I have a 433mHZ transmitter and receiver. The transmitter gets its power from a 12v boost regulator which is connected to two 18650 3.7v 3700mA batteries in parallel. I am running the transmitter signal through an HT12E. The HT12E is connected to an 8 pole DIP switch for addressing.
The receiver is powered through a 5v regulator which gets it power from a 24v center tap transformer. I bring the two 12v lines in through two 1N4007 diodes and then tie them together on the positive side of a 1000uf capacitor. The center ground is attached to the ground of the capacitor and then to the ground of the regulator. The receiver is connected to a HT12D. And the HT12D is attached to an 8 pole DIP switch to match the address of the transmitter.
When a sensor detects a certain condition an Arduino Mini Pro activates a relay providing power to the transmitter. Five seconds later the Arduino activates another relay which disconnects the AD1 pin on the HT12E from ground sending a pulse to the transmitter. The reasons for the two relays is for lowering power consumption.
When the pulse is received by the receiver it is sent to the HT12D and then the LED lights up.
I am trying to get this to work at around 20 meters. I can get around 12 meters but there I am stuck. I have tried many things to increase the distance. I am using solid copper wire of 173mm for both transmitter and receiver antennas solder directly to the boards. I have placed .1uf ceramic capacitors for output bypass capacitors on both regulators. Anthony Cartwright suggested 10uf capacitors on between both regulators input + and grounds as well an additional 10uf capacitors on the + and ground of the transmitter and receiver themselves. I have tried all of these ideas with very limited success. Sometime the distance may go up to 14meters but nothing in the range of 20 to 200 meters claimed. I have tried using a separate rectified 12v input on the receiver but with no real improvement. Can someone suggest something.
The transmitter I am using has an output power of 10mA. I have ordered one that is rated at 25mA. That may help some but not enough I’m afraid.
I am including a schematic. I have put black X where the 10uf capacitors are and a blue dot where the .1uf capacitors are. If anyone has an idea(s) Please help.