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GPS-based frequency standard 3

Published:2013/5/14 22:10:00 Author:muriel | Keyword: GPS-based frequency standard

GPS-based frequency standard 3
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GPS-based frequency standard 2

Published:2013/5/14 22:09:00 Author:muriel | Keyword: GPS-based frequency standard

GPS-based frequency standard 2
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GPS-based frequency standard

Published:2013/5/14 22:08:00 Author:muriel | Keyword: GPS-based frequency standard

GPS-based frequency standard
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Filter Circuit for the Earthworm Seismic Data Acquisition System

Published:2013/5/14 22:01:00 Author:muriel | Keyword: Filter Circuit, Earthworm Seismic Data , Acquisition System

Filter Circuit for the Earthworm Seismic Data Acquisition System
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The synthesized exciter

Published:2013/5/9 21:25:00 Author:muriel | Keyword: The synthesized exciter

The synthesized exciter
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80 Watt FM stereo broadcast transmitter

Published:2013/5/9 21:25:00 Author:muriel | Keyword: 80 Watt, FM , stereo broadcast transmitter

80 Watt FM stereo broadcast transmitter
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Small AM transmitter

Published:2013/5/9 21:24:00 Author:muriel | Keyword: Small AM transmitter

Small AM transmitter
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FTS-8 subtone encoder

Published:2013/5/9 21:19:00 Author:muriel | Keyword: FTS-8 subtone encoder

FTS-8 subtone encoder
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A 40 meter SSB QRP transceiver 2

Published:2013/5/9 21:17:00 Author:muriel | Keyword: 40 meter SSB, QRP transceiver

A 40 meter SSB QRP transceiver 2
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A 40 meter SSB QRP transceiver

Published:2013/5/9 21:16:00 Author:muriel | Keyword: 40 meter , SSB QRP transceiver

A 40 meter SSB QRP transceiver
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ULTRA LOW FREQUENCY RECEIVER

Published:2013/5/7 21:37:00 Author:muriel | Keyword: ULTRA LOW FREQUENCY RECEIVER

ULTRA LOW FREQUENCY RECEIVER
The frequency covered is from 0.1Hz to 10Hz and useful signals are received up to 16Hz. The first Op-Amp, properly shielded, must be installed close to the antenna (1-3m long) and connected to the rest of the circuit with a 5-core shielded cable. Adjust the 100k trimmer so that the DC setting at the output of the OPA124 does not change when turning the 220k sensitivity pot. A low pass filter followed by a notch filter take care of the mains induced noise. The values in brackets are good for a 60Hz mains. 1% components should be used for the 3 resistors and 3 capacitors of the notch filter. A voltage controlled oscillator gives an audible frequency that follows the input signal and it is very handy if the unit is made portable although I found that just walking around is enough to bury the signal being received. The output signal goes first to a meter and then is available for the connection to a data logger, which is an almost essential part of the receiver. Sensitivity is quite adequate: any TV set switching on in the area will be detected. There are also a host of other mysterious signals of unknown origin. The input protection diodes are special low leakage type and should not be replaced by standard diodes. These diodes can be dispensed with if the antenna is installed with care and away from strong electric fields. The diodes connected to the meter are Schottky diodes and will provide a bias against very small signals (mostly noise) which will not go through to the data logger. Pin connection for OPA124: 1 and 5: DC set, 2 and 3: inverting and non-inverting, 6: output, 8: substrate. Pin connection for LF412: 2 and 3: inverting and non-inverting, 1: output, 6 and 5: inverting and non-inverting, 7: output. (View)

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Butterworth filter has adjustable group delay

Published:2013/4/18 3:00:00 Author:muriel | Keyword: Butterworth filter, adjustable group , delay

Butterworth filter has adjustable group delay
This Sallen-Key realization of a 5.25-MHz, three-pole Butterworth filter has a gain of 2V/V and can drive 75Ω back-terminated coax with an overall gain of 1 .It can used to reconstruct component-video (Y, Pb, Pr) and RGB signals, this filter has an insertion loss greater than 20 db at 13.5 MHz and greater than 40 db at 27 MHz . Like the antialiasing filter before an ADC, this filter removes the higher frequency replicas of a signal following a DAC. To preserve quality in the video waveform, you should minimize group-delay variations in the filter and any group-delay differential between filters. (View)

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Audio / Signal Processing

Published:2013/4/18 1:58:00 Author:muriel | Keyword: Audio, Signal , Processing

Audio / Signal Processing
This Sallen-Key realization of a 5.25-MHz, three-pole Butterworth filter has a gain of 2V/V and can drive 75Ω back-terminated coax with an overall gain of 1 .It can used to reconstruct component-video (Y, Pb, Pr) and RGB signals, this filter has an insertion loss greater than 20 db at 13.5 MHz and greater than 40 db at 27 MHz . Like the antialiasing filter before an ADC, this filter removes the higher frequency replicas of a signal following a DAC. To preserve quality in the video waveform, you should minimize group-delay variations in the filter and any group-delay differential between filters.source (View)

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Sferic Signal Simulator circuit

Published:2013/3/28 4:13:00 Author:Ecco | Keyword: Sferic Signal Simulator

Sferic signal simulator is used to produce an impulse signal which simulates the waveform of a sferic, a radio atmospheric signals produced by a lightning strike. In time domain, the waveform of a sferic signal is a single high amplitude spike. When this pulse is analyzed in frequency domain, it will show a wide band spectrum ranging from few kilohertz to several tens of kilohertz. Here is the schematic diagram of the sferic signal simulator circuit: (View)

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The Wien-Bridge Oscillator Using HA2541 Op-Amp

Published:2013/3/28 3:53:00 Author:Ecco | Keyword: Wien-Bridge Oscillator , Op-Amp

The Wien-Bridge Oscillator Using HA2541 Op-Amp
A Wien-Bridge oscillator circuit can be built from HA2541 and some basic components. This circuit can generate good-quality sine wave of 40 MHz with an upper limit of 50 MHz. The R3 through R7 and D2 and D1 provide the diode limiting for this circuit. Here is the schematic diagram of this circuit: (View)