rewire pnp to npn -Rangemaster

[guavatone]

I am trying to rewire a rangemaster schematic to get an understanding of how to use a npn transistor in a schematic that calls for pnp.  I can't seem to get it.  I reversed the polarity of the caps and battery.  Do I need to flip the transistor Emmiter and Collector?

Keep base the same?

does the 10kohm pot get rewired?

Thanks in advance.

[vanhansen]

Check this out.  http://fuzzcentral.tripod.com/rangemaster.html

Phillip did a nice job on this one.

[guavatone]

Wow! thanks for the link

[vanhansen]

No problem.  Let us know how it goes for you.

[guavatone]

I tried the npn rangeblaster with what I thought was  BC 546B -npn transistor.  When I tested I was overloading the Transistor and getting Solid state crunnch from my strat.  hmmm.  I then reversed the transistor and it seemed to work right and give me clean gain to drive my fender champ into nice tube crunch.


Is there anyway to tell if i have pnp or npn tranies?  

I also used some substitute values eg.... a 1N4148 for the 1N34A and a 100K instead of 470 k resistor.

Any thoughts.




BTW I put angela caps -SCR 2.2uF and they wound nice compared to panasonic pollyprops.  sprague orange drops sound nice too but not as full as the Angelas, I think they are the same as Solen  FastCaps.


Thanks

[guavatone]

Ok it is a npn but from the spec sheet picture it looked backwards to what seems to be working right.

the Hfe on these are 260 to 317.  is there a prefered hfe value?

[phillip]

If you're building it as Silicon, you can just remove the diode that's across the base-emitter of the transistor.  That diode helps prevent a Germanium transistor from suffering thermal runaway, which makes it sound very bad and eventually the transistor will "turn off" until it cools down again (the same problem that the Fuzz Face and a lot of the ToneBenders have).  

If you end up building it with a NPN Germanium transistor, that diode also has be Germanium since a Silicon diode won't keep the transistor from having thermal problems.

RG Keen has a good article over at GEOFEX (www.geofex.com) about the Dallas Rangemaster and transistor selection and tuning for it.  A low leakage Germanium transistor with a gain of around 70 works best in the circuit with the original resistor values.

Hope this helps some
Phillip

[guavatone]

Funny... I just built a design based on YAFF fuzz face with the same trannies and they had to be reversed ( in comparisson to the rangemaster link)  to get distortion.

I thought the rangemaster was a "clean" effect...am I missing something?

[AL]

The Rangemaster will color the sound  a little bit. It may also push your amp into overdrive - depending on the amp and how you set the pedal. If you want a clean boost check the AMZ Mosfet Boost.

AL