WNG noise toaster
WNG noise toaster
Hi all, dunno why but wng's always seem to give me problems. If anybody could help me diagnose and fix I'd much appreciate it.
Anyhow, I have this breadboarded but am not getting white noise sound from Q6-C. In fact no sound. In hz i get random frequencies the most common being 3.3hz (ish). I have swapped in and out transistors etc but to no avail.
9v in (8.9 at test)
Here is the leg readings.
Q2: C = 8.9v. B = 0.56v. E = ground
Q5: C = N/C. B = ground. E = 8.11v
Q6: C = 8.15v. B = 0.56v. E = ground
And here is the schematic.
Thanks all
Darren
Anyhow, I have this breadboarded but am not getting white noise sound from Q6-C. In fact no sound. In hz i get random frequencies the most common being 3.3hz (ish). I have swapped in and out transistors etc but to no avail.
9v in (8.9 at test)
Here is the leg readings.
Q2: C = 8.9v. B = 0.56v. E = ground
Q5: C = N/C. B = ground. E = 8.11v
Q6: C = 8.15v. B = 0.56v. E = ground
And here is the schematic.
Thanks all
Darren
Re: WNG noise toaster
This is a very common circuit for generating white noise, and it relies on the zener-type effect of running the reverse-biased BE junction of Q5 at virtually a constant current of a few micro amps. This is followed by two stages of amplification in Q2 and Q6.
The collector voltage of Q2 looks suspicious - it is at the supply potential, and the presence of R9 should drop the observed collector voltage down a bit. Check all connections, then Q2 and if it is OK, try reducing R10 to turn Q2 on a bit further. Aim for the same collector voltage as Q6.
White noise sounds like a gentle hiss, with a perceived (but not real) pitch of a few KHz - where the ear is most sensitive.
The collector voltage of Q2 looks suspicious - it is at the supply potential, and the presence of R9 should drop the observed collector voltage down a bit. Check all connections, then Q2 and if it is OK, try reducing R10 to turn Q2 on a bit further. Aim for the same collector voltage as Q6.
White noise sounds like a gentle hiss, with a perceived (but not real) pitch of a few KHz - where the ear is most sensitive.