I purchased this transmitter/receiver pair…
robotshop.com/on-shine-high-sensitivity-tx-rx-4.html
When I connected only the receiver. (just to power)
pin 1 = ground
pin 5 = +5v
I get 2.5 volts across pins 1 and 2,
and 2.5v across pins 2 and 5
pin 2 is the output, I thought I would have nothing on that pin until I energized the transmitter.
In addition, you can see in the online notes, that pin 3 is normally low. I checked that, and pin 3 show continuity to ground.
I don’t know if I’m doing something wrong, if my expectations are wrong, or if it’s defective.
Help.
The receiver is not picking up a strong transmitter signal so it is picking up 433Mhz noise basically. There are all sorts of radio waves floating around in that frequency range from garage door openers to R/C toys. Some household electronics also emit radio waves that can be picked up.
When you read that a pin is normally low, that means it is tied to ground (0V), so this is normal.
Is the Transmitter sending data?
This is why most people will opt to encode the signal fed into the TX, in order to recognise it from “junk” on the RX side. If you think of a garage door opener (for which this module may be used), there are dip switches to assign a “channel”. This makes the TX send a distinct code that the receiver must be expecting. It basically ignores any other data it perceives.
Another thing to verify is the wire antenna you are using, this can sometimes cause a problem.
I’m not sure it would work honestly.
We suggest a 6.5 Inch piece of 22 to 32 guage solid insulated wire for the antenna.
