Turns out that it’s not too hard to find NOS AC125 transistors. They were used in a 1960’s era guitar effects pedal called the Fuzz Face. If you’ve ever heard any Jimmy Hendrix, you’ve heard a Fuzz Face. The original version had two NKT275 germanium transistors, which is very similar to the AC125 (in the list above, in fact). The germanium transistor was very sensitive to temperature and the sound would change as the temperature varied, so later models went to silicon transistors, but those just don’t sound as good to expert guitar players, so many players modify the modern units to use germanium transistors and the transistor of choice is the AC125, so there are many places that have acquired old stock and sell them at a reasonable price, often in matched pairs. I picked up a pair on eBay for about $10 with shipping.

Since Michael is generously sending me a new block and if I can fix this block, it would be interesting to see if I could build a Fuzz Face with the Lectron blocks. It’s just a simple two-transistor amplifier, though I would need more resistors, one more capacitor, and the potentiometers are different.

Sometime in 1968 I saw an advertisement for the Raytheon Lectron set. I don’t recall where, but we were subscribing to Popular Electronics at the time. I’m sure I was rather a pest about it and it was under the tree on Christmas morning in 1968. I was nine years old. My most distinct memory of that time was building the oscillator circuit and my dad explaining how an oscillator works. I’m sure I built everything in the book many times. I had the set until college, but lost it somehow moving around at the time.

I always knew I wanted to work with computers. I started in Electrical Engineering in college, but switched over to Computer Science. I worked in both hardware and software over the years, but haven’t done much hardware in a long time now other than as a hobby. I’m now a Computer Science professor at Michigan State University.

I have two young grandsons. Luke is 5 now and it won’t be long before I can introduce him to the wonders of electronics.

I love the technologies of the 60’s. In addition to the Lectron set, I have a DEC H-500 Digital Logic Lab. I would love to know what that thing cost in 1968 when it was built. I also have an EAI TR-20 Analog Computer that I restored and which is completely operational.


  • This reply was modified 2 years, 5 months ago by Michael. Reason: Changed font and size styling for easier reading