Infa-Red Remote Control

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I have received a number of emails requesting schematics for infa-red remotes. So here is one. This remote transmits a tone using an infa-red LED. This tone is decoded by the receiver. Since the receiver only switches when it "hears" the tone, there are no accidental activations.

Schematic For Transmitter

This is the schematic of the IR Transmitter

Schematic For Receiver

This is the schematic for the IR Receiver

Parts

Part	Total Qty.	Description	Substitutions
R1	1	22K 1/4W Resistor
R2	1	1 Meg 1/4W Resistor
R3	1	1K 1/4W Resistor
R4, R5	2	100K 1/4W Resistor
R6	1	50K Pot
C1, C2	2	0.01uF 16V Ceramic Disk Capacitor
C3	1	100pF 16V Ceramic Disk Capacitor
C4	1	0.047uF 16V Ceramic Disk Capacitor
C5	1	0.1uF 16V Ceramic Disk Capacitor
C6	1	3.3uF 16V Electrolytic Capacitor
C7	1	1.5uF 16V Electrolytic Capacitor
Q1	1	2N2222 NPN Silicon Transistor	2N3904
Q2	1	2N2907 PNP Silicon Transistor
Q3	1	NPN Phototransistor
D1	1	1N914 Silicon Diode
IC1	1	LM308 Op Amp IC
IC2	1	LM567 Tone Decoder
LED1	1	Infa-Red LED
RELAY	1	6 Volt Relay
S1	1	SPST Push Button Switch
B1	1	3 Volt Battery	Two 1.5V batteries in series
MISC	1	Board, Sockets For ICs, Knob For R6, Battery Holder
RELAY	1	6 Volt Relay

Notes

To adjust the circuit, hold down S1 while pointing LED1 at the receiver. Adjust R6 until you hear the relay click.

You can increase range by using a high output LED for LED1.

Bright light will stop the receiver from responding to the transmitter.

There is an error in the schematic. There shuold be a 1 megaohm resistor between pin 3 of IC1 and ground. This provides a 0 volt reference to bias the IC.

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Comments

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anonymous Infa-Red Remote Control Thursday, December 27, 2012 10:12:07 PM

How long is the range of IR transmitter can afford? Should I put the transmitter and receiver in a dark place? Thanks

anonymous Infa-Red Remote Control Tuesday, February 28, 2012 3:09:39 AM

oh........dont waste your time...its fake

anonymous Infa-Red Remote Control Friday, November 25, 2011 11:09:18 PM

Sine input & output to IC1 is capacitor coupled, there is no need for dual voltage supplies for the opamp. You can use single supply and ground, yes?

Andy Infa-Red Remote Control Wednesday, October 27, 2010 3:33:19 AM

A lot of people have questions about possible replacements. The 2N2907 PNP can possibly be replaced by a 2N3906 or BC327. The LM308, try substituting TL081CN. If better precision is required on R6, try using a trim-pot instead. For the IR LED and Phototransistor, try radioshack.com, they sell a matched set at http://www.radioshack.com/product/index.jsp?productId=2049723 for $3.49

darpan pathak Infa-Red Remote Control Friday, September 03, 2010 6:51:39 AM

in receiver circuit i think the connection between 1 and 8 is not right there will be a 5 in place of 8

fatha Infa-Red Remote Control Monday, July 12, 2010 8:02:22 AM

what kind of NPN PHOTOTRANSISTOR IS USED HERE? is there any substitution of LM308?

Lee, Manchester, England Infa-Red Remote Control Sunday, April 18, 2010 6:03:04 PM

I set up the circuit for a small project and it worked very well. In order to function correctly, the reveiver needs to calibrated so as the Centre Frequency of the Tone Decoder, matches the frequency of the output of Pin 6 of the Op Amp. this is acheived by adjusting the Potentiometer to the required resistance (2.275K according to my calculations). if its difficult to set the Potentiomter exactly use a decade counter instead. The Frequencies have to be matched because the Tone Decoder purposefully has the characteristic of a high rejection ratio of intruder IR signals, ie TV Remotes. Also it is advisable to choose an IR Emitting Diode and Phototransistor that are strongly compatible with each other to acheive the best response time. The de-coupling electrolytic capacitors external to the Tone Decoder do not have to be the exact values stated, but as close as possible. Enjoy!

saad Infa-Red Remote Control Wednesday, April 14, 2010 9:17:42 AM

at what frequency does the LED of transmitter circuit emit infrared rays ? can any one help please !!!!

RAVINDER PAL SINGH Infa-Red Remote Control Sunday, April 04, 2010 2:10:12 AM

what kind of NPN PHOTOTRANSISTOR IS USED HERE? what the type (number)of Infa-Red LED ? plz tell

anonymous Infa-Red Remote Control Friday, March 05, 2010 8:42:51 AM

This is great.

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anonymous	Infa-Red Remote Control	Thursday, December 27, 2012 10:12:07 PM
How long is the range of IR transmitter can afford? Should I put the transmitter and receiver in a dark place? Thanks
anonymous	Infa-Red Remote Control	Tuesday, February 28, 2012 3:09:39 AM
oh........dont waste your time...its fake
anonymous	Infa-Red Remote Control	Friday, November 25, 2011 11:09:18 PM
Sine input & output to IC1 is capacitor coupled, there is no need for dual voltage supplies for the opamp. You can use single supply and ground, yes?
Andy	Infa-Red Remote Control	Wednesday, October 27, 2010 3:33:19 AM
A lot of people have questions about possible replacements. The 2N2907 PNP can possibly be replaced by a 2N3906 or BC327. The LM308, try substituting TL081CN. If better precision is required on R6, try using a trim-pot instead. For the IR LED and Phototransistor, try radioshack.com, they sell a matched set at http://www.radioshack.com/product/index.jsp?productId=2049723 for $3.49
darpan pathak	Infa-Red Remote Control	Friday, September 03, 2010 6:51:39 AM
in receiver circuit i think the connection between 1 and 8 is not right there will be a 5 in place of 8
fatha	Infa-Red Remote Control	Monday, July 12, 2010 8:02:22 AM
what kind of NPN PHOTOTRANSISTOR IS USED HERE? is there any substitution of LM308?
Lee, Manchester, England	Infa-Red Remote Control	Sunday, April 18, 2010 6:03:04 PM
I set up the circuit for a small project and it worked very well. In order to function correctly, the reveiver needs to calibrated so as the Centre Frequency of the Tone Decoder, matches the frequency of the output of Pin 6 of the Op Amp. this is acheived by adjusting the Potentiometer to the required resistance (2.275K according to my calculations). if its difficult to set the Potentiomter exactly use a decade counter instead. The Frequencies have to be matched because the Tone Decoder purposefully has the characteristic of a high rejection ratio of intruder IR signals, ie TV Remotes. Also it is advisable to choose an IR Emitting Diode and Phototransistor that are strongly compatible with each other to acheive the best response time. The de-coupling electrolytic capacitors external to the Tone Decoder do not have to be the exact values stated, but as close as possible. Enjoy!
saad	Infa-Red Remote Control	Wednesday, April 14, 2010 9:17:42 AM
at what frequency does the LED of transmitter circuit emit infrared rays ? can any one help please !!!!
RAVINDER PAL SINGH	Infa-Red Remote Control	Sunday, April 04, 2010 2:10:12 AM
what kind of NPN PHOTOTRANSISTOR IS USED HERE? what the type (number)of Infa-Red LED ? plz tell
anonymous	Infa-Red Remote Control	Friday, March 05, 2010 8:42:51 AM
This is great.