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Topic: NRF24L01+ antenna connected to AC audio line (Read 973 times) previous topic - next topic


NRF's are wireless devices. They are designed to transmit RF.

If you don't want wireless then why are you even talking about using wireless transceivers?


Does this make sense?

I cannot have the nrf24's go through the air,

Why not that is what it is designed to do.
it must be through the guitar cable. (will have no interference if I turn and am between the two nrf24s,

If you want it to go through a cable then you have the wrong device your transmitter will not work like this at all. You need a modulation device some what like that used for communications through the mains.

not having a 4 inch antenna sticking out of my guitar

Why, that picture you posted showed it had a PCB antenna, why do ypu want another one?

So, my main question: will a very very low voltage AC signal hurt the nrf24s?

Yes it will.
I would assume not, since it is well below its operating voltage (even if its AC).

There are more ways of damaging an input than taking it over the supply voltage. A 1V signal is massive compared to the signal it is designed to amplify, it would not surprise me if it blew the front end.


Mike, thank you for answering my question.

Do you know of a better module than to use the NRF24 in this circuit?

I basically wanted a >1ghz fm communication line that wasn't going to cost me an arm and a leg, would work for a good distance(the farther the better), and would work over the guitar cable rather than through the air.
I was only thinking to use the NRF's because I have a few of them lying around, and they are really cheap in price, good distance, etc.

Food for thought.


I basically wanted a >1ghz fm communication line ............. and would work over the guitar cable rather than through the air.

Those requirements are mutually exclusive. A guitar cable can not carry a 1GHz signal. It is a shielded cable, and the capacitance of the cable will kill a 1GHz signal stone dead.

If you do want to do this trick then modulating the information at something like 500KHz is what you need to do. However I don't know of anything that does this sort of thing apart from the mains ( AC power or line depending on where you live ) controllers that turn stuff on and off by sending signals through the domestic wiring.


The issue with antenna size depends on the RF band used.  The issue with cross talk means choosing suitable correct
channels to avoid interference.  The issue with signal dropping out is why you want antenna diversity (2 or more
receiver antennas at difference positions/angles - which with the Nordic module means having more than one

An RF antenna is a tuned component - place it near some other metal and its efficiency can drop by large factors.
To be honest the PCB antennas on that module are not great - get a module which takes a plug-in antenna and use
a 1/4 wave whip (not very big at 2.4GHz)

There are ways of coupling an antenna to a wire to cause the signal to travel along the wire, but its really not going
to work here as the wire will re-radiate the signal within a few wavelengths anyway (if unshielded), or probably be
mainly absorbed (in a shielded audio cable which don't use suitable insulation for UHF) - and the coupling has to
be tuned for the RF carrier frequency for any efficiency.

Or the far simpler solution:  Add another wire to run alongside the audio cable and carry the data.  CAT5 perhaps?
[ I won't respond to messages, use the forum please ]

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