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The EQ-2 it is a circuit of graphic equalizer 6 band of regulation. Each band is regulated from the potesometers RV1-6, that are, for better optical indicate of regulations, Fader. This does not mean that we cannot him replace with simply potesometer. In the center of regulation potesometer, the gain is null (flat), but in terminal has +/- 15 db, boost or cutting off, respectively. For stereo operation, it will be supposed two times.... [read more]

The circuit of graphic equalizer, allocates ten adjusting potesometer , that each one from them affects in a predetermined area of frequencies, the central frequency of which abstains a octave (double), from the central frequencies of her neighbouring regions. Each unit has common materials with remainder and it differs only in the capacity of capacitors that constitutes the filter in each unit.... [read more]

A simple way to see if a fuse has blown without removing it from its holder.... [read more]

This is a small electronic switch that connects a battery to the equipment for a certain amount of time when a push-button is momentarily pressed. And we have also taken the ambient light level into account; when it is dark you won’t be able to read the display so it is only logical to turn the switch off, even if the time delay hasn’t passed yet. The circuit is quite straightforward. For the actual switch we’re using a well-known MOSFET, the BS170.... [read more]

Another method of using opamps to regulate a power supply is shown. The power transformer requires an additional winding to supply the op-amps with a bipolar voltage (+/- 8 volts), and the negative voltage is also used to generate a reference voltage below ground so that the output voltage can be adjusted all the way down to 0. Current limiting is accomplished by sensing the voltage drop across a small resistor placed in series with the negative supply line.... [read more]

Typically the op-amp's very large gain is controlled by negative feedback, which largely determines the magnitude of its output ("closed-loop") voltage gain in amplifier applications, or the transfer function required (in analog computers). Without negative feedback, and perhaps with positive feedback for regeneration, an op-amp essentially acts as a comparator. High input impedance at the input terminals (ideally infinite) and low output impedance at the output terminal(s) (ideally zero) are important typical characteristics.... [read more]