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Topic: Power supply issues with cheap 433mhz receiver (Read 359 times) previous topic - next topic

basjuh31

Hi guys, happy new year!

Hope you can help me out on this one: I'm fairly basic when it comes to Arduino and I try to set up some home automation system just for fun. The plan is to use a Raspberry Pi as a webserver from which I can control lights/heating/etc.

The following problem got me stuck, but before I'm going to give up, I want to take the chance to ask you expert guys:

I bought these really cheap 433mhz receiver/transmitter kits from China. I made a setup where one Arduino would send a command using the VirtualWire library to another Arduino which then switches a relay (so basically it's just a remote switch). In my testing environment this worked perfectly, I was able to send/receive and then switch the relay, so I tried to build it in a small box and solder this all together. That didn't work and after some testing, it seems that the receiver only wants to receive data on some power-supplies. I bought some cheap 5v usb power-supplies because I didn't want it to cost way more than a regular remote-switch system that you can find in stores, but these cheap power-supplies seem to give problems.

After some testing I found out that my iPhone charger worked great, some other USB charger did work sometimes (it received a signal only half of the time) and some chargers (the more cheap ones) didn't catch a signal at all. The Arduino boards will show that they're powered, relays switches on startup, but don't do anything when I try to send a signal.

I've found some information about noisy power-supplies which maybe distort the receivers, but I'm not sure if that applies to this case and if I can do something to help that (found something about decoupling capacitors?).

Is this a common problem or does someone has had similar experiences? Is there a way to be able to use the cheaper power supplies?

Thanks a lot guys,
Bas  ;)

sp_mike

I can't comment on the receiver, but I am successfully using one of these cheap usb power supplies to power my Uno and a 433 Mhz transmitter that is used to turn on/off two cheap wireless AC sockets, for outside lighting. This configuration has worked flawlessly with not a single glitch. I had my doubts about these power supplies, but so far so good.

mauried

Make sure the supply voltage to the receiver is as close as possible to 5V.
They lose sensitivity as the voltage shifts either side of 5 V.



basjuh31

Thanks guys, really appreciate it! The problem seems to be at the receiver only indeed (transmitter works on all power supplies), and I'm definitely going to try to shorten the power supply cables to check if that might be the problem. Will post results here!

Is it possible that the receiver is super picky about the amount of voltage and the cheap power supplies are not that exact?

CrossRoads

I power one of those transmitters from a LiPo battery, output ranges from 4.2V fully charged down to 3.7V.
Receiver is powered from 5V wallwart. 
Do you have antenna on then also? I used 17cm of 30 AWG wirewrap wire.

Did you put a meter on the supply to confirm it's actually 5V?
You could also add some caps from 5V to Gnd, 10uF for big ripples, and 0.1uF to catch higher frequency stuff.  Right across the receiver VCC & Gnd pins.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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