Modification for the "Master"

For a long time, I had an idea to make my own dosimeter, so to speak, with ladies and preference, until my dosimeter developed by Horizon, a Minsk company, was very dusty in the box.

The second picture in the search immediately found the scheme of this device. As in my opinion, the scheme is simplified so much that it is easier and nowhere to go, respectively, and it will work for a very long time.
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Everything works very simply, when you press the start button, all timers and counters are reset, then the voltage converter is started to power the sensitive element (in my model there was a SBM-20 wrapped in foil) and the device counts incoming pulses for 36 seconds. To start a new measurement, click again on the "Start" button.

Only this simplicity did not quite suit me, I wanted some convenience. For example, replace 4 tablet batteries with a battery, make USB recharging, add continuous counting mode, sound notification, increase the scale, make the display backlight and for some reason touch buttons.

I started upgrading, of course, from the most important ... from the touch button. And since it happened in a rush of creativity and inspiration, he did so quickly. In the bins of the motherland, there was a 74HC04 logic negative chip, a 4 mΩ resistor and a superglue. From the list of components it is clear that nothing good and beautiful was destined to happen. The microcircuit was stuck belly up and a resistor was soldered to the legs.





For the backlight, the display from the old LG was brutally torn to pieces. During the addition, I liked most of all that a piece of cardboard, already yellowed, was carefully laid by Soviet engineers under the display. The truth had to be at least carefully disposed of and replaced with a more light-conducting material. A backlight reed switch.



For the new heart of the device, I chose ATtiny13. MK is a small, rich choice of clocking frequency, and I just wanted to play around with such a beast. Although the scatter on the power supply at the Tinky is quite large (2.7 - 5.5V), the master transducer did not work with a voltage below 5 volts. So that happiness was for everyone and no one left offended, I installed a proven DC-DC converter NCP1400, and for charging a LTC4054 lithium battery. The role of the sound source is the usual piezo-dynamics connected via a transistor to the controller input. It doesn’t sound very loud, but it is very luminous and authentic.





Since the device initially consumed a meager current and wanted to continue this glorious tradition, the frequency of tinky underestimated to 128 kHz. With such clocking and “Power-Down” mode, the MC consumption will be microamps, which is fine with it.

I will not consider the program code any further, there is nothing extraordinary there: a micro-x-ray count for interruption, a buffer for 36 seconds, a watchdog for sound and healthy sleep, an ADC for checking the condition of the battery. The project for AVRstudio is in the archive with the DipTrace files.


Link to source

ZY With a battery, I was brutally inflated, the discharge-charge cycle showed a capacity of just over 200 mA.