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

 

My guess is those are just general purpose outputs, ie. on/off high/low signals. So you need an external relay.

 

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?

 

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?

 

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?

Here is a link to the manual that came with the module.

 

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

 

By the way, what are the markings on that chip?

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

Kevin

 

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

 

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.

 

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.

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

 

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.