Radio. - Here is Circuit Schematic and Project The RC link and ASK environment. Radio Control /Remote Control and ASK (Amplitude Shift Keying) /OOK (On /Off Keying) have been around for some time, but there is limited coherent information on the subject and the associated hardware. Applications abound, including garage door openers, keyless entry, R-C toys, etc. These all utilize one-way communications. The most commonly used frequencies are 315, 330 and 434mHZ (most popular).
The transmitter consists of a SAW resonator configured as an oscillator.
The circuits all appear to be similar, but the layout varies depending upon the manufacturer –copies abound. The recommended supply voltage is 3 to 12V with power and range a function of the voltage. One neat thing about the transmitter is that they draw No (zilch) current when not operating because the keying transistor must be On to complete the circuit. Actual CW current runs between 9mA @ 3V to 40mA @ 12V, but that is a non-issue because it runs only when the push-button is pressed so the battery will likely never need replacing. Maximum legal RF power output is 10mW –with input power being up to 480mW, the efficiency must be low (or perhaps nobody really bothers to regulate such).