Radiological dosimeters are electrostatic devices used for measuring an accumulated dose of radiation. The civil defense dosimeters are a standard dosimeter design. This same type of dosimeter would be used anywhere people would have to measure their accumulated radiation dose.

Standard Civil Defense Dosimeters

	CD V-138 Dosimeter Range 0-200 Milliroentgens Reads Gamma Radiation Low range dosimeter used for training. 221,866 produced.
	CD V-730 Dosimeter Range 0-20 Roentgens Reads Gamma Radiation Superseded by CD V-742. 168,500 produced.
	CD V-740 Dosimeter Range 0-100 Roentgens Reads Gamma Radiation Superseded by CD V-742. 162,950 produced.
	CD V-742 Dosimeter Range 0-200 Roentgens Reads Gamma Radiation 3,117,201 produced.

	New CD V-138 Dosimeter Range 0-200 Milliroentgens Reads Gamma Radiation Low range dosimeter.
	New CD V-730 Dosimeter Range 0-20 Roentgens Reads Gamma Radiation

Here is a sampling of some of the chargers I have in my collection. Top row left to right: Bendix 643 (CD V-750 Model 1), Jordan CD V-750 Model 2, Universal Atomics CD V-750 Model 3 and Bendix CD V-750 Model 5. Bottom row left to right: Jordan Electronics CD V-750 Model 5, Jordan Electronics CD V-750 Model 5a, Industrial Electronic Hardware CD V-750 Model 5b, and a FEMA issue S.E. INT'L Inc. CD V-750 Model 6. I have never seen any listing of a CD V-750 Model 4.


This is a CD V-750 Model 5b dosimeter charger manufactured by Industrial Electronic Hardware Corp. This unit is used, as seen in the picture at the top of this page, to charge (zero) the dosimeters before use. The dosimeter presses onto the charging contact on the upper left of the charger and the hairline on the dosimeter's scale is zeroed by turning the large knob on the upper right. The charging contact has a clear plastic bushing that the contact passes through. There is a light bulb inside the charger below the contact which comes on when the contact is pressed down and allows the person charging the dosimeter to see the scale while charging. You can see the markings showing which way to turn the knob, "up scale" or "down scale". Some of these chargers can be tricky to use and take quite a bit of practice to get a dosimeter zeroed on the first try. These chargers use one D-cell battery for power. Click photo to see larger.



CD V-750 Model 6
FEMA later released the CD V-750 Model 6, an electrostatic dosimeter charger in the early 1990s. Instead of using batteries this charger generates it's own charge to charge the dosimeters with a piezoelectric crystal. The dosimeter is charged by working the large black lever until the hairline moves down-scale past zero, then the hairline moves upscale slowly as the black button, just above the lever, is depressed. The button is released when the hairline reaches zero thus zeroing the dosimeter. The yellow trigger-like lever latches the dosimeter in place in the charger. I find it interesting that even though these were released by FEMA they still have the Civil Defense logo prominently displayed on the label. This Model 6 charger is very easy to use.
Special Thanks to Mike for this CD V-750 Model 6!!

FEMA CPG 4-1 AC Dosimeter Charger
The FEMA CPG 4-1 Repair and Maintenance Manual For Radiological Instruments Volume 6 Section 30 has instructions for building an AC powered dosimeter charger. The CPG 4-1 states that this charger was to be built and used by state maintenance and calibration shops. I thought it would be a cool project to try to build but it proved a bit more of a pain than I thought it would be. After it was all over and done with it was worth it though. The aluminum box enclosure is still available from the original manufacturer named in the parts list as is the power transformer but a new transformer was too expensive so I watched eBay for a few months and finally found a new one in the box for about $15. I was able to locate equivalent parts from the information on the FEMA parts list. The one thing listed that wasn't available was a modified charging contact. I robbed one out of a non-working CD V-750 I had and modified it as best I could without seeing the one that is listed on the parts list. I was pretty surprised when the thing actually worked when it was finished! It charges dosimeters easily and works pretty well overall. The box didn't come yellow, I painted it. If you want to try to build the charger here is an Adobe Acrobat PDF file of the instructions. CPG4-1ACCharger.pdf 400Kb file size.