Circuit Diagram

REINARTZ_OSCILLATOR

Published:2009/6/23 2:09:00 Author:Jessie

This oscillator uses mauctivity coupled emitter and collector windings to its main tank circuit.Take care so that L1 and L2 are not coupled to each other, otherwise this circuit is susceptible to parasitic at other frequencies.Typically ,L1 has 5 to 10 times the number of turns that L2 has.L1，L2，L3 are woundon same coil form. This oscillator is more suited to lower frequencies，≤10 MHz.   (View)

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AUDIO_MIXER

Published:2009/6/23 1:49:00 Author:May

The 741 op amp is used as a summing amplifier to combine several audio inputs. Overall gain is set by Rf.   (View)

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PSEUDO_RANDOM_BIT_SEQUENCE_GENERATOR

Published:2009/6/23 2:09:00 Author:Jessie

In this circuit, an additional exclusive-OR gate is connected after the modulo-2 feedback, with C1 and R2 applying the supply turn-on ramp into the feedback loop. This provides sufficient transient signal so that the PRBS generator can self-start a power-up. A shift-register length n of 10 is shown with feedback at stages 3 and 10, providing true and inverted maximal length sequence outputs. This technique applies an input directly to the feedback loop. Therefore, it's considered more reliable than applying an RC configuratior) to the shift-register reset input to create a random turnon state.   (View)

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FET_VXO_CIRCUIT

Published:2009/6/23 1:49:00 Author:May

An MPF 102 is used in a Colpitts-type oscilla-tor in order to pull the crystal frequency slightly.   (View)

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dc_OUTPUT_CHOPPER

Published:2009/6/23 1:49:00 Author:May

Any dc voltage source in the 2- to 15-V range can be chopped into a unipolar square wave that has a peak amplitude nearly equal to the dc source voltage with circuit (lightly loaded CMOS will swing within a few millivolts of each rail at low frequencies). Depending on the actual voltage of the supply, the programmable-unij unction-transist or (PUT) relaxation oscillator produces 2000-Hz trigger pulses. These pulses operate the cascaded 74C107 flip-flop, producing a square wave.   (View)

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PROGRAMMABLE_GAIN_NONINVERTINGAMPLIFIER_WITH_SELECTABLE_INPUTS

Published:2009/6/23 2:08:00 Author:Jessie

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ABSOLUTE_VALUE_AMPLIFIER

Published:2009/6/23 2:07:00 Author:Jessie

The circuit generates a positive output voltage for either polarity of input. For positive signals, it acts as a noninverting amplifier and effective. The accuracy is poor for input voltages under 1 V, but for less stringernt applications, it can ve effective.   (View)

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AM_OSCILLATOR_FOR_WIRELESS_MICROPHONES

Published:2009/6/23 2:05:00 Author:Jessie

This circuit will generate an AM-modulated signal in the AM broadcast band that can be picked up on a receiver.About 2V of audio input will produce about 30% modulation of the oscillator signal.An old AM broadcast oscillator coil or other two-winding coil with about a 10:1 turn ratio and about 50 to 150 μH inductance can be used for T1.   (View)

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CRYSTAL_OSCILLATOR_I

Published:2009/6/23 1:49:00 Author:May

In this circuit, series-resonant crystal XTAL1 is used as a frequency-determining element.XTAL1 is between 0.1 to 10 MHz.   (View)

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VOLTAGE_CONTROLLED_AMPLIFIER

Published:2009/6/23 2:04:00 Author:Jessie

This circuit is basically an op amp with an extra input at pin 5. A current Ltac is injected into this input and this controls the gain of the device linerly. Thus by inserting an audio signal (±10 mV) between pin 2 and 3 and by controlling the current on pin 5, the level of the signal output (pin 6) is controlled.   (View)

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PRECISION_PROCESS_CONTROL_INTERFACE

Published:2009/6/23 2:03:00 Author:Jessie

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QUADRATURE_WAVE_OSCILLATOR

Published:2009/6/23 1:49:00 Author:May

By using a high-frequency quad current-feedback amplifier (the HA5025) as an RC oscillator, four quadrature sine waves can be generated. The HA5025's four separate amplifiers generate the sine waves, and the quad NAND gate, U2, is biased at its threshold, so it acts as a sine-wave to square-wave converter when the she waves are ac coupled into its input.   (View)

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1_dB_PAD

Published:2009/6/23 2:03:00 Author:Jessie

The 1-dB pad is useful as a termination in RF work to limit possible mismatch range between system blocks, etc.   (View)

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SUBAUDIBLE_TONE_ENCODER

Published:2009/6/23 1:48:00 Author:May

This twin-T oscillator produces six preset subaudible tones from 93 to 170 Hz in three ranges.   (View)

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FET_QUARTZ_CRYSTAL_OSCILLATOR

Published:2009/6/23 1:48:00 Author:May

This oscillator uses an MPF102 JFET as an active element.   (View)

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SWR_WARNING_INDICATOR

Published:2009/6/23 1:47:00 Author:May

Op amp with dc input from SWR metercan be adjusted to preset the SWR reading at which the LED lights.   (View)

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CODE_PRACTICE_OSCILLATOR_1

Published:2009/6/23 1:46:00 Author:May

Oscillator, works with 2 to 12 Vdc (but 9 to 12 volts gives best volume and clean keying). R1 can be replaced with a 500 K pot and the circuit wili sweep the entire audio frequency range.   (View)

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REMOTE_RE_CURRENT_READOUT

Published:2009/6/23 1:45:00 Author:May

A suitable pilot lamp is illuminated by a small sample of rf and energizes an inexpensive solar cell; the dc current generated by the cell is a measure of relative rf power, and may be routed to a low-current meter located at any convenient point. A sensitive, low-current pilot lamp is desirable to cause minimum dis-turbance to normal rf circuit conditions. The number 48 or 49, 60 mA lamp is suitable for use with transmitters above 1-watt output.   (View)

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SELF_POWERED_CW_MONITOR

Published:2009/6/23 1:44:00 Author:May

Position L near the transmitter output tank to hear the key－down tone。Then tape the coil In place. C＝.047μF，R＝8.2 K，Q＝HEP 253(or equal)，T＝500：500 ohm center tapped transformer. L = 2 to 6 turns on 1/2'' coil from.   (View)

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OUTPUT_TO_CURRENT_CONVERTER

Published:2009/6/23 1:44:00 Author:May

Occasionally, it is preferable to generate a cur-rent, rather than a voltage, output into the load.The availability of differential inputs aJlows this to be accomplished in any of the four basic modes.If the output is to integrated, ZL can be sim-ple high-quality capacitor, unloaded by an op amp connected as a high-impedance follower.Note that, if desired, one side of a rest switch can be grounded.The compliance constraint for this configura-tion, where VL is an arbitrary common-mode po-tential, is: |VL+IOUT(ZL+RS)|≤12V   (View)

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