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I'm trying to build a custom wireless doorbell, similar to those you can buy everywhere (example). I just need to emit a single signal and receive it elsewhere, to make a buzzer sound.

I've already got all the components except the RF device needed for communication. My requirements are: ~30 mts. distance, maybe passing through one indoor wall and not to be too expensive (you can buy one of those complete doorbells for less than $20). Ideally, I would trigger this module using a microcontroller operating at 3.3 or 5 volts, and as I'd hand assemble this, SMT components should be avoided.

Any advice?

Thanks

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    \$\begingroup\$ You'd be better off with a KeeLoq encoder/decoder IC pairing (or an equivalent) rather than using a microcontroller. The transmission question still stands, though. \$\endgroup\$ – CharlieHanson Dec 9 '15 at 0:40
  • \$\begingroup\$ @CharlieHanson: thanks for your suggestion, I never heard about those code hopping encoder/decoders, but I'll take it into account. \$\endgroup\$ – grieih Dec 9 '15 at 22:33
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Search for something like "433Mhz ASK transmitter" Something like this or maybe this.

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Advice?

Do some research because, if you expect that applying power via the doorbell to a cheap transmitter is going to produce a definitive signal at the output of the receiver you are going to be sadly mistaken.

The output from the receiver is going to be digital noise while ever the button isn't pressed. When the button is pressed, that digital noise will momentarily change to a recognizable "flat line" then rapidly return to noise as the button is released.

Can your microprocessor skills handle the decoding of that whilst simultaneously discriminating against the guy down the street using his key fob to unlock his car doors.

Do some research. See also this answer I gave recently regarding cheap AM and FM receivers and the hoops you have to jump thru to get them to work as you might expect them to.

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  • \$\begingroup\$ Thanks for your answer, it's really appreciated. In no way I'm looking for a magical solution which would allow me to send and receive a signal just pressing a button. I know things like filtering and pairing need to be done, and I'm willing to. However, as I'm not an expert in this field, I asked for advice on appropriate devices which would let me get started working. \$\endgroup\$ – grieih Dec 9 '15 at 22:30
  • \$\begingroup\$ Did you follow the link to the answer I gave the other day so that you can start to understand the bigger picture? \$\endgroup\$ – Andy aka Dec 9 '15 at 22:34
  • \$\begingroup\$ I did, of course. To be honest, while I expected to get my hands dirty, I hoped not to get that low-level. \$\endgroup\$ – grieih Dec 9 '15 at 23:14
  • \$\begingroup\$ Yes a lot of us have been there and learnt the hard way. It wouldn't be so hard if the suppliers of this kit gave you one fraction of a clue in their normally crappy data sheets. I'm still scarred by the experience and that was back in 1992 when they first started emerging. \$\endgroup\$ – Andy aka Dec 9 '15 at 23:21

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