Found in 1980s Radio Electronics, this circuit triggers the ignition of a rocket after the countdown is completed. The countdown is monitored by the sequential lighting of LEDs
This oscillator version is from an RCA documentation from the 1970s. Transistors support modern...
High selectivity filters can be obtained by combining same frequency crystals in series as shown...
This circuit was published in an article in Radio Electronics magazine in October 1988. It uses...