Published:2009/6/28 20:58:00 Author:May
In photography, a separate flash, triggered by the light of a master flash light, is often required to provide more light, fill-in shadows etc. The sensitivity of this circuit depends on the proximity of the master flash and the value of R1. Increasing R1 gives increased sensitivity. (View)
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Published:2009/6/26 4:27:00 Author:May
This simple circuit gives 15 dB gain and can be mounted on 1 in 2PCB. Coil data is given for 85 to 95 MHz. For other frequencies modify coil as required. (View)
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Published:2009/6/26 4:21:00 Author:Jessie
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Published:2009/6/26 4:17:00 Author:Jessie
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Published:2009/6/26 4:15:00 Author:Jessie
The amplifier uses a single MRF245 and provides 80 W with 9.4 dB galn across the 143 to 156 MHz band. (View)
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Published:2009/6/26 4:14:00 Author:Jessie
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Published:2009/6/26 4:13:00 Author:Jessie
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Published:2009/6/26 4:12:00 Author:Jessie
This inexpensive, easy to construct amplifier uses two MRF454 devices. Specified at 80 w power output with 5 W of input drive, 30 MHz, and 12.5 Vdc. (View)
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Published:2009/6/26 4:10:00 Author:Jessie
This 100 watt linear amplifier may be constructed using two MRF309 transistors in push-pull, requiring only 16 watts drive from 420 to 450 MHz. Operating from a 28 volt supply, eight dB of power gain is achieved alongwithexcellent practical performance featuring: maximum input SWR of 2:1, har-monic suppression more than-63 dB below 100 watts output, efficiency greater than 40%, circuit stability with a 3:1 collector mismatch at all phase angles. (View)
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Published:2009/6/26 3:51:00 Author:May
This neon-lamp driver based on the 555 T1 can be wound on an old TV flyback transformer core. (View)
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Published:2009/6/26 2:30:00 Author:May
Ferrite-rod antenna is combined with 16-inch wire rod to give cardioid radiation pattern for low-noise 160-meter antenna system. Preamp using MPF102 FETs has gain of 25 dB. L1 is 48 turns No.14 enamel spread to 4.5 inches on 0.5 inch Amidon ferrite rod 7 inches long. L2 is 6-turn link wound over center of L1.L4 and L5 are each 50 turns No.26 enamel on 780-2 powdered-iron toroid cores, with 6 turns for links L3 and L6.-D. DeMaw, Low-Noise Receiving An-tennas, QST, Dee.1977, p 36-39. (View)
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Published:2009/6/26 2:03:00 Author:May
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Published:2009/6/26 1:52:00 Author:May
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Published:2009/6/26 1:50:00 Author:May
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Published:2009/6/26 1:48:00 Author:May
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Published:2009/6/25 23:42:00 Author:May
Motor driver amplifier will deliver the rated current into the motor. Care should be taken to keep power dissipation within the permitted level. This precision speed regulation circuit employs rate feedback for constant motor current at a given input voltage. (View)
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Published:2009/6/25 23:12:00 Author:May
Shielded 5-foot square loop and single preamp pull signals out of noise when propagation conditions make other antennas unsatisfactory. Operating volt-age is supplied through coax feeder, R1 isolates signal energy from ground, and C2 keeps DC voltage out of receiver input. Nulls are off broad side of loop.-B. Boothe, Weak-Signal Recep-tion on 160-Some Antenna Notes, QST, June 1977, p 35-39. (View)
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Published:2009/6/25 23:07:00 Author:May
This minimum device circuit can be used to drive dc motors where there is some like lihood of stalling or lock up; if the motor locks, the current drive remains constant and the system does not destroy itself. (View)
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Published:2009/6/25 22:01:00 Author:May
Provides accurate clamping of baseline level of fast positive-going digital pulses with constantly changing duty cycle when capacitively coupled into level-sensitive circuits. Uses HA-2535 opamp. Diode D2 clamps negative output swing of opamp to about 0.3V, preserving amplifier recovery time in preparation for clamping next input transition, Pulse widths at input are less than 100 ns, with transition time under 15 ns and duty cycle ranging from 2 to 50%. Diodes are HP 2800 series. For clamping sine or triangle AF waves, opamp can be 741.-D. L. Quick, Clamp Speeds Restoration of AC-Coupled Base Lines, EDN Magazine, Sept. 5,1975, p 76. (View)
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Published:2009/6/25 22:43:00 Author:May
CA3080A operational transconductance amplifier uses bridge to provide automat;c temperature com-pensation of gain that is controlled by voltage between 0 and +10V applied to op amp A3. With values shown, input and output signal-handling range is ±10 V. Once balanced, circuit provides linear gain control up to four decades.-W.G.Jung, IC Op Amp Cookbook, Howard W.Sams, Indianapolis, IN, 1974, p 455-456. (View)
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