ir emitter 38khz

Posted on Feb 5, 2014

I`ve built a 555 based oscillator to drive ir led at 38khz. I`ve got the circuit wired up and I`ve used my meter on the duty setting to read that it is indeed generated a 38khz signal. I`ve also wired up a modulated IR receiver, the one from radio shack set to 38khz. I`ve verified it`s working by pointing my TV remote at it. I`ve hooked up a red l

ir emitter 38khz
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ed to the output pin of the receiver and it lights up and flashes when I do this. The red led lights up occasionally especially if I move the receiver back and forth horzontally. I`ve checked for loose wires [this is all on a couple of bread boards], the led always lights up when I blast it with my remote. Oh I`m using a 5v source from a wall wart [the radioshack one that you can select the output voltage for] connected to a 7805 with a couple of capacitors. The power source circuit i bought and soldered together, it fits standard breadboards [solar-robotics] so hopefully its okay. One thing I did notice is on the timing capacitor, if I short the two pins of the capacitor with my finger, the receiving led lights up as if its working fora second or two then goes out. This works if I repeat the process touching the capacitor. I`m at work and don`t have the IR receiver circuit handy but I`ll post it when I get home. I don`t recal if I`m connecting the red led to ground or to +5V. The IR receiver itself is directly connected to ground and the +5V rails. I have a 1k resistor connected from the output pin to a regular red LED to indicat the presence of a signal. Do all modulated IR receivers have a auto gain mechanism I`ve seen so many of these little pulsed IR led circuits for simple obstacle avoidance that I`m beginning to wonder if I`ve missed something totally or my receiver just isn`t designed for my intended purpose. The...

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