March 3rd, 2012, 10:41 AM
I have the stuff around to do a PTP Rangemaster clone, and two or three of a couple different germanium transistors. Is there a specific HFE range that will work best in this circuit? I know the values of the transistors I have on hand.
Also, I don't have an OC44 on hand...are there certain transistors that I definitely want to avoid even though I've seen a lot listed as suitable replacements? Since I'm going to build on a terminal strip I may just alligator clip a couple in to see which sounds best before soldering.
March 3rd, 2012, 11:28 AM
I'd say anywhere between 80 - 130 hfe. Shoot for a transistor with a gain around 100 hfe. With my experience anything lower than 80 lacked the ability to boost the signal as much as I wanted. However you may prefer something with less or more gain, there is no right or wrong, only perference.
In terms of transistor type, many will get the job done. Each one will sound a bit different from one another so you will need to decide on one that sounds best to your ears. Some may sound warmer or brighter, smoother or fuzzier, some may be more hissy than others.
March 3rd, 2012, 12:39 PM
Since I'm going to build on a terminal strip I may just alligator clip a couple in to see which sounds best before soldering.
I'd suggest using a socket. That way you can switch out transistors as much as you like, and you also won't have to solder them. The thought of soldering germanium transistors makes me nervous.
I wired mine PTP and used a socket, some gut shots are here:
The finished pedal, fwiw:
March 3rd, 2012, 01:49 PM
I think I have a socket, but I didn't think I would be able to attach the little PCB pins to anything to make them work. I'll have to check out your pictures on a monitor later on to see if your attachment method shows up better. That's why I was going for a ballpark HFE value and figured I would alligator clip different values and types into the circuit and only solder once.
I also intended to add the rotary switch as that's how the Colour Boost is set up. I know those have a 4-position Alpha switch. Where did you get yours from and what is the correct terminology (2p4t)?
I think I have AC128s from 65 through about 130 and three of something else in the same range from a Fuzzy Bee build. One transistor sounds better in that build, but if I use all three of that type I can barely turn the knob and have it be usable with a stomp switch due to the massive volume increase.
Thanks for the tips.
March 3rd, 2012, 08:43 PM
CV7003 (mil-spec OC44) are great transistors for Rangemaster clones.
Effects Connection and Small Bear have them available and already tested.
An added bonus with them is that they can be wired negative ground without issue usually so you can daisy chain it with your other pedals.
Any 1P_T rotary switch can be used for a capacitor switch, you don't need a dual pole. You can use a dual but you'll only need half of it so you are using it as a single pole anyway. Toggle switches can be used as well. A SPDT with the center position off (on/off/on) will give you 3 different capacitor selections.
The following are great capacitor switches. I've used both of them often.
This one is adjustable from 1 to 12 different positions. http://www.smallbearelec.com/Detail.bok?no=477
March 4th, 2012, 08:38 PM
Thanks for the Effects Connection lead. I had checked Small Bear for the OC-44 and they were out of stock. I just ordered a couple from EC. Good to hear about the adjustable switch. I had also seen that but wasn't sure of the quality.
March 5th, 2012, 11:13 AM
I'm pretty sure I got that particular switch from Small Bear, but I'm bought them from Mouser as well.
On soldering to the socket - I used small gauge (22 or 24 gauge) wire. Make a hook shape in one end of the lead, then tin it, then slip it over or around the pin on the socket and solder it. It helps to hold the socket in a vise or a little 'helping hands' alligator clip device.
This is the type of socket I use - image is from the Effects Connection site. The pins are small, but with a small gauge wire you can solder to them.
I have a CV7003 in mine, btw.
You probably don't need more than 2 or 3 positions on your switch. I did 6 more as an experiment than anything. I found there's really only a couple of them I really use.