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Infrared hands free for cell phone

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neazoi

neazoi

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Hello,
I would like to know if there are infrared hands free products for cellphones out there, or if there are any schematics instead of starting to design one by myself?

My goal is to build something simple that would work on a button cell and will fit in an ear plug. Something like these hearing aid ear pieces. This will communicate with a transceiver plugged on the hands free audio in/out of the phone.
 
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Infrared needs direct line of sight to communicate. I don't think there are any infrared hands free devices because it wouldn't be easy to use. You have to hold your phone near to your head and pointing your ear.. :-?
 

Genovator said:
Infrared needs direct line of sight to communicate. I don't think there are any infrared hands free devices because it wouldn't be easy to use. You have to hold your phone near to your head and pointing your ear.. :-?
Click to expand...

Yes I know how infrared works. Also I know these infrared "hi-fi" headphones work. The purpose is to build something small, totally healthy (no-RF) and wireless.
People do not use cabled hands-free because they hate cabling when hendheld.
 

My hearing aids communicate with each other, with the remote control and with the auxiliary input with low power Bluetooth radio signals. Then the tiny single button battery cell in each one lasts for one week.
If you use IR then it must compete with sunlight and artificial light that produce IR so its power must be fairly high and you might need a wagon to carry a big and heavy battery.

Another way my hearing aids use low power is that they have digital class-D amplifiers, not linear.

Thanks for reminding me. My calendar has my sticker that I changed my hearing aids batteries one week ago. Today they will let me know ("Beep beep- Low Baddery") when the batteries have half an hour of life remaining but I better change the batteries before I go out today.
 

Audioguru said:
My hearing aids communicate with each other, with the remote control and with the auxiliary input with low power Bluetooth radio signals. Then the tiny single button battery cell in each one lasts for one week.
If you use IR then it must compete with sunlight and artificial light that produce IR so its power must be fairly high and you might need a wagon to carry a big and heavy battery.

Another way my hearing aids use low power is that they have digital class-D amplifiers, not linear.

Thanks for reminding me. My calendar has my sticker that I changed my hearing aids batteries one week ago. Today they will let me know ("Beep beep- Low Baddery") when the batteries have half an hour of life remaining but I better change the batteries before I go out today.
Click to expand...

I am not so sure if infrared would be that power hungry.
Apart from that I believe a single AAA cell could last for many hours of talking. But AAA cell is big in size. Well ok the MIC has to be closer to the mouth, like a blue tooth.
 

Infrared will have VERY STRONG interference from sunlight and electrical lights so the IR beam must be stronger than them.
Your circuit will transmit a linear signal that uses high power ALL THE TIME, it is not digital.

A microphone can have a very sensitive preamplifier so that it does not need to be close to the mouth, but then it will pickup more background noises.

My remote controlled toy helicopters use IR but not outdoors due to sunlight interference. Their digital transmissions are powered from AA battery cells.
My TV remote transmits high power digital pulses but for very short durations so its AA battery cells last a long time.
 

Audioguru said:
Infrared will have VERY STRONG interference from sunlight and electrical lights so the IR beam must be stronger than them.
Your circuit will transmit a linear signal that uses high power ALL THE TIME, it is not digital.

A microphone can have a very sensitive preamplifier so that it does not need to be close to the mouth, but then it will pickup more background noises.

My remote controlled toy helicopters use IR but not outdoors due to sunlight interference. Their digital transmissions are powered from AA battery cells.
My TV remote transmits high power digital pulses but for very short durations so its AA battery cells last a long time.
Click to expand...

Thanks for your interesting points.
I used to think AM modulation (light intensity) on the IR diode not to consume so much power. I will use 1.5mm IR diodes and 1.5mm IR diode sensors that have a black intransparent case (light filter?)

Yes you got a point, in direct sunlight it will have problems if it is AM modulated. Things migh be better if it is FM modulated but this would require an ultrasonic carrier and more complex circuit.
The simple AM modulated circuit might do the job quite ok provided that it is not going to be used in direct sunlight.

My problem is that I cannot find a suitable 1.5v audio amplifier so I might be switching to a higher voltage type.
Any suggestions?
 

An FM carrier blasts its average power ALL THE TIME and wastes lots of power making heat because it is linear. AM is interfered with by many things. The receiver will pickup noise in between words unless it has squelch. A digital system does not get hot because the output transistor is switching on (no voltage across it) and off (no current in it) and is turned on only when needed.

Digikey.com and other American electronic parts distributors have sections on their website where you can specify the minimum supply voltage and many other spec's for an amplifier IC then it gives you a list of them.
A "1.5V" battery voltage drops to 0.9V and lower as it is used. The IR LED needs about 1.2V plus more for the modulator.
 
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    neazoi

    neazoi

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Audioguru said:
An FM carrier blasts its average power ALL THE TIME and wastes lots of power making heat because it is linear. AM is interfered with by many things. The receiver will pickup noise in between words unless it has squelch. A digital system does not get hot because the output transistor is switching on (no voltage across it) and off (no current in it) and is turned on only when needed.

Digikey.com and other American electronic parts distributors have sections on their website where you can specify the minimum supply voltage and many other spec's for an amplifier IC then it gives you a list of them.
A "1.5V" battery voltage drops to 0.9V and lower as it is used. The IR LED needs about 1.2V plus more for the modulator.
Click to expand...

Interesting points thanks!
A digital system is not good because it uses a local clock, which is RF. I need a system that has no local oscillator and this can be accomplished only by audio amplifiers in conjunction with IR as far as I know. This is the pnly reason I stick to this system.
 

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