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IR Remote Control

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I was trying to find a circuit for RF remote control, but i give up(to hard to make modules by myself). it doesn't matter. Now if you can help me about my project. I want to build a IR remote control i think its better with TSOP modules (receiver & transmitter that include encoder &decoder) with a few commands (NOT JUST ONE!!!) much more commands is better, but i dont need above 10. I cant buy allready made encoders and decoders such as Holtek 12E&12D , i have to made them from (example:4017) some easy available ICs. Any circuit and advice about this subject will be helpfull.


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I think that is a little difficult for you to produce the RF circuit.
Even if you have the design schematic,that is not easy to adjust the Frequency if you don't have the specified equipments.
And you can buy the RF receive and Transmit module for you to use.
That is very easy .
Sometimes ,they use the Fixed Encoder and Decoder IC,such as the PT2262/PT2272;
And also sometimes,use the Rolling code controller and decoder,such as HC301,and use the software to act as the Decoder.
That is very easy for you to use.

Extract the software Code from the Programed MCU

Wafer Microelectronics Co.,Ltd
[email protected]

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Allow me to demonstrate the difficulty of making and interpreting commands without encoders/decoders. 

1. 555 Timer1 35KHZ carrier generator fed into input of an AND gate.
2. 4-bit Parallel to Serial shift register with command loaded on parallel inputs.  This functions as a Binary encoder.  Either a hardwired parallel data command per individual shift register, or 4-bit toggleswitch and just 1 shift register.  4-bit toggle to 1 register means you must toggle the switch manually each time a new command is desired.  555 Timer2 Baud Rate Generator is needed to drive the clock input of the shift register(s). 
3. To transmit, a TX button enables the clock for Timer2 and enables the shift register to send data on its serial out pin Ser-Out.  Ser-Out and Timer1 is fed into the AND gate and the gates output creates the needed modulated carrier for the IR receiver.  Modulated carrier is fed to an IR-LED.

1. 35KHZ IR-Module does not "decode" but only "filters" the carrier.
2. The IR-Module's serial output Ser-In now needs to be compared to some hardwired parallel data.
3. A Serial to Parallel shift register is driven from a 555 Timer3 Baud Rate Generator and triggered on Ser-In's first transition from idle.  Add J-K flip-flop to this.
4. The received Serial to Parallel data is loaded into a 4-bit Magnitude comparator.  This device compares its parallel input with hardwired parallel reference data.  If the 2 nibbles match, its A = B output is set, else A < B is set, or A > B is set.  1 Magnitude comparator for each command.

Most of the above is what USARTs do.  Encoder/Decoders use their own usarts, magnitude comparators, and carrier generators.  All in one package as opposed to 5+ discrete ICs.

Here is an analog method.  Some how you either manually press a 35KHZ carrier signal into an LED or use logic to send out a prefixed number if button presses.  Well, the IR-Module's ouput Ser-In is fed to a buffer.  The buffer charges a capacitor through a resistor.  The priciple is to charge the capacitor to different voltage levels by sending 1, 2, to X number of pulses from the Transmitter.  The capacitor voltage is fed to a bank of comparators.  Lets say 1 received pulse makes Vcap = 1v, 2 pulsed for Vcap 2v, and X pulsed for Vcap = Xv.  To interpret the pulse commands, each comparator connected to Vcap has its Vreference set to 1v, 2v, Xv.  The problem is that 3 pulses will turn on 3 comparators, so you must make all the comparators into Window comparators.  1 Window comparator is composed of 2 comparators whos inputs or tied and Vref(s) levels are near each other.  If Vin is too high the comparator stays off, and if Vin is too low the comparator also remains off.  Ok, now how do you discharge the Vcap in order to receive another command?  Add another timer, a Delayed Timer, that is triggered from either Ser-In or whatever.  Once the timer expires it discharges Vcap. to ground level.

When you said "easily available", why is an encoder/decoder not available?  May not be at local shop that I can understand.  But it may be mailed ordered.  I mean, you might have to mail order parts regardless how the project is done.

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The encoder circuit you found will sequence through one fixed and 6 adjustable frequencies, over and over. You can make it play a little tune. I don't know how it could be used for IR remote control. It could amplitude-modulate the IR beam with a transistor, then an IR receiver would play its tune. ;D

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i build those circuits (BUT I HAVE SHORT WIRED O/P AT DECODER AND Rx AT ENCODERS) but when i press any channel on trans. nothing happen's at receiver. It looks like cracked circuit.

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Did you connect the output of the encoder to the input of the decoder?
Did you use a 10nF coupling capacitor and join the points marked "X" with a 1M resistor in the decoder like Harry says to do in his article?

but when i press any channel on trans. nothing happen's at receiver.

The circuits do not have anything to press. They are designed for model radio control and sequence each pot's position a single time, then a pause. The decoder outputs each channel's pot position as a variable width pulse that a servo's electronics uses to move its position. 


Channel 0 is for the pause. The active channels have a pot for them to control a servo. ;D
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i replace those pot. with a tasters (can it work on that way)

What is a taster?
Each pot's resistance changes the pulse width of the oscillator for their channel. The decoder's channel outputs feed servos that adjust their position according to the pot's resistance.

That high value res. and 10n cap. ;should i conect them series between marks X or parallel between same?

The resistor connects between the points marked "X" to DC bias the input. The capacitor is in series between the encoder's output and the decoder's input and the resistor connected to it to block DC from the encoder's output. ;D
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