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A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes.... [read more]

A peak level indicator when a signal exceeds a certain maximum value. It can be quite useful, for instance, with tape recorders, mixing consoles etc. One of the most important requirements of a peak level indicator is that it should respond to very short signals.... [read more]

This circuit provides a visual 9 second delay using 10 LEDs before closing a 12 volt relay. When the reset switch is closed, the 4017 decade counter will be reset to the 0 count which illuminates the LED driven from pin 3. The 555 timer output at pin 3 will be high and the voltage at pins 6 and 2 of the timer will be a little less than the lower trigger point, or about 3 volts.... [read more]

This is a very simple, low cost, Hi-Fi quality power amplifier. You can build it 5 ways, like it’s shown in the table (from 20 W to 80 W RMS).... [read more]

High Current Power Supply... [read more]

This circuit of measurement of level uses the UAA180 of SIEMENS and a circuit of rectification of precision, round the IC2B. The calibration has become in steps 3db from the one Led in the other, ensuring, a very good rate of precision, in the measurement of entering acoustic signals. The Led can be square, thus when they are placed the one by in the other, they give the picture of bar, without space.... [read more]