Hi,
I'm working on a wireless PIR module on ATTiny85 which send alarm signal via RF 433 Mhz. I tried my circuit on a breadboard and it worked fine (sending and receiving data worked correctly). Then I solder components to universal board and transmiter stop sending data correctly (receiving nothing).
I checked connections and voltage levels and everything is ok. PIR module and ATTiny85 works correctly. Interesting thing is that when I touch coils of RF 433 transmitter it start sending correct data (on the serial monitor of Arduino Uno where receiver is connected).