RF remote module

Discussion in 'General Electronics Chat' started by kgstewar, Aug 20, 2013.

  1. kgstewar

    Thread Starter Member

    Apr 5, 2012
    151
    6
    Hi all,

    I have been playing around with some 433Mhz remote control modules that are commonly available on eBay. So far I've had good luck with the kinds that use mini mechanical relays, like this one. There are three outputs for each relay: a common, normally open, and normally closed. Easy.

    So now I have purchased this kind to play around with. Much smaller and I think it has solid state relays instead of mechanical relays. The problem I have is that I don't know how to connect to the relays. Each channel has only one pin, so not sure how to use this style. I tried using the ground for the common, but that didn't seem to work. I assume with only one pin it is normally open, but does anyone have any ideas what pin to use for the common? Of course the "instructions" are useless. I posted some photos of the module below.

    Thanks!

    Kevin

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  2. kinglouisvii

    New Member

    Dec 10, 2012
    2
    0
    My guess is those are just general purpose outputs, ie. on/off high/low signals. So you need an external relay.
     
  3. radiohead

    Active Member

    May 28, 2009
    474
    31
    Try experimenting with LEDs to see if you can get them to light. From there, you can use that signal to bias an external transistor to trip a relay.

    By the way, what are the markings on that chip?
     
  4. strantor

    AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    ebay description says "Please refer to the user manual for detailed operation"

    Did you get a user's manual with it? If so, can you scan & post it?
     
  5. kgstewar

    Thread Starter Member

    Apr 5, 2012
    151
    6
    Here is a link to the manual that came with the module.
     
  6. kgstewar

    Thread Starter Member

    Apr 5, 2012
    151
    6
    Good ideas about the outputs being just on or off and I will try the LED strategy and see if I can get anything to light up. The less-than-helpful manual makes it sound like the board has relays, but maybe that's not the case.

    THanks!

    Kevin
     
  7. kgstewar

    Thread Starter Member

    Apr 5, 2012
    151
    6
    The big chip has no markings at all. If this module is like my other modules, it's probably a microcontroller.

    Kevin
     
  8. kgstewar

    Thread Starter Member

    Apr 5, 2012
    151
    6
    Problem solved! The LED trick showed that the pins just go high and low. I now wonder how much current these pins can take...Thanks again for all the help.

    Kevin
     
  9. radiohead

    Active Member

    May 28, 2009
    474
    31
    if they can turn on an LED, they can bias a thyristor or a transistor to toggle on or off relays to switch higher current loads.
     
  10. kgstewar

    Thread Starter Member

    Apr 5, 2012
    151
    6
    Yes, good point. I actually only need these to trigger a CD40106 so I might be able to get by with routing the output directly to the Schmitt trigger. If that is too much current I'll go with a transistor.

    Many thanks!

    Kevin
     
  11. radiohead

    Active Member

    May 28, 2009
    474
    31
    if there is too much current for your chip, it can be attenuated by using a resistor (1K or so). Remember, a resistor opposes circuit current. Consult the chip data sheet to determine the acceptable current limits for the chip input pins. Measure the current coming out of the module and use Ohm's Law to calculate the resistor value you will need.
     
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