The high voltage of 3000V to 5000V cannot be measured by high impedance, the special measurement circuit is needed.
Vpp voltage vs. operation voltage to GM tube
| Vpp voltage[V] | A/D | Operation voltage X[V] |
| 5 | 1.38/282 | 2256 |
| 6 | 1.67/343 | 2744 |
| 7 | 1.98/405 | 3240 |
| 8 | 2.29/468 | 3744 |
| 9 | 2.58/529 | 4232 |
| 10 | 2.84/581 | 4648 |
| 11 | 3.09/633 | 5064 |
It is changing linearly.
The analog voltage A and the operation voltage X can be drawn from the following expression of relations.
- Expression of relations with analog A and digital D(10bit resolutionA5V reference)
A[V]D / 1024 x 5 - Expression of relations with operation voltage V and analog voltage A(Voltage separation of resistance and 10 times of Cockcroft Walton)
X[V]alpha x A x 10M / 75K x 10, alpha is a coefficient by the waveform.
X[V]alpha x6.5 xD
If digital value D is known, the operation voltage X is known.
In order to simplify the digital calculation by PIC, it is referred to as X[V] =8xD. If it is 8 times, only shift operation is required.
75K has counted backward as divided resistance.(To be set to alpha x 6.5 = 8).
Although there are some errors (several 10 V), it is used enough.
In addition, the resolution of the above-mentioned thing to operation voltage is 8V.