear path to yield the same results, if that makes sense.   

In the end, it seems like it would be a very complicated undertaking on one hand, but not so hard on the other provided you weren't looking for the performance to remain the same.  I hope R.G. gets into this one, thermal stuff is wild and well beyond the scope of most of us mere humans! 
  • SUPPORTER
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...

served

Temperature is on tough thing. Cant get through it and over it. But it would be really cool thing to achive.

slacker

Have a look at John Hollis's Rock Face http://www.hollis.co.uk/john/circuits.html that's the nearest I think anyone has come to attempting to solve the problem.
There is another fuzz face type ciruit that used a bias pot but added an LED that showed you when it was correctly biased, I can't remember what it's called though.

slacker


Nasse

Found this in wikipedia

"For critical applications the quartz oscillator is mounted in a temperature-controlled container, called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation by external mechanical vibrations."

Such circuit could be made inside a big enough water container with enough thermal inertia to get trough few hours in extreme hot or cold environment. Perhaps Eric Johnson would buy one.
  • SUPPORTER

served

Actually, First I considered a heatsink for germaniums, but if the room temp changes, then it doesnt work any more.