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The photograph is a 1955 publicity shot showing Larry Cassingham holding a DG-2.
Detectron specialized in the manufacture of radiation detection equipment such as Geiger counters. It was immensely successful, as thousands of amateur prospectors searched for uranium and other elements in the post World War II era.
In the early 1950s, Larry Cassingham worked in the sales department for the Goldak company in Glendale, California. Goldak made products designed to detect underground objects such as cables, pipes, leaks, and such. Cassingham began to notice a growing number of inquires about whether Goldak also carried Geiger counters and similar radiation devices. After all, the Nuclear Age was then only a few years old. Seeing a tremendous business opportunity, Cassingham suggested to Goldak manager Fred Greenhalgh they expand their line to include Geiger counters. However, Greenhalgh wasn't interested.
Undaunted, Cassingham raised some capital and left Goldak. He, and electronics engineer and friend Jack Rondou, founded Detectron in North Hollywood, California. Recalls Cassingham, "Jack coined the name Detectronics for our company name. I suggested we shorten it to Detectron, and that's the name that stuck." Detectron's product line would include Geiger counters and metal detectors of various kinds.
While Cassingham concentrated on a network of sales dealers and promotion, Rondou concentrated on designing the company's core product: the DG2 Geiger counter. One obstacle was to design a circuit that would develop the nearly 1000 volt potential to operate the heart of the device: the Geiger-Mueller tube. Put simply, the G-M is a small tube, which contains a suitable gas such as argon, and a thin wire anode. The thin metal casing is its cathode. To operate it, the high voltage supply is applied. When the tube is placed in close proximity to a "hot" source such as uranium, the radiation causes brief, minute sparks between the casing and wire. Circuits in the Geiger counter amplify the sparks' pulses into audible clicks in headphones, and deflections on the needle of a meter, showing the "count", or number of pulses per second. The "hotter" the sample being read, the higher the count reading, and more rapid the clicks. (Here is a 56 kb .wav file of clicks produced by a thorium sample.)
When Detectron came into being, a portable Geiger counter was already available from Omaha Scientific, using three 300 volt batteries. The battery combination provided a stable source of the high voltage, but at the expense of making the instrument heavy and bulky - not necessarily what the amateur uranium prospector wanted to lug around in the desert! Rondou solved the design problem, and based his voltage-doubler circuit on the much-lighter 45 volt battery. (Remember, this was long before the availability of the three-pin voltage regulator chip!)
Their premier product was born. The DG-2 contained the G-M tube, battery and electronics contained in a compact unit. Later, the DG-7 was developed, which featured a belt clip, and a detachable "probe" that contained the G-M tube. At $98.50, Detectron sold over 20,000 Geiger counters, through dealers and direct sales, in three years' time. At its peak, Detectron had 125 employees.
To keep his radiation detection instruments accurately calibrated, Cassingham relied on the high standards kept at Los Angeles' Western Radiation Laboratory, operated by Dr Gordon Locher. Dr Locher is also known for pioneering the use of radiation therapy to battle cancer.
During this time, Detectron invented a new product, and Cassingham coined its name -- the nucliometer. A bigger but still portable device, it could detect radiation from large sources from farther away. One could search from the shelter of the car, or even from low-flying survey aircraft. In the 1950s, it was a long time before today's GPS and other surveying satellites. Howcould someone detect ground-based radiation from a plane and then go back and find that spot once the plane lands? "Easy," smiles Cassingham. "You'd fly in a systematic pattern over the area you're interested in. When you got a positive reading on the nucliometer, you'd drop a sack of flour out the plane window. Later, you'd drive back to the area and look for the big white flour spot!"
Cassingham recalls "back then, everyone was interested in our instruments. Once, we were docked in a friend's sailboat, and I had brought along a nucliometer. A man came over from another boat in an adjacent slip, and asked us a lot of questions about it, what it did, how it worked, and so forth. The man was Humphrey Bogart.
"Speaking of actors, another time, I was in my office when someone knocked at the door. I looked up and it was Clint Eastwood. Boy, his presence sure excited the young ladies in the office!"
The late Robert Strauss, and Mickey Rooney clown around with a model DG-7 Geiger counter in this publicity still for Republic Pictures' 1954 sci-fi film "The Atomic Kid"
"We even made it into the movies back then," continues Cassingham. "They used Geiger counters as props in many sci-fi films. Next time you see an old movie about a radioactive monster, meteorite, or atomic fallout, watch for our Geiger counters. Sometimes they'll show a close-up. In movies such as The Brain From Planet Arous, you can see the name Detectron when they show the count-meter reacting to the radiation.
"I also served as Technical Director on some films, such as Zombies from the Stratosphere with Leonard Nimoy, and The Atomic Kid with Mickey Rooney. I remember arguing with various movie directors, as they often wanted more drama at the expense of technical accuracy."
By 1956, the uranium boom was pretty much over and radiation detection equipment was in much lower demand. However, the other metal detection products in the Detectron line were still selling well.
"I received an urgent call from a manager at Los Angeles International Airport," Cassingham remembers. "Seems they were having a problem with a segment of runway lights, and wondered if any of our detectors could help them locate a broken power conduit. I drove down there with a Model 505 Pipe and Cable Detector, and found the problem pretty quickly. I don't remember what caused the break, but I remember my fee: $150!"
Detectron did have a "first" of sorts, in one of its products. That product, a transistor AM radio, was the first such radio that used standard, commonly available batteries: D cells.
Though a talented businessman, Cassingham's education and career began in the journalism field. Both to provide an outlet for his creativity and to promote Detectron products, he started a periodical Outdoor Times, which had many subscribers in the field of prospecting. It contained photos and articles on the hobby, and of course news on the latest Detectron products.
Cassingham and Rondou eventually branched out into other fields, including making testing equipment for another new field, computers, with the company Computer Measurements Corporation. They sold the Detectron name and business in 1965 to Tinker and Rasor, who still have a line of Detectron products.
Cassingham eventually got back into the metal detector business as Rayscope.