Signals to Photodiode

Hi,

I have a 555 circuit which generates a 30khz pulse. I use this to flash an IR led.

I am using a photodiode to pick up the IR pulses. Now the problem i have is that when i measure the frequency at the receiver end it is well below the 33khz.

Should this be happening. Could it be that the signal is too small for the multimeter to pick up a correct reading?

Thanks

You can't use a multimeter to read that.

Hi Nigel,

I used my multimeter's frequency function to read the frequency from the 555 output so i just assumed i could use it for reading the frequency on the "receiver" side as well.

It must then be that the signal is too small for a reliable reading?

AxelD said:

Hi Nigel,

I used my multimeter's frequency function to read the frequency from the 555 output so i just assumed i could use it for reading the frequency on the "receiver" side as well.

It must then be that the signal is too small for a reliable reading?

Click to expand...

From a photodiode FAR too small, use a scope or amplify it first.

Thank you.