Frequency of a strobe light

[sfink06]

Anyone got any ideas for a circuit that can detect the frequency (# of flashes/second) of a strobe light? I have considered interfacing a photo-resistor circuit with a TC9400 chip, and reading output voltage with an ADC. However, I am not sure if DC offset of the wave coming off the photo-resistor chip will cause a problem, or how to get rid of it.

 

[Blueteeth]

You can easily 'get rid' of that DC off-set using a capacitor As long as you pick a value which is large enough for the lowest frequency you wish to detect as it will form a high pass filter. That said, IU'm sure the datasheet gives adequate information on the specs of the waveform the chip needs for proper operation.

Perhaps if you had explained what the TC9400 did (F/V converter), you may have recieved a quicker response, as I imagine many, like me, had to google it.

A frequency to voltage converter would do, but...if you're reading its output voltage with an ADC, one assumes you are savy with microcontrollers, or at least digital electronics. In which case, why don't you just measure the period of the output of the phototransistor directly? As few strobes are that quick (<1kHz), even a slow microcontroller could easily mesure the time between rising edges, then average them to get the mean flash frequency. Using an F/V converter would require you to calibrate it, since you're not doing it directly, the voltage you measure on it would depend on the chip in question. At least doing it directly would require only a few parts,