Peter's electronic projects

Infrared circuits for remote control


Infrared remote controls are using a 32-56 kHz modulated square wave for communication. These circuits are used to transmit a 1-4 kHz digital signal (OOK modulation) through infra light (this is the maximum attainable speed, 1000-4000 bits per sec). The transmitter oscillator runs with adjustable frequency in the 32-56kHz range, and is being turned ON/OFF with the modulating signal, a TTL voltage on the MOD input. On the receiver side a photodiode takes up the signal. The integrated circuit inside the chip is sensitive only around a specified frequency in the 32-56 kHz range. The output is the demodulated digital input (but usually inverted), just what we used to drive the transmitter. When the carrier is present, this output is usually low. When no carrier is detected, the output is usually high.

Stefan Ovidiu writes that if you'd need a low power device, replace the NE555 IC with an ICM7555 (the CMOS equivalent of 555) or use a quad NAND CD4011 to build a gated oscillator.


Q: I need 2 IR receivers & transmitters that don't affect each other (for example a remote control for a PANASONIC TV & a SONY TV) and work separately.

A: Please check my codec page @ You can use the 555 transmitter and the IC receivers with them. If you don't have the expertise in PIC programming to modify the code to suit your needs, you can consider the MC145026-8 IC-s. Check the datasheets and you can build transmitters & receivers with unique ID-s, so you can match them to each other.


Here is a sample list of receiver chips.

device manufacturer pinout notes
GP1U52X Sharp 1=OUT
2=VCC (+5VDC)
38 kHz
IS1U60L Sharp 1=VOUT
3=VCC (+5VDC)
60 kHz
output is inverted (LOW when carrier present)
TSOP17xx Vishay 1=GND
2=VCC (+5VDC)
30, 33, 36, 36.7, 38, 40, 56 kHz
output is inverted (LOW when carrier present)
TSOP18xx Vishay 1=OUT
3=VCC (+5VDC)
30, 33, 36, 36.7, 38, 40, 56 kHz
output is inverted (LOW when carrier present)

For a remote control application of these circuits, please check my encoder/decoder circuit.

schematic diagram


name value
R1 1k
R2 15-22k
use a 15k resistor series with a 10k potmeter to adjust frequency in the 32-40kHz range
R3 15 @5VDC, 200 mA peak
35 @9VDC, 200 mA peak
50 @12VDC, 200 mA peak
C1 1n
C2 47n

an older IR receiver design of mine is available, but it is only for detecting, not decoding a modulated IR signal.