Published:2009/6/25 20:54:00 Author:Jessie
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Published:2009/6/25 20:54:00 Author:Jessie
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Published:2009/6/25 20:45:00 Author:May
This tester checks transistor for polarity (PNP or NPN). An audible signal will give an indication of gain. Tester can also be used as a GO/NO GO tester to match unmarked devices. (View)
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Published:2009/6/25 20:44:00 Author:May
This circuit provides a low cost and reliable method of testing zener diodes. RV1 can be calibrated in volts, so that when LED 1 just lights, the voltage on pins 2 and 3 are nearly equal. Hence, the zener voltage can be readdirectly from the setting of RV1. The supply need only be as high a value as the zener itself.For a more accurate measurement, a precision pot could be added and calibrate (View)
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Published:2009/6/25 20:42:00 Author:May
Output voltage is proportional to the capacitance connected to pin 2 of the charge pump. The meter works over a range of 0.01 to 0.1 μF with Ra set at 111 K. Over this range of capacitance, the output voltage varies from 1 to 10 volts with a 15 volt power supply. A constant frequency reference is taken from the 60-Hz line. (View)
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Published:2009/6/25 20:41:00 Author:May
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Published:2009/6/25 20:53:00 Author:Jessie
This circuit measures RF voltages beyond 200 MHz and up to about 5 V. The diode should be mounted in a remote probe, close to the probe tip. Sensitivity is excellent and voltages less than 1 V peak can be easily measured. The unit can be calibrated by connecting the input to a known level of RF voltage, such as a calibrated signal generator, and setting the calibrate control. (View)
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Published:2009/6/25 20:40:00 Author:May
With guaranteed 1 pA input bias, the ICL 8007A is ideal as a pH meter or long term sample and hold. (View)
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Published:2009/6/25 20:52:00 Author:Jessie
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Published:2009/6/25 20:38:00 Author:May
This circuit employs a potentiometer as the weight sensmg element.An object placed upon the scale displaces the potentiometer wiper,an amount proportional to its weight.Conversion of the wiper voltage to digital infomation is performed,decoded,and interfaced to the numerlc display. (View)
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Published:2009/6/25 20:52:00 Author:Jessie
A resistive voltage divider is used to es-tablish a bias voltage for the input (pins 2 and 3). The demodulated (multiplex) FM signal is fed to the input through a two-stage high-pass filter, both to effect capacitive coupling and to attenuate the strong signal o f the regular chan-nel. A total signal amplitude, between 80 mV and 300 mV, is required at the input. Its source should have an impedance of less than 10,000 ohms. The Phase Locked Loop is tuned to 67 kHz with a 5000 ohm potentiometer; only ap-proximate tuning is required, since the loop will seek the signal. The demodulated output (pin 7) passes through a three-stage low-pass filter to provide de-emphasis and attenuate the high-frequency noise which often accompanies SCA transmission. The demodulated output signal is in the rder of 50m V and the frequency response extends to 7 kHz. (View)
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Published:2009/6/25 20:52:00 Author:Jessie
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Published:2009/6/25 20:51:00 Author:Jessie
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Published:2009/6/25 20:50:00 Author:Jessie
Loudness detector consists of a 555 IC wired as a Schmitt trigger. The output changes state—from high to low—whenever the input crosses a certain voltage. That threshold voltage is established by the setting of R4. (View)
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Published:2009/6/25 20:34:00 Author:May
The circuit displays drain current versus gate voltage for both P and N-channel JFETS at a constant drain voltge. (View)
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Published:2009/6/25 5:14:00 Author:May
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Published:2009/6/25 5:13:00 Author:May
The Geiger tube needs a high voltage sup-ply which consists of Q1 and its associated components. The transformer is connected in reverse; the secondary is connected as a Hartley oscillator, and RI provides base bias.Dl, D2, C4, and C5 comprise avoltage doubler.RV1 should be set so that each click heard is nice and clean because over a certain voltage range all that will be heard is a continuous buzz. (View)
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Published:2009/6/25 20:49:00 Author:Jessie
The LED is normally lit, but it will be briefly extinguished if the input exceeds a preset (by RV1) level. A possible application is to monitor the output voltage across a loudspeaker; the LED will flicker with large signals. (View)
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Published:2009/6/25 5:11:00 Author:May
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Published:2009/6/25 20:48:00 Author:Jessie
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