Published:2009/6/26 2:10:00 Author:May
This simple circuit generates both white and pin noise. Transistor Q1 is used as a zener diode. The normal base-emitter junction is reverse-biased and goes into zener breakdown at about 7 to 8 volts. The zener noise current from Q1 floirs into the base of Q2 such that an output of about 150 millivolts of white noise is available. To convert the white noise to pink, a filter is required which provides a 3 dB cut per octave as the frequency increases.Since such a filter attenuates the noise considerably an amplifier is used to restore the output level. Transistor Q3 is this amplifier and the pink noise filter is connected as a feedback network. between collector and base in order to obtain the required characteristic by controlling the gain-yersus-fre quency of the transistor. The output of transistor Q3 is thus the pink noise required and is fed to the relevant output socket. (View)
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Published:2009/6/26 2:08:00 Author:May
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Published:2009/6/26 2:08:00 Author:May
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Published:2009/6/26 2:07:00 Author:May
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Published:2009/6/26 2:07:00 Author:May
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Published:2009/6/26 2:04:00 Author:May
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Published:2009/6/26 2:04:00 Author:May
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Published:2009/6/26 2:03:00 Author:May
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Published:2009/6/26 2:02:00 Author:May
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Published:2009/6/26 2:02:00 Author:May
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Published:2009/6/26 2:02:00 Author:May
This dual astable multivibrator provides versatility not available with single timer circuits. The duty cycle can be adjusted from 5% to 95%. The two outputs provide two phase clock signals often required in digital systems.It can also be inhibited by use of either reset terminal. (View)
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Published:2009/6/26 2:00:00 Author:May
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Published:2009/6/26 1:59:00 Author:May
Before power is applied, the input and output are at ground potential and capacitor C is discharged. On power-on, the output goes high (VDD) and C charges through R until Vis reached. the output then goes low (VSS). C is now discharged through R until Vn is reached.The output then goes high and charges C towards Vp through R. Thus input A alternately swings between Vp and Vn as the output goes high and low. This circuit is self-starting at power-on. (View)
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Published:2009/6/26 1:57:00 Author:May
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Published:2009/6/26 1:56:00 Author:May
The capacitor C will charge through RA and RB, and then discharge through RB only.The duty cycle may be controlled by the values of RA and RB. (View)
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Published:2009/6/26 1:56:00 Author:May
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Published:2009/6/26 1:54:00 Author:May
If the output is low, application of a negative-going pulse to the trigger input sets the flip-flop (Q goes low), drives the output high, and turns off 1. Capacitor C is then charged through Ra until the voltage across the capacitor reaches the threshold voltage of the threshold input. If the trigger input has returned to a high level, the output of the threshold comparator will reset the flip-flop (Q goes high), drive the output low, and discharge C through Q1. Monostable operations is initiated when the trigger input voltage falls below the trigger threshold. Once initiated, the sequence will complete only if the trigger input is high at the end of the timing interval. (View)
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Published:2009/6/26 1:52:00 Author:May
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Published:2009/6/26 1:51:00 Author:May
As the speed of an electric drill is decreased by loading, its torque also drops. A compensating speed control like this one puts the oomph back into the motor. When the drill slows down, a back voltage developed across the motor-in series with the SCR cathode and gate-decreases. The SCR gate voltage therefore increases relatively as the back voltage is reduced. The extra gate voltage causes the SCR to conduct over a larger angle and more current is driven into the drill, even as speed falls under load. The SCR should be mounted in 1/4-in. thick block of aluminum or copper at least 1-in. square. If the circuit is used for extended periods use a 2 inch square piece. (View)
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Published:2009/6/26 1:50:00 Author:May
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