phil555ip
Feb 16, 2004, 10:38 AM
Hello.
I have a few basic ideas about how to produce an IR control system for my degree project and would very much appreciate some feedback about them.
Tx: Use the encoder output from an existing radio control unit. Modulate an IR LED source with it. IR LEDs need to be pulsed usually somewhere between 30 and 50 KHz. Vishay TSUS540 is chosen: build suitable oscillator, AND this signal with o/p of encoder, buffer/amplify and connect to IR LED(s).
I could of course build a Tx from scratch; using 4017 decade counter with a 1ms clock input. O/ps connected through RC networks with control stick pots varying the RC time constant and hence length of pulse o/p, OR all the used o/ps together, AND with 36Khz sig, amp/buffer, radiate sig with IR LED.
Rx: Vishay TSOP1736 (36KHz Rx). Has internal automatic gain control (AGC) ,demodulator and preamp. Connect to clock i/p of 4017 decade counter with RC network to effect a reset i/p (i.e. detect sync pulse - a gap in the pulses). Connect o/p of counter direct to servos.
Another, slightly pointless, Tx design: Use binary switch for channel controls. Convert this to thermometer code i.e:
000 0000000
001 0000001
010 0000011
011 0000111
100 0001111
101 0011111
110 0111111
111 1111111
Use shift register to convert from parallel to serial code. This is effectively a PWM signal. Mux with other channels. Send to IR LED. This would be suitable for coil actuator control.
Rx similar to above.
I suppose you could use a 555 timer and alter the length of its pulses and multiplex with other channels, but then the 4017 way is simpler.
Could use a pic at Rx, but why bother? That would also involve learning how to program a pic, which doesn't appeal when there's so much other work to do...
I have a few basic ideas about how to produce an IR control system for my degree project and would very much appreciate some feedback about them.
Tx: Use the encoder output from an existing radio control unit. Modulate an IR LED source with it. IR LEDs need to be pulsed usually somewhere between 30 and 50 KHz. Vishay TSUS540 is chosen: build suitable oscillator, AND this signal with o/p of encoder, buffer/amplify and connect to IR LED(s).
I could of course build a Tx from scratch; using 4017 decade counter with a 1ms clock input. O/ps connected through RC networks with control stick pots varying the RC time constant and hence length of pulse o/p, OR all the used o/ps together, AND with 36Khz sig, amp/buffer, radiate sig with IR LED.
Rx: Vishay TSOP1736 (36KHz Rx). Has internal automatic gain control (AGC) ,demodulator and preamp. Connect to clock i/p of 4017 decade counter with RC network to effect a reset i/p (i.e. detect sync pulse - a gap in the pulses). Connect o/p of counter direct to servos.
Another, slightly pointless, Tx design: Use binary switch for channel controls. Convert this to thermometer code i.e:
000 0000000
001 0000001
010 0000011
011 0000111
100 0001111
101 0011111
110 0111111
111 1111111
Use shift register to convert from parallel to serial code. This is effectively a PWM signal. Mux with other channels. Send to IR LED. This would be suitable for coil actuator control.
Rx similar to above.
I suppose you could use a 555 timer and alter the length of its pulses and multiplex with other channels, but then the 4017 way is simpler.
Could use a pic at Rx, but why bother? That would also involve learning how to program a pic, which doesn't appeal when there's so much other work to do...