Published:2009/7/19 23:22:00 Author:Jessie
Trigger switch flasher. The flasher circuit is activated whenever pushbutton switch S1 is pressed. The circuit is a two-stage direct-coupled amplifier working as a multivibrator (courtesy General Electric Company). (View)
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Published:2009/7/19 23:22:00 Author:Jessie
In this application, the LM3909 switches to, and holds its condition, whenever the switch changes sides-even if the contact is momentary. This results in an output that remains in the 0.3-V (on) or 2.9-V (off) condition. (View)
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Published:2009/7/10 1:59:00 Author:May
This circuit modulates the current through a lamp filament. Use a low-voltage lamp with a thin, straight filament. They have a fast response to ftlament voltage variations. dc is applied to bias the fila-ment that is on, and the audio is superimposed. A BC457 drives a TIP147, which modulates the filament current. (View)
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Published:2009/7/19 23:21:00 Author:Jessie
Timebase integration of a variable is performed by counting cycles of saturable-reactor oscillator whose frequency is proportional to the variable. linearity is within 1% of full scale.-L. W. Langley, Saturable-Core Oscillator Integrates Gas-Flow Data, Electronics, 32:4, p 42-43. (View)
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Published:2009/7/10 1:58:00 Author:May
Integrated circuit U1 is connected as a low-frequency asymmetrical oscillator. Its output is inverted by Q1 and fed to the reset terminal of U2 at pin 5. Integrated circuit U2 is configured as an audio oscillator and is enabled when the output of UI is low. With the voltage at pin 5 of U2 constant, the circuit just bleeps. The voltage across capacitor C1 is fed to the base of Q2, which turns it on and grounds pin 5 of U2. When the frequency of the reset signal on pin 4 falls, the output frequency of U2 rises. The output then becomes a whoop, starting low in frequency and ending high. Resistor R1 sets the repetition rate and R2 determines the time duration of the whoop. Resistors R3 and R4 set the center-operating frequency. (View)
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Published:2009/7/10 1:58:00 Author:May
Uncapped pnp germanium alloy junction transistor placed in strong mognetic leld shows gain variation with fiux density, with direcion and amount of gain depending on direction of magnetic leld.-R. W. Lade et al., 37:31, Magnetic Fields Vary Transistor Goin, Electronics, 34:5, p 68-70. (View)
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Published:2009/7/10 1:58:00 Author:May
Feedback from Q2 to let Q1 boosts input impedance.-B.Down, Using Feedback in FET Circuit to Reduce Input Capacitance, Electronics,p 63-65. (View)
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Published:2009/7/10 1:57:00 Author:May
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Published:2009/7/10 1:57:00 Author:May
Noise figure is only 4 db for generator resistance of 200 ohms.-D. Hall, Using Epitaxial Transistors in Switching and R-F Circuits, Electronics, 34:13, p 52-53. (View)
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Published:2009/7/10 1:56:00 Author:May
Using a pickup coil to drive an amplifier (IC3A-B-C-D), this meter circuit can be directly calibrated in field-intensity units. R3/C3 and R12/C7 establish a frequency roll off that compensates for the pickup-coil sensitivity, and set a 20-kHz cut-off point. S2 is the range-select switch. L1 is an 18-turn 3 diameter coil.The frequency range is 50 Hz to 20 kHz and the range of measurement is 0.1 to 20000 microlbsiers (μT). (View)
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Published:2009/7/10 1:56:00 Author:May
This is a two-state or on/off-type siren where the LM13080 oscillates at an audio frequency and drives an 8-0 speaker. The LM339 acts as a switch which controls the audio burst rate. (View)
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Published:2009/7/10 1:56:00 Author:May
Epitaxial 2N743 is operated Gammon-emitter at signal frequency and Gammon-base for biasing. Unneufralized gain per stage is 17 db.-D. Hall, Using Epitaxial Transistors in Switching and R.F Circuits, Electronics, 34:13, p 52-53. (View)
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Published:2009/7/10 1:55:00 Author:May
This low-cost 1-package siren has one VCO, and the other oscillator generates the voltage ramp to vary the frequency at the VCO output. All components within the dotted line are part of the IC. (View)
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Published:2009/7/10 1:55:00 Author:May
This voltage to current converter uses three op amps to drive a pair of power transistors. The current output is calculated as:
IOUT=Vin/R6
Output resistance is over 50 MΩ. IOUT can range from 1 mA to the current ratings of T1 and T2. (View)
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Published:2009/7/10 1:55:00 Author:May
This circuit uses one of the LM389 transistors to gate the power amplifier on and off by applying the muting technique. The other transistors form a cross-coupled multivibrator circuit that controls the rate of the square-wave oscillator. The power amplifier is used as the square-wave oscillator with individual frequency adjust provided by potentiometer R2B. (View)
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Published:2009/7/10 1:55:00 Author:May
Noise figure is only 6 db for generator resistance of 150 ohms.-D. Hall, Using Epitaxial Transistors in Switching and R-F Circuits, Electronics, 34:13, p 52-53. (View)
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Published:2009/7/10 1:54:00 Author:May
An optical receiver for light-wave communications, this circuit works with AM-type light signals. (View)
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Published:2009/7/10 1:54:00 Author:May
Output is 20 v peak-to-peak into 1,000 ohms, down to 5 cps, with high stability.-R. W. Johnson, Circuit with a Twist: The cascode 36:49,p 69-70. (View)
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Published:2009/7/10 1:53:00 Author:May
This circuit uses a Linear Technology LT1073 in a -24-V converter. The supply can be two AA cells (3 V) or 5 V. The circuit can deliver 7 mA. (View)
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Published:2009/7/10 1:53:00 Author:May
This circuit uses a CMOS chip and a VMOS FET amplifier for 6 W of audio output. 18 W of audio canbe generated usmg a+24-Vdc supply, IC1A and IC1B are used as a 1-Hz oscillator. IC1C and IC1D form a 1-kHz multivibrator that is gated by the 1-Hz signal from IC1A and IC1B. (View)
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