In Episode 2, we talked about Module DCDC_3V3_400V – step-up voltage converter for Geiger counter with pulse output .
GGreg20 – one of the boards for amateur production (DiY) of radiation level dosimeters. This board includes the following functional units:
- The main power supply unit of the module – connectors, switch, mode switch (jumper) and linear stabilizer. This node is built so that the recorder can act as a master – slave power supply in relation to the controller.
- The high voltage Geiger-Mueller tube is supplied by the DCDC_3V3_400V module, which is mounted on the GGreg20 board.
- To mount the Geiger-Mueller tube on the GGreg20 board, three holders are soldered, on which you can install two types of tubes – SBM-20 (SBM-20) or SI-3BG. A number of SMD components provide a mode of powering the tube and removing pulses from the tube according to the number of particles entering the tube.
- The board has a buzzer and an LED for the possibility of autonomous use of the board as a radiation level detector. These alarms display data that allow you to calculate the level of radiation per unit time.
- The board has components designed to match the level of information pulses in accordance with the input requirements of the GPIO controller.
How to use the registrar without a controller? Our recorder, unlike radiation meters, does not have MCU and display , but has four very important properties:
- It is miniature and convenient to wear and use, can be mounted in a simple and inexpensive case;
- On the basis of GGreg20 it is possible to make times cheaper device in comparison with meters or its functional analogs;
- GGreg20 is many times more economical in terms of power. In the case of using a low-capacity AAA lithium battery (360 mA / h) will work without recharging and without turning off for tens of hours, and in the case of actual use (on – measured – off) – several months.
- Connect the power supply with a voltage of 3.4 to 5.5 volts and in 1-2 minutes you will be able to hear sound and see light signals from the “caught” particles.
Use Figure 1 to determine how to connect the board to the power supply.
A little physics – how to measure radiation levels.
Everywhere – on the street or indoors, clean or dirty – there is always some level of radiation. If there are no events related to radioactive contamination, your registrar will register background level . The eternal source of radiation is outer space, which “bombards” us with the intensity of the background level.
Mankind uses many different physical units in which the level of radiation is measured. That’s what happened. It is used in Ukraine X-ray or Sievert . The upper value of the background level is considered to be 30 microsieverts. Different types of Geiger-Mueller tubes, due to the design of each type, register different numbers of hits.
We installed the SBM-20 tube on the module. The limit level (normal exposure dose rate) of the number of particles registered by the SBM-20 tube is 60 per minute (formula: number of impulses * 0.0057 uSv / h), which is equal to about 30 micro X-rays or 0.30 microsieverts.
With an average background level, you will hear (and see) 20-30 pulses in one minute. This means that the radiation level around you is 0.1-0.15 microsieverts.
In the surrounding space, including the sun, all sorts of events occur, as a result of which the level of radiation fluctuates. But if you observe more than 60 pulses in one minute, then something has happened on Earth, or rather – in your place. For example, you were brought a “dirty” forest or stones. This means that it is time to beware.
You have similar questions – buy GGreg20
If such measurements are not very convenient for you, read and implement the solution proposed in the next episode. To be continued.