Enhancing Transistor Noise ?

[petemoore]

  Would the noise remain about the same when running a transistor at twice the voltage [ changing the supply from 9v to 18v]?
  Is it the diode bridge where leakage occurs?
  IIUC it is increased current output, [with no input] allowed through the Emitter Collector which causes a transistor to be noisy

[R.G.]

Noise isn't that simple. It varies with the source impedance the transistor base is driven from as well as the current through the base-emitter, and with how much gain the equivalent base input noise is amplified by.

Noise will remain about the same for doubled power supply voltage, other things (like bias current and source impedance) being equal. For most of the range of collector currents, collector current doesn't have a whole lot to do with it.

[Paul Perry (Frostwave)]

Pete, are you trying to increase or decrease the noise?
(in any case, it's a function of current, not voltage. Not a siimple function, mind.)

[petemoore]

  I have a noisey BMP, Ge transistors, PNP...there..I said it.
  I have FF's that are less that 'quiet', even with the guitar rolled off some.
   Having 4 transistors makes it a bit 'tasky' to find which ones of the four are noisy, I could go through alot of swaps to find out which of my candidate Q's make the least noise in the BMP.
  Also my test amp where I like to work is noisy and not really clean/loud enough to exhibit the noise 'unmasked' by it's own contributions...
  I was being cryptic or not completely inclusive I suppose...if I had a 'transistor noise' enhancer circuit [as opposed to a noisy circuit around the Q], I think I could find the noisy ones...