Uploaded December 2023 | Updated September 2026, 1 day ago
I made a device that measures the frame rate ("speed") of analogue film cameras. At the low frequencies these film cameras run it is not possible to use digital counters, because the measuring time for a three digit xx.x display would be 10 seconds (for 24.0 frames per second you woukd have to count to 240 within a gate time of 10 seconds). So this circuit works on the principle of integrating pulses of equal length by charging a capacitor. The voltage on this capacitor is then proportional to the frequency.
I made a device that measures the frame rate ("speed") of analogue film cameras. At the low frequencies these film cameras run it is not possible to use digital counters, because the measuring time for a three digit xx.x display would be 10 seconds (for 24.0 frames per second you woukd have to count to 240 within a gate time of 10 seconds). So this circuit works on the principle of integrating pulses of equal length by charging a capacitor. The voltage on this capacitor is then proportional to the frequency.
