Which trim pot for RangeFinder?

T

timbovee

New member
Hi folks,

I'm considering a RangeFinder for my 4th or 5th PedalPCB build. I've loved Robert's stuff from the very beginning, including my recently completed Son of Ben.

I'm great at following directions, but don't know as much about electrical theory as I'd like. For this reason, the build documentation for the RangeFinder stumped me, as it has the bias trim pot listed only as "GE PNP" which is "is typical Germanium PNP spec’d for Rangemaster type circuits." Huh? Is this so obvious that I sound dumb asking? Or is the trim pot value perhaps dependent on the transistor I use?

While I have your attention, I'm hoping I like the RangeFinder as much as my Beano Boost, because I wouldn't mind replacing it and selling the Analogman pedal to help fund a new guitar purchase. Have any of you tried the RangeFinder and Beano Boost side by side?

Many thanks
 
There will be several guys who will have more knowledge than I who will reply here but what I have learned from them is that the measurement of the PNP Germanium transistor is more important the type. There is recommended specs for a Range Master treble booster that is searchable here and on the internet in general. I was looking into this a couple months ago as I am thinking of building the Rangefinder too this year.

The trimmer is listed on the build doc as 5k. I assume another value would work with some trade offs.
 
From Aion docs, pick an hFE between 65 to 100, and leakage < 300μA.

This circuit is pretty forgiving though, I tried some in that range, but ended up using an hFE of 130 because it sounded just as good.
I used a 10K bias trimpot.

Although I haven't tried a Beano I suspect one you build should sound just as good.
 
You must log in or register to reply here.
Back
Top