H. P. Friedrichs (AC7ZL) Homepage





My Books 

My Books

Instruments of Amplification

Gallery 2

Here, you can take a look at images associated with the projects appearing in Instruments of Amplification.

The Tennis Ball Triode's base is composed of a cheap, glass ashtray. Look at the pretty blue


An improvement on the Tennis Ball Triode is the "Beehive Triode," depicted here. In this tube, the grid assembly is anchored to the envelope of the tube, not the base. The terminal for the grid projects from the top of the tube.


This shows the beautiful blue "Beehive" all lit up.


What's this? Would you believe that it's a triode with no grid? This device is modeled after the "Weagant" tube of the 1920's. The control signal is applied to the copper foil on the exterior of the tube.


These are parts for a future triode. At the top is a glass tube taken from a hamster water bottle. Below it are two grid assemblies wound from copper wire. At the bottom, you can see two filament assemblies that have been harvested from electric lightbulbs.


This is another view of similar parts as they are assembled to become simple triodes.


Folklore suggests that amplification may have been observed in mineral crystals many decades before the official invention of the transistor. Here, I'm exploring that idea with a fragment of purified silicon.


The first commerically available transistors were point-contact devices. This picture represents two different types of home made point-contact transistors. The body for the device in the center was fabricated from an old relief valve. The other two are fashioned from common plumbing parts.


The action of the point-contact transistor relies on the precise placement of its internal electrodes. This is a photomicrograph of the emitter and collector electrodes in one of the transistors shown above. The vertical wall at the left of this image is the germanium die. The points of the electrodes to the right rest less than 0.002 inches apart.


One way to test germanium crystals and different electrode materials is to use an open-faced "breadboard" approach. The experimental transistor shown in this image rests on the stage of stereo microscope, an accessory that helps a great deal in the proper positioning of electrodes.


Here we see two experimental junction transistors based on cuprous oxide. I experimented with two versions. While similar in overall construction, the first one features a comparatively thick base region which is narrowed through mechanical means. The second was fabricated onto copper foil.


Here's a better shot of the foil-based cuprous oxide transistor. The base region is a 0.002 copper film mounted to a support hoop. Cuprous oxide, applied to both sides of the film, form the emitter and collector. Electrodes are anchored to the oxide with tiny dots of silver-bearing ink.


This is another shot of the same transistor, but it depicts the other side of the PNP sandwich. Note that the plastic cover has been removed.


Click here to return to Gallery 1


(revised - 11/03/2005)