I am going to make a prop for a haunted Hayride. It will be a Geiger counter with a simulated varible click sound.
A working Geiger counter with headphone output has been ordered.
We want to use it without any radiation and add a speaker so the sound can be heard without the head phones. Need to make the clicks go faster and slower just like the real thing.
I am thinking I can use a 555 timer and drive a speaker directly, but what timing arrangement do I need to get realistic click sounds?
We need to get the patron's off the wagon for a walk thru part of the hay ride.
Thay just went thru a toxic scene and we are going to tell them they are radio active and need to get off the wagon.
hi,
Yes, use a thermistor in place of timing resistor, the operator by placing/changing his finger pressure on the thermistor could vary the click rate.
But a Geiger counter's clicks ARE random. Unless you control the frequency so that the clicks are random but their average repetition rate can be increased and decreased they won't sound natural.
Explanation:
The outputs of two oscillators (U1a, U1b) with non-harmonically-related frequencies are ANDed (U1c,U1d) and the result differentiated (C4,R5) to give pseudo-random pulses for driving a speaker. The average frequency of both oscillators is dependent on the resistance of the LDR. In the light the average is low. In the dark it is higher. U1c and U1d are connected in parallel to share the current needed to drive the base of Q3.
But a Geiger counter's clicks ARE random. Unless you control the frequency so that the clicks are random but their average repetition rate can be increased and decreased they won't sound natural.
Yes ideally the clicks would be random, so I would need to increases the frequency of randomness to fatefully simulatet a Geiger counter.
But that may be to much to do with discret components in a weekend.
Explanation:
The outputs of two oscillators (U1a, U1b) with non-harmonically-related frequencies are ANDed (U1c,U1d) and the result differentiated (C4,R5) to give pseudo-random pulses for driving a speaker. The average frequency of both oscillators is dependent on the resistance of the LDR. In the light the average is low. In the dark it is higher. U1c and U1d are connected in parallel to share the current needed to drive the base of Q3.