VU Meter

LED VU Meter

Although there are several ICs on the market with which it is quite simple to construct an LED VU meter, there is, no doubt, still interest in building such a meter from discrete components. The meter shown in the diagram is based on eight opamps, contained in two Type LM324 chips, which function as comparators.[…]

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wave converter

Sine Wave Converter

The converter based on a Type CA3080 operational trans-conductance amplifier (OTA) converts a triangular voltage into a sinusoidal one with very low distortion. An OTA is a device whose amplification can be varied by a control current. The circuit needs a stable, precisely symmetrical supply voltage, since the control is derived directly from this via[…]

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test probe

General Purpose Test Probe

The compact test probe is made from five transistors, three LEDs, a zener diode, and three resistors. It enables rapid ‘measurement’ of voltage levels at digital gates, fuses, diodes, batteries, and others. Of course, it does not provide absolute values, but rather a good indication of correct operation or otherwise. Measurements are carried out with[…]

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Fuse monitor

Fuse monitor

When an appliance ceases to —K operate, there may be various causes for this, one of which is the blowing of the mains fuse. The monitor proposed here contains an LED that lights when that is the case. It is suitable for use with fuses rated from milliamperes to amperes. As long as the fuse[…]

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rt200rep_2_full

RC- 5 infra-red receiver for 80C32 computer

‘RC-5’ is the Philips/Sony standard the received bits are shifted into a 16-hit reg-(JUL” for infra-red (IR) remote control of consistent formed by R4 (low) and R5 (hi0). The audio /video equipment (Ref. 1). The second start bit becomes the MSB. When the circuit and the listing were given enable the 80C32 received word is[…]

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PC fan control Circuit

PC fan control Circuit

It is an unfortunate and well-known fact that most PCs of IBM and compatible type make a lot of noise. which is both undesirable lots of noise in the both undesirable (as regards noise in the working environment) and unnecessary (as regards the actual power consumptions. which is often quite low ), many fans in[…]

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Solid State

Solid State Voice Recorder

Integrated circuits ISD 1012, ISD 1016 and ISD 1020 from chip maker ISD enable sounds to be recorded and played back. The final two digits in type coding show the length of a sound message in seconds. The difference in recording and playback is caused by the sampling frequency. which is highest (10.6 kHz) for[…]

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