Parts nos are ZW-3100, ZW-3102.
Low power 433 MHZ modules , data rate up to 10 kbs.
Just wondered what to drive them with just to implement a simple remote controlled switch to turn on and off some solar powered water solenoids.
Haven't played with these specifically, but they look similar to the Oatley Electronics ones being flogging off some time back.
Basically, they're designed for serial data (be it 232 or whatever), but I found there to be no squelch of any sort, and the receiver was noisy at best with no signal input. In other words, if you were not transmitting a stream of data, you'd get random noise out of the receiver, so you need some error checking / data validity checking at the receiving end if you want to use them in this manner. It makes things a bit more complicated if you didn't need data transmission of any real complexity to start with.
If the data never ends, as in a continuous stream, there's no problem.
As I said, I played with the Oatley ones a while back, the Jaycar ones may be (hopefully) different. The data sheets for the Jaycar ones are no more helpful than the ones I played with- so can't help there.
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First thing to know is you have to put a antenna on them of about 20cm. some people just put the moddules in and wonder why they only go 10cm. so make sure thats ok for what you want to do with them. The reciever seems to auto lock somehow onto nothing and output rubbish, so its important that you send a preample to give it time to adjust and then data and then CRC or parity etc. if you are doing packet bursts. You can't just continously send a contantly data value, it has a minimum bit rate and if you don't have enough state changes it seems to wonder away from the frequency it has locked to looking for data and ends up outputting rubbish again.
I made a on/off switch with no microcontroller at the RX by having the data line add to the charge of a cap each time the output was positive. A seperate really slow oscillator would then discharge the cap if not enough high data bits were reieved in a certain amount of time. If the data cap got charged high enough it would toggle a flip flop. So randomly I would typically reicieve say 50% high and lows, so I set the thing to toggle over if say 85% of bits within a certain time (say 0.5 seconds) where all high. Then I would just send say 0x7FFF (93% bits high), which is enought to keep it from wondering away. Haven't had it false trigger that I have seen anyway :-D
just buy and stuff around with them they are only $10 each and lots of fun!
Jaycar also have a wireless doorbell cat# LA-5018 which uses 433 MHz, but costs about 30% less than bare modules in NZ. It is quite hackable and I've used one by replacing the bell press with my own switch arrangement. Works OK through 50m of bush in the back yard with no additional antenna.
cheers, Ron
Thansks all for the info. The doorbell idea sounds like the simplest solution.
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