Multi RF detector/emitter?

Hi! I have several "Light Sensor Timers" with remote controls.

I believe the remote is RF because they can "work through walls" at 80 ft. range.

Each timer is on a different RF "channel"

If I want to write a program to send on/off signals to each channel in a sequence, what do I use to determine the frequency channel of each individual sensor and what can I use to emit the RF signal from the Arduino?


To start, you will need to reverse engineer the circuit to determine what kind of control device is needed.

Example, BJT, MOSFET, Opto isolator, dry contact . . .

Assume you will be using the existing transmitter.

Well if they are RF, then a spectrum analyser is the normal tool.

Although a simple USB SDR receiver might be enough for an experienced RF person.

Decoding random RF signals from remotes is not at all easy.

And if they use rolling codes then cloning the remotes might not be practical.

How long do you want to spend learning all this stuff ?

Please post all the identifying information that you can find on the remote(s), or better, a link to where you purchased them. A photo of the label would help.

The chances are pretty good that they might use the Arduino-compatible RC-Switch protocol.

Hello and thanks for your replies.
It is called "smart electrician" mechanical 24 hr timer with remote pack
here is the link

The difference in the linked product and the one I have, which no longer seems to be commercially available, is that it also has a dawn/dusk sensor
As far as frequency, the paperwork says that the device complies with "Part 15 of the FCC Rules"

That almost certainly uses the RC-Switch protocol, which is very simple. But you need to know the operating frequency, likely to be 315 or 433 MHz. Look up the FCC ID on the nameplate to find out.

These simple, cheap TX/RX modules will work (available on line):

Thank you. This is interesting. Is there a possibility they are running on a range of frequencies between 315 and 433 MHz? I have 5 of them and they all have their own remote, and they each seem to operate on different frequencies. They are each labeled as "Channel A, B, C...etc."

The channels are probably digital identifiers, not "frequencies". Have you looked up the FCC ID yet?

I opened the remote and there is nothing printed on the disk as in the photo of the TX/RX

I was mistaken, My eyesight is failing. It appears to be 315. I

You will need 315 MHz Rx and TX modules, an Arduino and the RC-Switch Arduino library to decode and send signals.

Plenty of tutorials on line! One example: Decoding and Sending 433MHz RF Codes with Arduino and RC-Switch - DFRobot

The protocol is independent of the radio transmission frequency.

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Thanks for getting me on my way!

Glad to be of help.

Be aware that there are several minor timing variations of the RC-Switch protocol, and if yours in not already in the library code, it may be necessary to add it.

The only time I've used it was just such a situation, in which case this tutorial helped me to figure out what was going wrong: Reverse Engineer Wireless Temperature / Humidity / Rain Sensors — Part 1 « RAYSHOBBY.NET

Another thought regarding sensors....
these plugs have a "dusk/dawn" sensor feature that turns the relay ON when it is dark and OFF when it is light. Is there any way to reverse this control?

Probably, but that’s why we need a schematic.

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