Alfred P. Morgan One Stage Audio Amplifier

    Back    Page 1 Page 2 Page 3    

Now let's think about this.

֎ Why do we have a resistor with long leads floating in the air when it can swap places with the green wire?
֎ Why have an output clip in the middle of the board when it can be moved to the right to match it up with the other one?
֎ Why have 3 volts DC going through your super sensitive high impedance headphones??

We can use a resistor in place of the headphones, then pick the audio off the collector of the transistor with a capacitor. That would get the 3V DC out of the headphones but then we need an on/off switch. Since we need to add a switch, why not add a volume control?

What value resistor should be used to replace the headphones? I don't have any real knowledge of electronics, so I can't calculate it. I do, however, have a cool meter my buddy Joe gave me for Christmas. The DC resistance of the headphones is about 3.98 K Ω, so a 3.9K resistor will take their place. (Those headphones are supposed to be 4K. Somebody owes me 20 ohms.)

Original schematic and the new schematic with the four parts added.


Morgan Amp rebuild
I had to work carefully because Alfred P. Morgan may be watching. Elmer Osterhoudt as well. I recently found out that the "O" in Osterhoudt is a long O. For years I have been calling him Ah-sterhoudt instead of Oh-sterhoudt. He spoke to me from the grave by way of one of his "MRL Radio Flyer" publications.


Morgan Amp rebuild
Here's the completed amplifier. Now we have a more serious rendition. We can turn it on and off, control the volume and the 3 volts DC no longer passes through the headphones.


Here's an ad for cigarettes!! Since they aren't allowed on TV, I thought I'd put one here. Come to where the flavor is, come to Marlboro country. Actually it's just there as a reference to show the size of the amplifier.

I had hoped the amplifier would drive a speaker, but it does not. It's designed for high impedance headphones. The crystal set in this photo is from the same book, "The Boys Second Book of Radio and Electronics."


Burgess No. 7
Burgess No. 7
Six months after making the Morgan Amplifier I came across a cool YouTube video. The video showed a real set of Burgess No. 7 dry cells. It seems my reproductions are not up to snuff. I didn't notice that Morgan had rendered the red tops of the battery labels in his drawings. The good news is you will probably enjoy the video.

Eventually, the Duracell batteries leaked. The expiration date was still two years away, but those things leak in the package before you even buy them. Since the Burgess skins were ruined I made new ones using Ray-O-Vac batteries. Also, I had obtained a real CK722 transistor and some vintage battery holders.
The amp was built again with the correct transistor and the red tops on the battery labels. It even has the exact screws Morgan says to use.
Alfred Morgan transistor amplifier
Now it matches the picture in the book!