433.92Mhz Transmitter problems - no signals detected

That does seem very strange - my transmitters seemed to work over a pretty long range (and they look identical). I'm not sure about the circuit on the transmitter but it could be that it actually needs 5v on the data pin in order to transmit properly.

To do that:

• Make sure you're using a pin from http://www.espruino.com/ReferenceESPRUINOBOARD that doesn't say 3.3v by it
  
• Connect a 1k resistor between that pin and the 5v line
  
• Use the command pinMode(YOUR_PIN, "opendrain") before you do anything
  
  

Now you'll get a full 5v swing on the output.

Other thing is some of the modules actually have a hole labelled 'ANT'. If you solder a piece of wire onto there it might really help (you'll have to google what the length should be for 433Mhz)