Power for the delay circuit is derived directly from the mains by a bridge rectifier, D1-D4. The rectifier must be able to handle a current of up to 1 A. For safety reasons, resistor R1 ensures that capacitor C1 is discharged rapidly when the mains is switched off. The resistor should, therefore, be rated at[…]
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Power-on delay
The power supply for this analogue circuit, which affords delays of up to 330 seconds, is taken directly from the mains. The direct voltage at the output of the bridge rectifier is held at 22 V by zenzer diode D5. Resistor R6, which enables C1 to discharge rapidly as soon as the mains is switched off, must[…]
Read moreOverload Indicator
The overload indicator consists of a window comparator that measures the magnitude of an a.f signal. Two of the opamps contained in a TL072 is supplied with a reference voltage by potential divider R1-R2-R3-P1. The outputs of the opamps drive T1 via diodes D1 and D2 (that function as the half-waved rectifier), which in turn actuates D3.[…]
Read moreAmplification/attenuation selector
A Type TL081 opamp and some passive components are sufficient to construct a small amplifier whose amplification can be varied between +1 to -1 with a potentiometer – see the diagram. The input signal is applied to both inputs of the opamp: to the inverting input via C1 and R1, and to the non-inverting input via[…]
Read moreDigital (tape) Counter
Since there are still tape records about that have no mechanical tape counter, the circuit shown here offers an excellent, electronic add-on for these. It can, of course, also be used to replace a mechanical counter. Furthermore, it can be used for other applications, for instance, as the hoist-height indicator for a model building crane,[…]
Read moreEE 43-100 FINAL PROJECT-AN AUDIO AMPLIFIER
EE 43/100 FINAL PROJECT: AN AUDIO AMPLIFIER Part 2: Audio Amplifier Lab Guide In this lab, we’re going to extend what you did last time. We’re going to use your AC to DC converter to power an audio amplifier. Important: we’re going to be playing around with the audio amplifier in this lab, and it’s[…]
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