Wireless infrared headphones

I recently designed and built myself a pair of wireless infrared headphones. The project is documented on my website for anyone interested. Feel free to learn from the design and to send me questions.

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Cheers, Chris

Reply to
Apparatus
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Yes, I did well. This was for an introductory class.

The forward voltage did not vary all that much since it is set by the current through V_cc / (R_9 + R_10). However, I have allowed ample room for variance, taking into account the 50% duty cycle.

You are right. Should be as I stated above. Thank you for bringing the error to my attention.

The supply is quite stable, but yes I see your point. Noise could potentially be a problem in a particularly noisy environment.

Yes, R10 can be omitted, and R9 doubled to have a near equivalent effect.

Cheers, Chris

Reply to
Apparatus

There are a few design flaws in your work, did you really pass that class? Worst is the transmitter stage The current through the LEDs is only determined by their forward voltage it can vary a lot and will degrade performance since the max. permissable current is surpassed. Your calculation "current sourcing" is completely wrong. The LEDs are in the collector line and do not contribute to the Vbe calculation. The transmitter will have big noise problems, as you amplify any ripple on the supply voltage through your bias resistors, some of which can be omitted...

--
ciao Ban
Bordighera, Italy
Reply to
Ban

Thank you John. I appreciate the support. Hopefully the improvements will come with time.

Ah, the PDF contained an old version of the schematic. Should be fixed now. Thanks for bringing this to my attention.

Cheers, Chris

Reply to
Apparatus

I think you did quite allright. Of course there are improvements possible, but hey, only 10 weeks for a clean working prototype with pcb etc and a paper is not bad at all. One small point though, your paper references several components that I could not find in the schematic drawing: D8, D9, C17, C18, C24, R30 and there maybe others.

-- John

Reply to
John Smith

Haven't had a chance to read it yet - just scanned through. But it was darn nice of you to post it! Thanks!

Ed

Reply to
ehsjr

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