PNP Transistor Projects

[stevics]

I have inherited a number of Germanium PNP resistors. Are there any recomended projects for them. I have already built a Rangemaster Type Treble Boost. Types OC71, GET113, GET536. Cheers.

[swever]

Fuzz face is an obvious suggestion. I have just finished building a positive ground one with soviet nos low-hfe trannies I grabbed recently in a local flea market. I've designed a pcb layout for it and it seems to work fine. I may post it here if you are interested. It's not that there aren't enough ff layouts, i know. Mine is different in that it allows to use a LARGE film input capacitor.





Also, I am working on a PNP version of zvex mastotron.

[Fancy Lime]

Hi Stevics,

the only area where Germanium PNPs are still used intensively are fuzzes. For several reasons, some of which are good, very good even, and some of which are stupid. "Hendrix had one" is not a good reason for building something for yourself or a fried, imho. But it can be a very lucrative reason for building something for sale. If I had your "problem" of being stuck with a bunch of Ge PNP transistors, I would search the internet for "Germanium PNP Fuzz" and spend a long time reading the hundreds of pages on this topic.

In either case, I would suggest that if you build something for practical applications, use a negative ground circuit. Any PNP fuzz can easily be re-designed to work that way. It allows you to use a common power supply with other stomp boxes. If you build it wth positive ground then you need to run it on battery or with its on supply (or together only with other positive ground circuits) because almost all modern pedals are negative ground. Contrary to what some people believe, you o not need a charge pump that converts + to - for this, just some knowledge on how a transistor works. See Jack Ormans article "Positive Power for the PNP Fuzzface" on AMZ-FX for how to do this.

Cheers,
Andy

[stevics]

Cheers swever and Andy

Swever, I would be interested in seing those layouts.

Andy. Thanks, makes good sense.

[swever]

Here's the layout for toner transfer

[swever]

...and the components placement diagram

[swever]

You may want to adjust the 33?k resistor value to get about 4.5V at Q2 collector when the bias pot is at 12 o'clock. In my build 33k worked almost perfectly so I let it be - gives a great range.

One thing I need to mention is that with 500k volume pot I have been getting a big difference in brighness depending on voulme pot position - lower volume give darker sound. I have not yet found a solution for that,  really.  I changed the pot to 250k and it helped a bit, but there still is quite a difference. I am not sure if it has to do with the transistors or something else - I think my silicon ff does not have this "feature". Maybe a treble bleed cap shall help. I am yet to experiment with that. Maybe I should start enother thread on this topic...

[Plexi]

EQD Crimson Drive.
One of my favs

[stevics]

Here's the layout for toner transfer

Hi I cant see any images or attachements not sure if I have a settings problem

[Plexi]

Here's the layout for toner transfer

Hi I cant see any images or attachements not sure if I have a settings problem

Only the 'pure' people can see it... sorry. (¿)

On-topic: me neither 

[swever]

Hi I cant see any images or attachements not sure if I have a settings problem

Dammit! These links should work:
https://drive.google.com/open?id=0B_LVUlh-0Wv8YlhEVDBKb2dCOG8
https://drive.google.com/open?id=0B_LVUlh-0Wv8SGs1MGx3dHY0QWc

[stevics]

That works, thanks

[swever]

http://effectslayouts.blogspot.ru/2017/08/tortenmann-ta-100.html

Today's update on effectslayouts. Looks and sounds interesting I think.