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infrared cordless headphone

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nice_17

New Member
i need to know the audio transformer rating for infrared cordless headphone????????? pls can someone help me out??????:confused:
 

audioguru

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Most Helpful Member
Why would it use an audio transformer? Audio transformers have not been used in communication circuits for 60 years.

I think there is a site in India with an IR headphones circuit. It uses an audio transformer. The circuit does not work.

Please post your circuit.
 

nice_17

New Member
actually i dont have the circuit just now, but i got that circuit from electronics for you site, n if it is not correct then pls do sent me the proper circuit????????
pls help me out, it is quite necessary.:eek:
 

audioguru

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That is the Indian circuit that does not work:
1) The transistor is not biased so it rectifies the signal producing severe distortion.
2) The red LED abruptly limits the current which causes even more severe distortion.

I think the design of the IR receiver is just as bad.
 

nice_17

New Member
thanks but can u tell me what are the defects in receiver circuit and what should be done to get rid of these problems.
 

audioguru

Well-Known Member
Most Helpful Member
Why not use a modern little power amplifier IC like an LM386?
It has much less distortion and uses much less battery current than the horrible old circuit.
It has a push-pull output that is capacitor-coupled to the headphones so they don't have DC in them.
The LM386 can have a gain of 200 if a capacitor is added from pin 1 to pin 8.
 

nice_17

New Member
thanks, as i m a beginner so if i would get the circuit then it would become more easier for me to make it.
 

audioguru

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Hi Nice,
You need a modern audio amplifier like an LM386 then it has a 470uF output coupling capacitor.
Make the IR receiver like this:
 

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audioguru

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Hi Nice,
It is easy to use the LM386 audio amplifier IC to drive a power transistor that drives two IR LEDs in series with amplitude modulation. A 9V alkaline battery will become weak in about 10 hours.

What country are you in?
 

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audioguru

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India is on the other side of the world from me.
When I wake up in the morning it is very late at night in India but you are still awake.

Some TVs do not have an audio output. If yours does then try it.
Use an old cassette tape player.
Use a CD player or MP3 player to test your IR transmitter/receiver.
 

nice_17

New Member
hello sir,
i have all the components with me, and i fabricated them on the bread board but i am not able to understand the connection of headphone on the breadboard.pls help me?????
n someone suggested me to use a mic as input, would it be correct to use a microphone????????
 
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Mikebits

Well-Known Member
I have been used before. Did not like it, never use Mikes...:) Mic's maybe.

Wonder what jokes I set myself up for on this one...?
 
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