Published:2009/7/9 3:52:00 Author:May
Zener diode D1 is used to suppress the ftrst 6 V of the scale, which gives a meter reading of 6 to 8 V-useful for automotive electrical system monitoring. (View)
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Published:2009/7/9 3:52:00 Author:May
You can transform a 741S124 multivibrator into a wideband VCO by replacing it conventional ftxed capacitor with a variable-capacitance diode. The only disadvantage of this scheme is the 30-V biasing volt-age that the diode requires. Capacitors C1 and C2 couple the Philips BB909A variable-capacitance diode to the 74S124. R1 and R2 are large enough to isolate ground and control voltages from the timing capacitors. Resistors R3 and R4 form a voltage divider for the 74S124's control input. (View)
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Published:2009/7/20 6:25:00 Author:Jessie
Use of two different sizes of charging capacitors in series increases effective gain up to 10,000 times that of conventional ujt/scr phase-control circuit. Eliminates amplification.- Transistor Manual, Seventh Edition, General Electric Co., 1964, p 332. (View)
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Published:2009/7/9 3:51:00 Author:May
This circuit uses a digital voltmeter (formed from IC1 and IC3) to display fuel quantity as a percentage of a full tank. In order to work with two kinds of fuel sensors, low resistance = full. Where higher resistance full, IC2 forms a dc amplifier that has both inverting (path A) or noninverting (path B) outputs, and calibration adjustments for each path. (View)
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Published:2009/7/9 3:51:00 Author:May
Using an EXAR XR2206, this generator will produce sine, square, and triangular waves from 10 Hz to 100 kHz. U1 is the XR2206 chip, R7 controls frequency, and 55 through 58 select the frequency range. U3 produces a TTL-compatible square-wave output, while U3C and D produce a sync signal for scope use. U2 is a frequency/voltage converter that is used to drive analog meter M1, which reads the generator frequency. (View)
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Published:2009/7/9 3:49:00 Author:May
In this circuit, a waveform generator is used as a stable VCO in a Phase-Locked Loop (PLL). (View)
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Published:2009/7/9 3:47:00 Author:May
A bridge circuit is used to produce a signal from the output of vacuum sensor IC1. IC2b provides about a 0.2 V offset for IC4, the A/D converter. IC2b and d are voltage followers that drive differential amp IC2a. The output of this circuit is used to drive IC4 and IC1, the display drivers. (View)
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Published:2009/7/9 3:45:00 Author:May
The 555 acts as the tone generator configured in the astable mode. Its pin 3, square-wave output is transformed into a triangle wave by R1 and C2. The voice's pitch is controlled by R1. Transistor Q1 can be 2N1086, 2N1091, or any other equivalent npn germanium type. Sounds are amplified by the 741, and the IC's output drives the transistor to saturation. When the transistor is in the saturated state, the triangle wave is able to reach the speaker, and your new voice can be heard. (View)
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Published:2009/7/9 3:45:00 Author:May
This little tester is useful for checking vehicle electrical circuits. Two LEDs indicate whether one of the clips is connected to the positive supply line (red) or to ground (green).
The unit is powered by the vehicle battery. It is advisable to terminate the unit into two insulated heavy-duty crocodile clips. These enable connection to be made directly to the battery or to terminals on the fuse box.It is also possible to terminate it into a suitable connector that fits into the cigarette lighter socket. If a sharp needle is soldered to one of the terminals, it is possible to check insulated wiring-but only those that carry 12 V.
Although the needle pierces the insulation, it does not damage it. (View)
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Published:2009/7/20 23:45:00 Author:Jessie
36 MHz RFamplifier using a 3N211 dual-gate MOSFET(courtesy Texas Instruments Incorporated). (View)
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Published:2009/7/9 3:41:00 Author:May
This gauge is similar to the miscellaneous temperature gauge, except that a thermostat is used as a sensing element. (View)
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Published:2009/7/20 7:34:00 Author:Jessie
Miniature 2128 lamp with low-mass filament triggers light-activated scr in 1 millisec when lamp is across scr and in about 3 cycles at low a-c lamp voltage. Potentiometer thus provides phase control of scr for dimming 25-w lamp or equivalent-wattage load.-E. K. Howell, Light-Activated Switch Expands Uses of Silicon-Controlled Rectifiers, Electronics, 37:15, p 53-61. (View)
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Published:2009/7/20 7:34:00 Author:Jessie
45 MHz RF post amplifier using two 3N204 dual-gate MOSFETs (courtesy Texas Instruments Incorporated). (View)
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Published:2009/7/20 7:33:00 Author:Jessie
Holds photodetector output signal constant within 2 db for 4-db variation in ambient light level. -P. H. Sydenham, Photodetector Gain Control Aids Signal Discrimination, Electronics, 38:23, p 111. (View)
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Published:2009/7/20 7:32:00 Author:Jessie
25-watt UHF microstrip amplifier for 450 to 470 MHz (courtesy Motorola Semiconductor Products Inc.). (View)
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Published:2009/7/20 7:31:00 Author:Jessie
Amplitude modulator using an AM1545G wide-band amplifier (courtesy Motorola Semiconductor Products Inc.). (View)
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Published:2009/7/9 3:40:00 Author:May
A Teledyne TSC9400 provides 0-to-1-V output from a 0-to-10-kHz input.A single +15-V supply is used,Linearity is 0.25% to 10 kHz. (View)
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Published:2009/7/9 3:40:00 Author:May
The circuit, a general-purpose system with many uses, vocalizes 59 allophones contained in the speech processor. After filtering and amplification, its pulse-code-modulated output can drive an 8-Ω speaker. The processor's address pins, A1 to A6, define 64 speech-entry points.Closing the test switch to the NAND gate lowers its output, thereby loading an address and triggering the ALD input for an allophone cycle. The CD4520 dual binary counter, IC2, counts from 0 to 63 in binary code until its Q7 output resets it on the number 64 count. To generate a phrase, just add an EPROM between IC2 and IC3 that contains a program for a predetermined sequence of allophones. (View)
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Published:2009/7/9 3:39:00 Author:May
This gauge uses a sensor in conjunction with R1 to develop a dc voltage proportional to oil pressure. IC1 and IC2 form a two-digit DVM. Q1 and Q2 are display selectors for the multiplexed display. IC1 provides the necessary +5V to the circuitry. Calibration is via R11 and zero adjust via R17. (View)
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Published:2009/7/9 3:35:00 Author:May
This amplifier is useful for audio and video applications. Gain is set by Rf and the voltage gain of this amplifier is approximately 1 +Rf/560, where Rf is in ohms. Bandwidth depends on gain selected, but typi-cally it is several MHz. Rf=5.1 kΩ, which produces a gain of 10x (20 dB) voltage. (View)
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