Oscillator Circuit

“UNIVERSAL”VFO

Published:2009/6/23 2:30:00 Author:May

Figure 63-16A shows the basic circuit for the VFO, except for the tuning circuits (which are shown in Fig. 63-16B). Transistor Q1 is a junction field-effect transistor (JFET) oscillator stage. The device to use at Q1 includes MPF-102, 2N4416, and the replacement devices from the popular lines of service parts e.g., ECG and NTE).Two different oscillator configurations can be accommodated by this design (i.e., both Clapp and Colpitts oscillators can be built). Both oscillators are the same from point A in Fig. 63-16C forward, and both depend on a capacitor voltage-divider feedback network. The Clapp oscillator (Fig. 63-16A) is series-tuned and the Colpitts oscillator is parallel-tuned (Fig. 63-16B).The dc voltage supplied to the oscillator transistor (Q1) is voltage-regulated. The voltage regu-lator can be any 78Lxx series from 78LO5 to 78LO9.   (View)

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DARLINGTON_TRANSISTOR_OSCILLATOR

Published:2009/6/23 2:23:00 Author:May

This oscillator uses a very large capacitance-to-inductance ratio. L1 is a one-tum coil consisting of a loop of #12 wire 12 in diameter. This circuit is useful for metal detectors, etc., where a loop antenna is used.   (View)

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GROUNDED_BASE_TUNED_COLLECTOR_OSCILLATOR_FOR_AM_BROADCAST_BAND

Published:2009/6/23 2:20:00 Author:May

  (View)

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VLF_LC_OSCILLATOR

Published:2009/6/23 2:19:00 Author:May

The VLF oscillator uses a large toroid coil as the frequency-determining component and a 2N5485 FET as the active device. R3 is used as a feedback control and also by running the circuit with slightly less feedback than needed for oscillation, can serve as a regenerative amplifier or detector.   (View)

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MODIFIED_HARTLEY_OSCILLATOR

Published:2009/6/23 2:18:00 Author:May

This oscillator uses a tapped coil in the collector circuit, with the tap grounded for the signal. L1 and L2 are coupled inductively and typically have a 3:1 turn ratio, and generally are sections of one entire winding.   (View)

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455_kHz_OSCILLATOR

Published:2009/6/23 2:17:00 Author:May

The 455-kHz oscillator circuit uses a field-effect transistor (FET)for Q1. The output signal is taken from the source circuit of Q1. T1 is a 455-kHz IF transformer.   (View)

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BUTLER_OSCILLATOR_CIRCUIT

Published:2009/6/23 2:15:00 Author:May

This circuit uses an overtone crystal in a Butler oscillator. L1 is approximately 1300μH, and the crystal frequency should be from 20 to 50 MHz.   (View)

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BEAT_FREQUENCY_OSCILLATOR_FOR_AM／SW_RADIOS

Published:2009/6/23 2:14:00 Author:May

This BFO can be added to inexpensive AM/SW receivers to enable reception of CW signals. Output couples to base of last IF stage. T1 is any 455-kHz IF transformer. The BFO switch should be a DPDT type (as needed), and the radio AGC circuit will probably have to be disabled for CW reception.   (View)

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REMOTE_OSCILLATOR_HIGH_FREQUENCY_VFO

Published:2009/6/23 2:12:00 Author:May

A remote VFO is sometimes used to control a transmitter or receiver. The circuit shown uses an MPF102 FET and is conyolled by a dc voltageat J3. The table shows values for L1 for various bands from 30 to 10 meters. U1 senres as a buffer amplifier.   (View)

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REINARTZ_OSCILLATOR

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

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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AM_OSCILLATOR_FOR_WIRELESS_MICROPHONES

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

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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JFET_VARIABLE_FREQUENCY_OSCILLATOR

Published:2009/6/23 2:01:00 Author:May

This simple JFET-based variable-frequency oscillator can be used in receiver and transmitter circuits.   (View)

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FREQUENCY_MODULATED_OSCILLATOR

Published:2009/6/23 2:00:00 Author:May

This circuit can be used for FM wireless audio, microphone, and part-15 applications where a stable frequency modulated oscillator is needed. LT can be varied to cover 75 to 150 MHz, as needed.   (View)

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COLPITTS_OSCILLATOR

Published:2009/6/23 1:58:00 Author:May

Here: L1≈7μH/f, C1≈C2≈C3≈2400pF/f, where.f is in MHz. In this circuit, the oscillator is free-running.   (View)

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CRYSTAL_OSCILLATOR_Ⅲ_

Published:2009/6/23 1:58:00 Author:May

These circuits are for use with a crystal-controlled LO usmg the NE602 C1，C2，and C3 arefor crystals in the 5-MHz region and are approx⒈mately chosen from C3 is for fine tuning the crystal frequency and will be 20 to 50 pF typically．   (View)

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FREQUENCY_DOUBLER_AND_CRYSTAL_OSCILLATOR

Published:2009/6/23 1:56:00 Author:May

This frequency doubler produces a sine wave at twice the frequency of XTALl. Notice that the output is taken only from OUT B (pin 5), while OUT A (pin 4) is left open.   (View)

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DIGITALLY_CONTROLLED_SQUARE_WAVE_OSCILLATOR

Published:2009/6/23 1:54:00 Author:May

IC1 LM3909 LED flasher/oscillator IC2 CD4066 quad bilateral switch C1，C2 0.1-μF capacitorC3 0.033-μF capacitorC4 0.047-μF capacitor C5，C6 0.1-μF capacitorR1 2.2-kΩ, 1/4-W 5% resistorR2 10-kΩ potentiometerR3 2.7-kΩ, 1/4-W 5% resistorR4 470-Ω, 1/4-W 5% resistor   (View)

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CRYSTAL_OSCILLATOR_WITH_ADJUSTABLE_FREQUENCY

Published:2009/6/23 1:53:00 Author:May

In this crystal oscillator circuit, C3 adjusts the frequency of the oscillator for exact netting. The crystal is a fundamental type. C1= 100 pF and C2 = 1000 pF are typicd.   (View)

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dc_SWITCHED_CRYSTAL_OSCILLATOR

Published:2009/6/23 1:53:00 Author:May

This circuit is useful where several different crystal frequencies must be switched using a dc source. The values shown are typical for 40- to 60-MHz third-overtone crystals. Limitation on number of crystals depends on PIN diode capacitance and layout factors, but up to 5 or 10 crystals is possible.   (View)

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CRYSTAL_OSCILLATOR_Ⅱ

Published:2009/6/23 1:51:00 Author:May

An NE602 can be used as a crystal oscillator.   (View)

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