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This is a simpler repeating timer circuit. It uses just one Cmos IC - wired as an asymmetric oscillator. The length of time the relay remains energized - and the length of time it remains de-energized - are set independently.... [read more]

A simple circuit, High-Pass filter, variable between frequencies 20HZ until 200HZ, useful in a lot of cases elaboration of sound signals. The regulation is achieved with the double potesometer 47KΩ and the frequency response in his two extreme places, appears in the schematic.... [read more]

This circuit was designed and manufactured the '80's. From then it works without problem. It does not present any particular constructional problem, beyond known: the attention in the provided force of power supply - choice suitable heatsink and good matching of drivers transistor.... [read more]

The bi-directional sequencer uses a 4 bit binary up/down counter (CD4516) and two "1 of 8 line decoders" (74HC138 or 74HCT138) to generate the popular "Night Rider" display. A Schmitt Trigger oscillator provides the clock signal for the counter and the rate can be adjusted with the 500K pot.... [read more]

The circuit requires a double pole, double throw relay in conjunction with a single transistor to allow toggling the relay with a momentary push button. One set of relay contacts is used to control the load, while the other is used to provide feedback to keep the relay activated or deactivated. Several push buttons can be wired in parallel to allow toggling the relay from different locations.... [read more]

Many times we needed a variety of voltages, from a battery 12V. With the circuit, we can take voltages smaller or bigger, positive or negative, from a battery 12V.... [read more]