New mini-breadboard

[Chuck D. Bones]

Wouldn't hurt. Current draw is around 2.5mA. I wouldn't go any higher than 470Ω. I'll give it a try on the breadboard...

 

[Chuck D. Bones]

Make that 3.2mA. 700mV drop in a 220Ω resistor. Seems to work ok. I know you set the bias lower on yours so the current draw will be less.

 

[jubal81]

Make that 3.2mA. 700mV drop in a 220Ω resistor. Seems to work ok. I know you set the bias lower on yours so the current draw will less.

Dunno about yours, but what I've got on my board is eerily low noise.

 

[Chuck D. Bones]

Mine isn't "noisy" but it does pick up a lot of hum if I crank the gain. Once it's in a closed box that will all go away.

 

[cooder]

So would the PNP version possibly more susceptible to noise compared to the NPN? A question that nags my brain...
Also, regarding noise suppression, Peter Rutter uses inductors in some of his designs for that, would that be a good one to nudge in?

 

[fig]

Mine is dead silent. Probably due to the fact I haven't built it, but I haven't yet finished diagnosing, so I'm not going to commit to that possibility.

 

[Coda]

Mine is dead silent. Probably due to the fact I haven't built it, but I haven't yet finished diagnosing, so I'm not going to commit to that possibility.

You must have built the MXR noise gate instead…

 

[Chuck D. Bones]

So would the PNP version possibly more susceptible to noise compared to the NPN? A question that nags my brain...
Also, regarding noise suppression, Peter Rutter uses inductors in some of his designs for that, would that be a good one to nudge in?

I don't think the PNP version would be more susceptible. Either polarity requires clean 9V power.

Power filtering is as much empirical as it is analytical. Filter inductors won't hurt, but they may not help either. I have built a couple VFE boards and put in the 1mH choke. Was it necessary? I have no idea.

 

[Chuck D. Bones]

Mine is dead silent. Probably due to the fact I haven't built it, but I haven't yet finished diagnosing, so I'm not going to commit to that possibility.

Is there a typo in that sentence?

 

[fig]

Beyond several grammatical errors, the sentiment (a failed attempt at humor) seems intact.

I am not resigned to non-existence being a cause for silence?

 

[Chuck D. Bones]

To quote Henry Lloyd Moon, Jack Nicholson's character in the movie Goin' South: "A joke is when you make other people laugh."

 

[fig]

Just saw this! So true.

What is a joke if nobody laughs?

Useless

 

[Chuck D. Bones]

The bias trimmer is too sensitive, there needs to be a resistor at each end of the trimpot to limit the range. I like to set it between 1.0V and 1.8V.

 

[Chuck D. Bones]

See Chucks Boneyard for latest rev of the PNP design.

 

[Falterthethomist]

I know this thread is quite old - but is there any way to make this work for a single transistor setup such as the rangemaster? I found this thread somewhere else https://www.freestompboxes.org/viewtopic.php?t=23861 but it seems nobody really tested this.

Any ideas? Thanks

 

[Chuck D. Bones]

Yes, but it's not needed for a Rangemaster. The Rangemaster's bias should be stable enough on its own.

 

[PedalBuilder]

Yes, but it's not needed for a Rangemaster. The Rangemaster's bias should be stable enough on its own.

It would be useful for Q1 in a Tone Bender Mk II, though? That stage is leakage-biased and gets finicky when the temperature changes.

 

[Chuck D. Bones]

I'm not convinced that the TB mk2 first stage needs to be Germanium. If you're up for breadboarding, why not try a BMP first stage in place of the TB mk 2's first stage? Very stable bias and plenty of gain with the right resistor values.

 

[PedalBuilder]

I'm not convinced that the TB mk2 first stage needs to be Germanium. If you're up for breadboarding, why not try a BMP first stage in place of the TB mk 2's first stage? Very stable bias and plenty of gain with the right resistor values.

Sure, I can breadboard that and report back. I'll admit that a big part of what interests me is the cool factor, for lack of a better term, of having a temperature stabilized, all Germanium Tone Bender Mk. II, as opposed to having a hybrid circuit that is less temperature-sensitive, even if the hybrid sounds similar.

 

[Chuck D. Bones]

Do you want "temperature stabilized" or "bias stabilized?"

There is a difference.