Simple IR audio link
Description.
Here is a simple IR audio link that can be used to transmit audio signals up to 4 meters. The signal to be transmitted is applied to the base of Q1 via resistor R4.The transistor Q1 drives the IR transmitting diodes D1 and D2.The audio input will be modulated to the IR signals transmitted.
The transmitted IR signals will be picked by the photo transistor Q2.The emitter voltage of the transistor Q2 will change according to the sound modulated to the IR signal. The transistors Q3 and Q4 amplifies this signal to drive the speaker or headphone.C1 and R3 forms a filter to avoid interference from stray IR signals.
Circuit diagram with Parts list.
Notes
The circuit can be assembled on a general purpose PCB.
Use 9V PP3 batteries for powering the transmitter and receiver.
The phototransistor Q2 can be any NPN phototransistor like PNZ154, PNA1605F, BPW77NA or BPW85.
An 8 Ohm speaker or a headphone can be used to hear the sound.
You may also like:
Hi kiran,
Leave the base terminal(do not connect it in the circuit)
I just made this and it works!
dear sir,
where should I connect the base of the Q2 photo-transistor?
thanks
Thank you.
Hi Meleja you can use these transistor for all the transistors (Q1,2, 3&4)
Hi, would these transistors work?
http://au.element14.com/fairchild-semiconductor/pn3643/bipolar-transistor-npn-30v/dp/1163522
Im thinking that i will need them because i can only find 100ma 1.5v ir leds.
Hi Meleja yes they are 1.5 volt 20mA IR LEDs(IR emitters)
thanx a lot sir !!!!!
u replyng so fast thats so great of u !!!!
Are D1 and D2 1.5 volt IR emitters?
Hi Aniket any one of the following can be used BPX43, BPW85, L14F1, BP103, BPW17, BPW20, BPW77, BPW78, BPV11,
sir they are not giving me any photo transistor if i asked they are asking for the number of transistor so plz tell me number of any npn silicon transistor which is generally available any where !!!!
dear sir,
thanks for speedy reply.your advice information always helpful to beginner like me.Sir do you know what technology is used in IR helicopters [small].If you know please reply me.
Hi Kiran to avoid line of sight problem,use RF transmitter and receivers to control your helicopter (normally the rc is supplied as part of equipment by the toy supplier and not available in the free market).
dear sir,
i wanted to apply this idea to make a transmitter and receiver for my micro rc helicopter which i have made.Can you please help, I think we have to slightly change the circuit.Can you please tell where and what to connect.
Thanx sir !!!
Hi Aniket any silicon NPN photo transistor could be used.
The above photo transistors are not available plz tell me other phototransistor which i can use
Thanks a lot! Dear seetharaman. Can you please send me more information regarding “home made photo-transistor” by mail me to: “vrndrsngh85@gmail.com” Your reply shall be hightly appreciated.
With Regards!
What audio input shud i use ? ? ?
should i usee general purpose mic or anythng else ? ? ?
Hi Virender if you have a old optical mouse from which you use. or you can prepare one by using a bc108 or 2N2221. by filing the edge of top portion of the transistor remove the top disc. clean internals with pure alcohol dry and then fix a small transparent plastic disc in the top hole with suitable adhesive. you photo transistor is ready.
Hi all, can anyone please let me know how to change Q2 in the receiver side. I could not find any NPN phototransistor like PNZ154, PNA1605F, BPW77NA or BPW85 in our area. Any reply shall be highly appreciated.
Plase mail me to :vrndrsngh85@gmail.com. Thanx in advance.
nice brooooooooooo.
Hi Rio the additional cost is not going to give any effect on the receiver.
what happens if i put 2 phototransistors?
Dear sir, can u plz. let me know how to replace Q2 phototransistor with IR LED. I mean I want to use IR LED by replacing phototransistor in IR Audio Link Circuit. It is possible? Any reply shall be highly appreciated. With thx.
how can i get the complete inverter circuit
Hi Rajesh D1 & D2 are IR diodes. You have to take care of anode and cathode. transmitter and receiver should see each other line of sight is important.
This circuit transmits mono signal only. For stereo encoder and decoders are required. The principle of operation is the communication through modulated IR signal. The audio source modulates the IR LEDs they transmit modulated IR beam. The IR transistor in the receiver receive the signal it is demodulated and amplified by Q3 and Q4. For stereo a simple way will be use two identical circuits for each channel. use polarizing glasses for each channel transmitter and receiver. Use vertical polarization for one channel and horizontal for the other.
Hai,
is this circuit transmitt mono signal or stereo signal? If it is mono how can i make this stereo. What is the input voltage of audio signal in transmitter? Can you tell me how is this circuit transmitt and receives audio signals? What is the principle of working of this circuit?
what a value of d1 &d2 in a ckt.it can work in any direction from trans to rece. i need urgent
Hello seetharaman, I want to use this circuits in some different purposes – like Remote ON/OFF LED bright Light circuit . I want to use TV Remote in this purposes . If I pressed one time in any button of TV Remote then LED will glow and again pressed remote button LED will be OFF . I want to make this circuit with photo transistor . Please don’t say to use CD4017 and Relay . Because I cann’t use it . Because I have a LED light which have 20 LED’s and 4V 0.5Ah Battery which casing too small to establishe Relay and IC there .
Please tell me how can I make such circuit with photo transistor ?
And about this circuit – It for mono only ! How can I make it for stereo ? I don’t understand why most designer design their audio circuit as mono !! What is the problem with designer to make stereo ?? I really don’t understand !!
Please reply …. I am waiting for your reply ……
Hi Mohin the output of this circuit, to be connected to a bistable such that its output will go high with one push and with second push it will go lo.
To make the above circuit suitable for stereo it will become a dual channel transmission, then you require an encoder to multiplex both the channel signals for sending and a decoder at the receiving end to convert into discrete channels. this will make the circuit complicated as there is no suitable IC available in the market for the same. we will try to develop a discrete circuit in the future.
Hello seetharaman, I want to use this circuits in some different purposes – like Remote ON/OFF LED bright Light circuit . I want to use TV Remote in this purposes . If I pressed one time in any button of TV Remote then LED will glow and again pressed remote button LED will be OFF . I want to make this circuit with photo transistor . Please don’t say to use CD4017 and Relay . Because I cann’t use it . Because I have a LED light which have 20 LED’s and 4V 0.5Ah Battery which casing too small to establishe Relay and IC there .
Please tell me how can I make such circuit with photo transistor ?
And about this circuit – It for mono only ! How can I make it for stereo ? I don’t understand why most designer design their audio circuit as mono !! What is the problem with designer to make stereo ?? I really don’t understand !!
Please reply …. I am waiting for your reply ……
Hi Musthafa Audio input is fed to IR transmitter and the sound is transmitted as modulated IR ray. This ray is sensed by the photo transistor Q2 and converted back to audio signal. the out put can be suitably amplified and listened. This is a cable less audio link.
what component used in audio in and audio out
hi
does this circut work, has it been tried and tested.
thanks Ian
Great site! I am loving it!! Will come back again – taking you feeds also, Thanks.
Hi i am wondering if anyone has got this circuit to work because when I tried it the two receiver transistor got a bit hot any the circuti did not work
Mike
I am very much interested in tracing circuits, though I do not build them. I like to see each and every circuit that I come across. I thank Mr.John for his circuits. Can I give some ideas, as expect any one in your group build them for me? kindly reply.
regards
v. Hari Hara Prasad
v.h.h.prasad@gmail.com
age 53, Male, India