I am interested in transmitting sensor voltage from a LM34 temperature sensor to a display device that uses the D.C. voltage from the sensor. It is a display using an ICL7107 three and one half Digit, LCD/LED Display, A/D Converter that converts the D.C. voltage from the analog sensor to drive some 7-segment VFD tubes. Right now the indicator is using the normal D.C. voltage from the sensor and is hard wired to it and works fine. I need to reproduce that analog voltage at the receiving end to drive the indicator over a short distance. Any help appreciated.
This project may be an example of what you want: http://www.gammon.com.au/forum/?id=12821
I use a similar approach, but instead use the very cheap and simple 433 MHz TX/RX modules and the VirtualWire library.
Historically the simple way of doing this was to use a voltage-to-frequency converter and transmit that frequency and then at the receiver, use a frequency to voltage converter and use the voltage however it’s needed.
Those V/F F/V converters are all but obsolete these days and hard to find. You can do the same thing with a cheap Arduino or AVR (e.g., a Tiny45). Read the voltage with the onboard A/D converter and convert it to a pulse stream at a frequency that varies perhaps 1kHz/volt. At the receiving end, count the number of pulses received per second and convert the pulse frequency back to a voltage.
There are more sophisticated methods of encoding the data but this is probably the simplest that will work.
Look at the devices here:
http://www.anarduino.com/details.jsp?pid=148
Their site is not always updated but the devices are unbelievably inexpensive.