I ran across a couple of Geiger counter circuits while preparing the Carl & Jerry books a few years back, but it wasn't until I went looking in Google Books for other articles that I got a sense for the time period 1950-1960, when there was a certain Uranium madness in the air. At first it was about prospecting, but later on as the 50s drew to a close, it was mostly about fallout.
There were articles not only on building Geiger counters, but also reviews of commercial units and practical tips on how to search for the minerals. Sometimes it was a cover story (as with Popular Electronics for July 1955; scroll down) but mostly it was just a part of the electronics hobbyist zeitgeist in that era. There was a certain grim exuberance about it all: The evil Soviet Union was breathing gamma rays in the faces of our collective cultural consciousness, and we were ready to respond with our archetypal American can-do spirit. Some of us understood that the unspoken clause after "duck and cover" was "and die." Most, I think, did not. (Especially naturally optimistic 11-year-olds like me who just wanted to build a cool gadget with a Geiger tube he already had.)
So below is a list of the construction articles I've discovered for Geiger counters in the 1950-1960 era. Many are on Google Books, and I've posted the circuits from a couple of the others. If you have any more not listed here, please pass along links or scans so I can add them. I'm considering a standalone Web article for my Junkbox site on building "legacy" Geiger counters based on my current experience, so whatever you have that might be relevant, please share.
- Popular Mechanics, February 1949: "How to Build a Geiger-Muller Uranium Survey Meter". Brute force power supply consisting of three 300V batteries in series! Uses K-EX GM tube in series with headphones. No audio amp.
- Popular Mechanics, July 1950: "Uranium Survey Meter With Audio Amplifier." Much like February 1949 PM item, plus an audio amplifier. Uses CK-1021 GM tube (others are suggested as usable) and a 3V4 battery miniature tube for audio, which requires a 1.5V filament supply and a 45V plate supply.
- Popular Science, April 1955: "Prospecting with a Geiger Counter." Uses a CK-1026 GM tube, with HV generated by a pushbutton interrupter. 3S4 tube audio amplifier. Basically the same circuit as in Alfred Morgan's Boys' Second Book of Radio and Electronics.
- Popular Science, May 1955: "Super Geiger Counter You Can Build." Ambitious circuit with six (!) GM tubes in parallel plus a 2-tube audio amplifier, and a vibrator high-voltage supply. The GM tubes are all Anton 310 units. Has an averaging count meter.
- Popular Electronics, July 1955: "Home-Built 700V Geiger Counter". Two circuits, both using batteries (300V + 67.5V) in a simple voltage doubler. (No sparks!) One circuit has no audio amplifier, and the "deluxe" circuit has a 3S4 tube audio amp and an averaging count meter. Both use the Victoreen 75NB3 GM tube.
- Popular Electronics, June 1956: "Simple Transistorized Geiger Counters". Calls out either a CK1026 or a Victoreen 1B85 GM tube. Three circuits: two using 300V batteries, and a third with a pushbutton interrupter for HV. Tube audio amps are replaced by transistor amps, using general-purpose devices (2N35, CK722) that are not critical.
- Popular Mechanics, March 1957: "Prospector's Partner." A combination 4-tube battery superhet AM radio (with canonical 1R5/1U4/1U5/3V4 lineup) using a 1B85 GM tube patched into the grid of the first audio stage. Uses a pushbutton interrupter HV supply for the GM tube; 67 1/2 V battery for the radio.
- Popular Electronics, July 1957: "Geiger Gun". Compact gun-shaped hand-held counter counter using a CK1026 GM tube, pushbutton interruptor, and 2N107 transistor audio amp. Article is not online, but there are images of the counter as built in a junction box by someone here. (Scroll down.) Circuit is here.
- Popular Mechanics, August 1961: "Treasure Finder's Pal." A combination metal detector and geiger counter. Uses a CK-1026 GM tube and a CK-722 transistor oscillator into a universal output transformer to generate HV. GM tube output is patched into a transistor radio for audio amplification.