IR receiver and transmitter

[Frozen-Mind]

Hello guys/girls

I am building a circuit that receive IR and transmit it

the source transmit 66Hz square wave with 0.5s on/off time interval

(Band Pass and PEak Detector)
I need to a band pass for the circuit that maintain only signals from 64-67Hz after the receiver. also i need to make peak detector to handle the gaps between the received square signal. But in order to find the capacitors and resistors for the band pass and peak detector do I have to use the time interval for the signal to be 0.5=5RC ??.
and is the way i connect them correct? do i need to connect the peak detector after the AnaloguetoDigital or before it? as in the diagram. ( see attachment ).

(Oscillator)

firstly, where do i have to connect the output of the Schmitt trigger to the oscillator circuit??.
in order to get 38kHz IR beam,
i used this equation to calculate the frequency

f = 1 / (Trise +Tfall) = 1/RC x 1/ ( ln (Vcc-VTL/Vcc/VTH) + ln(VTH/VTL) ).

How do i find the VTH and VTL to manage the values of RC to get the required frequency (38+- 3kHz)..
----

Vcc = 5v.

thanks in advance

 

[Frozen-Mind]

Is my english the reason for not understanding my post

 

[ericgibbs]

Is my english the reason for not understanding my post

hi FM,
From your description is the circuit an IR 'repeater' circuit, ie: receives a IR signal , modulates it and then retransmits it.??

 

[Frozen-Mind]

it basically receives IR (66Hz) and generates 38kHz IR and send it back to the source ( if that is called IR 'repeated circuit'. then yes it is . I am not that professional in electronics still second year engineer.

thx for the respond

 

[ericgibbs]

it basically receives IR (66Hz) and generates 38kHz IR and send it back to the source ( if that is called IR 'repeated circuit'. then yes it is . I am not that professional in electronics still second year engineer.

thx for the respond

hi,
The 74132 has two inputs, you only need one input for the oscillator feedback R4 and C4, you could use the other input pin for gating [ modulating] signal.

When the pin from the LM324 pin 7 is high, the oscillator will be enabled.

Take care to ensure that pin7 voltage is within the TTL specification for the 74132.

E.

 

[ericgibbs]

hi,
This simple circuit will give a clean synchronised pulse out.

Note: the Gate is Low for oscillator Enable.

 

[Frozen-Mind]

Hi Eric

so simply i connect the output from pin 7 (LM324) between the feedback R4 and C4. but what about the thresholds levels for this Nand gate, do i need to find them or the IC will do that for me? if so, i just need to calculate the R4 and C4 in order to get 38kHz. sorry for the trouble .

thanks a lot

 

[ericgibbs]

hi,
No trouble at all.

What is the supply voltage to the LM324 and the 132 IC.??

 

[Frozen-Mind]

5 voltage

 

[ericgibbs]

5 voltage

hi,
The datasheet for the LM324 shows that the maximum high output voltage is Vss -1.5V, so thats 5-1.5V = 3.5.

This should be high enough to enable the 74HC132 input, if not add a pull up resistor on the LM324 pin 7 to +5V, a 10K should be OK.

 

[Frozen-Mind]

i am so thankful to you man . I hope my circuit works. tomorrow i'll assemble it and see the results.