This project participates in the "Stars Program" outsourcing track of JLC. The topic was jointly released by Wuhan Xinyuan Semiconductor Company and Jialichuang. The project took two months to independently design a portable and rechargeable environmental radiation detector.

The electronic components used in this project can be purchased on Taobao, and the chip specifications are all packaged in 0805 for easy soldering (except for the thermistor in the charging part).

The project is divided into versions 1.0 and 2.0. Version 1.0 is for debugging individual circuits, suitable for the early stages of the project, while version 2.0 is integrated.

Sound and light prompts can be performed according to the size of the radiation value

It can be charged through a mobile phone charger without frequent battery replacement, protecting the environment.

Rich UI interface, users can intuitively see the relevant parameters of the current radiation amount

When the TYPE-C interface is plugged in, the power supply circuit is automatically replaced, and the entire circuit is powered by the charger while charging the battery.

2023.9.1 start the production of the project and start the construction of the simulation circuit.

2023.9.4 PCB board drawing is completed, but considering the difficulty of soldering and replication, give up decisively.

2023.9.17 PCB board drawing is completed, the PCB layout is a modular layout for easy debugging.

2023.10.10 PCB debugging is successful, start drawing V2.0 version.

2023.11.07 V2.0 version drawing is complete, start writing the program, and start printing the shell.

2023.11.17 finished

1. Use the conduction of the MOS transistor to realize a switching circuit, that is, when there is an external power supply, the output of the battery is automatically cut off, and the external power supply supplies power to the entire circuit while charging the battery.

2. The TP4056X lithium battery charging chip is used to charge the battery, and the charging circuit used in this project has temperature feedback. It automatically disconnects the charging when overheating to avoid danger. And compared with the TP4056, the TP4056X comes with reverse connection protection, which makes the external circuit more concise.

3. The SX1308 boost chip is used to boost the lithium battery from 4.2V to 5V, avoiding abnormal chip operation caused by low battery voltage. At the same time, this design makes the working voltage of the Geiger tube stable, avoiding counting abnormalities caused by low battery power.

4. Use Boost boost circuit with TLC555 to achieve boost, and adjust the duty cycle of the timer by adjusting the adjustable resistor to achieve adjustable boost.

5. Using AMS-117 3.3V LDO linear voltage reduction chip, the stabilized 5V voltage is reduced to 3.3V to supply power to the microcontroller.

6. Using LCD_TFT 1.8 inch screen, can display the collected data.

7. Counting is achieved through a transistor. When there is a radiation source, the radiation released by it passes through the Geiger tube and is ionized. At this time, a pulse signal is generated. At this time, the transistor is turned on, and the GPIO port of the microcontroller is configured as a pull-up input. When the transistor is turned on, the GPIO port is low, and an interrupt is entered to achieve a count.

8. Conversion of values, by configuring a timer to achieve timing of 1S, that is, the number of GPIO interrupts read every 1S, and judging whether the timer flag changes in the main loop to achieve reading data every 1S, and converting it into the corresponding radiation value, so that the method of judging the flag can avoid the blocking of the program caused by executing too many functions in the timer interrupt.

9. The frequency of the buzzer alarm sound varies with the change of the radiation value. I use the direct hard code part of the code, which is divided into multiple levels, each level corresponding to a different frequency. The change of frequency is achieved through delay. However, most traditional buzzer calls use the delay function, which will block the normal operation of the program. Therefore, the method I adopt is to configure a 1MS timer to implement delay in the timer, that is, to judge the given time length, and then use the if statement in the interrupt to determine whether the time has arrived. The content of this part is rather convoluted and needs to be read several times.

10. The refresh of the screen is in the form of flag bits, that is, the multiple levels mentioned in point 9. The flag bits corresponding to different levels are different, so as to determine whether the background color of the screen needs to be refreshed.

This part of the code is the task to be performed in the interrupt of the 1MS timer, on_time and off_time is the time of the buzzer ringing and off, for example, set the on_time to 100, that is, the buzzer rings 100ms,

last_on_time and last_off_time is to save the last set of time, so that the use of the buzzer can be repeated, or it is set every time the value of the buzzer will ring.

This part of the code is the core of the entire program. By judging the value of FLAG, it is determined whether the 1S timing ends, and then the value is converted.

At the same time, color_flag is used to determine whether the numerical background needs to be changed. At the same time, the judgment in the case is to avoid constantly refreshing the background, because constantly refreshing the background will cause the screen to flicker.

This part is the design of the UI interface.

If there is a chance in the future, battery voltage detection will be added, and the circuit will be optimized to make its size smaller. However, due to the high price of Geiger tubes, it may be shelved. Interested friends can follow.

Pay attention to safety during welding

At the end of welding, adjust the 5V voltage regulator circuit first, adjust the voltage to 5V, and then adjust 400V.

When adjusting the 400V boost voltage, do not connect the Geiger tube to the circuit to avoid damaging the Geiger tube due to high voltage (one is not cheap, it hurts if it breaks).

When adjusting the voltage, a multimeter needs to be used to measure and adjust, and the range of the multimeter needs to be selected correctly

The multimeter needs to ensure that there is no error when measuring high voltage. Personally, I have encountered this situation before when measuring low voltage accurately but high voltage inaccurately.

All circuits in this project have been tested by me and can be ordered directly.

Since the inductor used in the 5V to 400V circuit is now expensive on Taobao, the corresponding value of the I-shaped inductor can also be used instead.

Demo video

[Open source!! There are so many dangerous nuclear radiation detectors] https://www.bilibili.com/video/BV1iv411c7yZ?vd_source=8aba9b5c4b883e036e8f6340b7370c04

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