IR Audio Receiver

[kpraytor]

Hello everyone!

I am trying to make a simple go/ no go tester to determine if a remote control is outputting an IR signal. There is no need to clean up the signal or do anything else with it; I just need to know if the remote control is putting out any kind of IR.

I have attached the first design I had. This appeared to function correctly but the signal was not strong enough to make a very audible note, aka you had to hold the speaker up to your ear to here the noise being produced.

Unfortunately, I crossed some wires while testing it and fried the only speaker I had. Now, I am forced to go with a Piezo transducer to output an audio signal. It says on the packaging that it requires a driver circuit (?). I am new to the whole electronics thing and would like some advice concerning how to approach this driver circuit.

Thanks for all your help and I look forward to the responses!

Original_Circuit.pdf

[audioguru]

All transistors in your circuit are emitter-followers that have no voltage gain. Then the signal level is extremely weak. You need an amplifier circuit.
The piezo transducer is a capacitor that does not conduct DC so a load resistor is needed for the transistors. One transistor is not needed.

[Hero999]

There is nothing wrong with using emitter followers since current gain is required, not voltage gain.

The circuit won't work anyway because IR remote controls flash the LED at an ultrasonic frequency so you won't be able to hear it.

I would recommend using an LED to indicate the output, a tone decoder such as the NE567 or CD4046 might also be a good idea to block DC and mains frequency light sources.