Nigel Goodwin said:
folarinv said:
You probably need to modulate the IR beam with an oscillator, and use a 3-pin IR receiver module, like used for TV remotes.
Once, I tried to interface a 3-pin IR receiver module with a 555 monostable for a similar circuit as posted above but it didn't work out. The problems were:
1) DC voltage is always present on the output of the IR receiver wether its receiving signal or not. Ideal case would have been for the output to go high when receiving and the voltage should disapear when not receiving.
They work the opposite way, they are HIGH normally, and go LOW when they receive 38KHz modulated IR. If you need it the other way, just add a simple transistor inverter.
I'll describe a test I carried out. I connected my 3-pin IR receiver (sharp)to 9V supply through a 470ohms resistor and 47uf bypass cap. Then I used a LED to monitor the output and also a digital multimeter. when not receiving, my LED remain ON and steady. My DMM read 7V. When it starts to receive, theLED starts to blink fast and the DMM still read about 6.7V, DC
2)
Because it was receiving modulated IR, the output was also modulated and therefore difficult to interface with my counter circuit.
Don't use a coded remote control for it, just use a plain 38KHz signal, it should work fine then!.