DKP-50 dosimeter (radioactivity detector) tear-down

DKP-50 was a dosimeter produced for the Polish People's Army during the cold war era. It indicates amount of radioactivity absorbed by the body, a soldier was equipped in this device in case of nuclear conflict. A scale has range of 0-50R (R = Roentgen, a legacy unit of exposure of X-rays and gamma rays). 500R in 5h is usually lethal.

It's based on ionizing chamber that changes radioactivity radiation to an electric current, current discharges a capacitor that is also used as a power source. The device measures discharge of a capacitor over time. This is done by using a wire that accordingly changes its position and optic unit to make those results available for the operator.

If you're interested in radioactivity, you may also want to read about a Geiger–Müller Counter that I've made.

Sample result is visible on the picture. Note that it's inaccurate because the device was discharged and wasn't calibrated.

The deice, visible a plastic cap (with seal) to protect charging electrodes and a metal clip to attach the device to an uniform. On the cap, there're two names: "DKP-50" and "12".

One of the charging electrodes visible at the center, it needs to be pushed inside in order to be connected to the capacitor. This is done this way to minimize self-discharging of the device. Second electrode is connected to the aluminium body of the dosimeter.

An ocular is used to observe the results. It's hard anything if you wear glasses.


Below is a picture of all parts, from left: ocular, ionization chamber, capacitor, charging electrode.

DKP-50 all parts

An ocular with hand-made date engraved on it: 17.II.78.

DKP-50 optic unit

A capacitor 300p/300V, all data marked in Cyrillic alphabets. The capacitor is empty inside, it's because the light must go through it.

DKP-50 capacitor DKP-50 capacitor DKP-50 capacitor DKP-50 charging electrode


  1. A simple yet very smart device. Cold War has some interesting plots...