Mains frequency is pretty stable and it is unlikely that you have to measure it but if you have an emergency generator you might find this circuit useful as it will give an indication whether the generator is running too fast or too slow. Actually you can use the mains frequency to calibrate it by adjusting the 25K multiturn trimmer until it reads 0. The odd looking components values are easily obtained using standard values: 3777 is 3900 in parallel with 120K?, 4020 is 3900 and 120 in series, 570nF is 470nF with 100nF in parallel and 400nF is 4 x 100nF capacitors in parallel. Components should be chosen for their stability and precision. 1% tolerance would be ideal but 5% is acceptable so long as you measure them with a good meter.

In this circuit, the wearer assembly consists of only one lamp, 6V6 or 6L6, which acts as an oscillator and as an output amplifier at the same time. Coil L1 is the medium wave oscillation coil. Of 6SA7. The coil L2 consists of 50 spools wrapped on a cylinder covered with a 3 cm diameter insulating material. The diameter of the wire is 0.5mm. The capacitor C1 is a double variable air of 1000pF (connect the two capacitors in parallel). C1 itself is C2. Through C1 and C2 we tune the transmitter from 2MC to 600KC.

In order to eliminate noise, I`ve used a 100uF capacitor and a 100nF bypass capacitor across the supply and two 10nF capacitors in parallel with the resistors Rda and Rdb (those are 10K each), As for the current limiting, I`ve used a 22K resistor paralleled with a 10nF capacitor, from pin 3 (Ilim) to V-. I`ve tied pin 7 (E/S) to V+. I`ve used two

The Cockroft-Walton multiplier uses a cascaded series of diodes and capacitors to generate a high voltageDC potential from anAC input through acircuit topology thatuses diodes to charge capacitors in parallel and discharge them in series. The output polarity of the Cockroft-Walton multiplier depends on the way in which its diodes are oriented, so

The two unspecified polarized capacitors (one directly above the transformer and one directly to the right of the transformer) are actually each a pair of 470 µF capacitors in parallel (for a total of four 470 µF capacitors). These capacitors MUST be Low-ESR types for the power supply to function properly. Figure 4: The two 100 µF 16V