-
Better robustness with external I2C PullUp resistors
06/26/2023 at 08:22 • 0 commentsFor components which have no onboard PullUps (e.g. the 16x2 LCD).
-
CPM calculation
04/18/2023 at 10:25 • 0 commentsAs for any purely statistical information (such as radioactivity) the question is what to do with cumulated data and in which manner present it to the user (on a display or other devices).
A straightforward way would be composing an arithmetic mean of extrapolated CPM values over a fixed time frame. For instance: 2s measurement, extrapolation, then take 5 extrapolated values and generate a mean value.
The most recent value replaces the oldest value (FIFO), what is basically a ringbuffer principle.
for (int i=0; i < ringbuffer_elements; i++) { sum += ringbuffer[i]; } mean = sum/ringbuffer_elements;
-
Battery indication
04/10/2023 at 12:08 • 0 commentsSimple battery indication with a voltage divider (5MOhm and 2.2MOhm), using Pico's ADC2. Shows for a few seconds whether battery is nearly full, half empty or nearly empty (only applicable for alkaline batteries with their characteristic discharge curve).
-
New PCB revision
04/05/2023 at 13:43 • 0 commentsNew PCB revision with some improvements.
-
HV measurement
11/12/2022 at 13:34 • 2 commentsSimple HV measure arrangement: consisting of four 82V Zener diodes, one 10 MOhm and one 2.2 MOhm resistor (series connection). These are parallel to the tube Anode and GND.
The Voltmeter is parallel to the 2.2 MOhm resistor.
On the picture you see a voltage of some 11V, what means the HV amounts in this case to:
HVtube = 11 + (11/2.2)*10 + 4*82 = 390V
(actually it is slightly higher since the Voltmeter has an internal resistance in the 10 MOhm range what affects the measured value)
Varying the PWM parameters in the SW would lead to higher and lower voltages, respectively.
The assembly described here could be the basis for a control loop design.