Alfred P. Morgan One Stage Audio Amplifier

    Back    Page 1 Page 2 Page 3    

Fake CK722 transistor
It's a FAKE!
It's a real Germanium transistor, but not a CK722. I made it out of a piece of wood and ten coats of spray paint.
The transistor is a
TUNGSRAM AC125, bought on ebay from a guy in Bulgaria.
Here's the wooden stick I used. The original plan was to mold a CK722 transistor out of epoxy. I stuck the carved stick into a lump of home made clay, dropped in a transistor and filled it with J. B. Weld. When that didn't work I tried modeling clay and epoxy. After several failed attempts I gave up, cut the end of the stick off and drilled a hole in it.
transistors in epoxy
It ALMOST worked! Here are the AC125 transistors in the epoxy. Dang, so near and yet so far.
These are real ones. I based my fake one on these pictures. Mine looks a bit clunky and I suspect the real ones are smaller. According to legendary small set designer Mike Peebles, "Just about any Germanium PNP Transistor will work in place of a CK-722. Most will likely work better..."

Raytheon CK722
When the book was printed in 1957, a CK722 was $2.20. That's more than $20 today. What kid reading this book had $20 for a single transistor?? Ironically, today you can buy 50 transistors for $2.20, but an actual CK722 will set you back $50.

So how much would a modern transistor cost in 1957? $2.20 in the year 2020 would be worth 24 in 1957. 50 transistors for 24 is about 4 for a penny.

Morgan radio and amp
So what is this and what does it do? It's an audio amplifier for a crystal radio. It doesn't make the radio work any better but it makes it much louder, which gives the illusion the radio works better.

Morgan radio and amp
There is no on/off switch. Connecting the headphones completes the circuit. The volume is VERY loud on a strong station. You probably need three volts with a real CK722 but I think a single dry cell would work fine with a modern transistor. As a matter of fact, I was listening to the radio while taking these pictures because I could hear the headphones on the table.

A Raytheon CK722 was actually a repackaged CK718 that didn't meet specifications. They were also relatively expensive. The transistor used here cost $0.29 in 2017. Actually, they were 10 for $2.90, imported from Germany via ebay. I thought that was appropriate since they are Germanium transistors.

When I made a fake CK722 it wasn't much different than what Raytheon did, and it probably works a lot better.

Morgan states in his book that over 10 million transistors were manufactured in 1956. A typical, run-of-the-mill Quad core i7 microprocessor contains 731 million transistors. Using 1956 technology, it would take 73 years to make the transistors for ONE core i7 microprocessor.

Here's the schematic. Morgan said to connect the amplifier to the radio through a capacitor, so the capacitor was built onboard the amplifier. It didn't work! The sound was very distorted, so it was removed.
A crystal set, the Morgan amplifier and a pair of Superex "Sensiphone" Featherweight made-in-USA "quality" headphones. (That's what it says on the box.) I was able to remove the ground wire and still pick up stations with plenty of volume. In this case, the coupling capacitor WAS needed. I guess Morgan didn't include it on the chassis because the need for it varies among different crystal radios.


Morgan's radio books were written so you had to read them and think about what you are seeing, For instance, in one rendering the positive wire is on the left and in the other it is on the right. Which is correct? You have to look at the schematic, then you learned the schematic symbol for a battery and a resistor and a transistor. Also notice on the left are two 1.5 volt cells, but on the right is a 3 volt battery. More than one cell is a battery.