I have a 2xAA battery operated system that generates 500V for geiger counter. However for being 3V driven system the audio click sound for the system is very low. Mine is a basic transistor based driven system using a 3V passive buzzer. Can anyone please suggest how to get loud clicks in a 3V driven system ?
OK, if I understood you right, you want to connect a passive unpolarized buzzer to the “pulse output” of your circuit diagram, correct?
First, you need to test if the buzzer is loud enough if you just feed it with the 2 batteries power (3 volts).
If it is, put that buzzer instead of R3 and you are good to go.
If not, you’ll need a second transistor stage that inverts the “pulse output” via a 10k resistor and an additional NPN transistor. Connect the buzzer between the collectors of the two transistors. That will almost double the voltage across the buzzer.
I do not really like that HV generation circuit, since it produces unregulated HV. That will lead to varying sensitivity and spurious clicks.
Do you have an oscillscope to take measurements?