The cheapest Wireless RC i've found

[ikalogic]

hi,
you all sure know about the ready made RF remote control modules like TX431 and the RX431 etc etc.. well i couldn't found any in my country, and it is very expensive for me....

so i bouhgt the cheapest wireless mic i've found, actually ~5$, along with its receiver.. and i figured out that i could turn it into a multi channel RC...

i thought about using 556 tone decoder, which i never ever used before..
I also thought about the pic 16F84A, which i did use a lot...
or maybe a simple mux demux Process....

any hints?? or is that possible anyway?

nb: if i can send a clear signal from a pic to a pic using that mic, my problem is solved, (the multi channel part is really not a problem..)

thx

 

[ikalogic]

won't anybody give me a litle hint please??!

 

[kinjalgp]

You can use analog FM transmitter and receiver pair with some modifications for sending digital data.

 

[ikalogic]

okay thx but what modification i have to do to send data pulses??

 

[kinjalgp]

If your FM transmitter has pre-amplifier stage, you need to bypass it since digital signal won't require amplification. 0-5V amplitude is sufficiently high to be modulated directly. Buffer it if necessary. In some cases you may also need to attenuate the signal using voltage divider if the signal is causing carrier deviation of more than 75kHz.

At the receiver end, you need to check if signal is crossing the logic boundry well. If not you need to amplify it and also use a clipper circuit so that the signal does not overshoot the 5V limit nor it should go below 0V.

This will actually turn analog FM Tx-Rx pair to FSK Tx-Rx pair.

 

[ikalogic]

ok , thx, but i was thinking, isn't there a way to send a frequency very simply though A and then pick it up through B ? i mean isn't there a respective change in output B for any change in voltage at input A ??

thx again kinjalgp, and i am sure what you are proposing is the most professional solution but i think it is too complicated for me... specialy i am very bad when it comes to reverse engineering!

 

[ikalogic]

here is another way of asking the question:

How can i simulate mic input without sound ?? (suposing i cut the 2 wires going to the mic?)

 

[kinjalgp]

here is another way of asking the question:

How can i simulate mic input without sound ?? (suposing i cut the 2 wires going to the mic?)

Use signal generator instead of MIC with its output set to 20mV(p-p) @ 1kHz.

Or even if you cut the MIC wires and don't apply any input to the transmitter, you'll still receive "silence" (no hissing sound) at the receiver. That is indication of un-modulated carrier being received.