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Variable-Frequency Oscillator
Oscillator Circuits -- Main Page
 

Last Updated: November 30, 2017 07:40 AM


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

455KHz oscillator using FET & 455KHz IF transformer -  The 455-kHz oscillator circuit uses a filed-effect transistor (FET) for Q1.  The output signal is taken from the source circuit of Q1.  T1 is a 455-kHz IF transformer.  __ 

A 'Multi-Turn' Homemade Variable Tuning Capacitor -  A remarkably simple Homebrew device for tuning in your FM stations!  The Radio Shack Special project calls for a typical 6-lead variable tuning capacitor.  This item has to be mail-ordered, as Radio Shack does not carry it.  Should you have trouble finding your variable tuning capacitor for the Radio Shack Special Project, this homemade device can be substituted for it.   __ Designed by braincambre500 @ yahoo.com

A Simple Circuit VFO for 80 & 160 Meters -  This VFO is simple to build and is quite stable.  The VFO produces a two phase output (2 outputs) , making it well suited to supplying a signal to either single ended RF amplifiers, where only one__ 

Anton Chekhov -  My LO strategy involved mixing a 16.93 MHz Xtal oscillator (  Xtal Q = ~100K) with a 3.121 to 3.216 MHz Hartley L-C VFO.  I planned to use the EMRFD Figure 4.24 method to extract low noise + distortion from the Xtal oscillator and mix it with the VFO signal in a Gilbert cell mixer like the NE612. __ Contact Vasily Ivanenko

Build a PIC Controlled DDS VFO 0 to 6 MHz -  This is NOT meant as a detailed building instruction for a DDS VFO.  It is only a few fragments from my experimental work in the shack.  This is "as is" information.  It may contain errors.   However, my own prototype works very well. __ Designed by Johan Bodin, SM6LKM

Continuous Coverage V.F.O. for H.F. -  Timing and oscillator circuit diagrams / circuit schematics __ Designed by Francesco Morgantini IK3OIL

Convert any signal to exactly 50% duty cycle -  06/25/13  EDN Design Ideas:  How would you process a variable frequency signal to always maintain a 50% duty-cycle? Here's one way __ Circuit Design by Jim McLucas

DDS/PLL based VFO synthesizer -  Timing and oscillator circuit diagrams / circuit schematics __ Designed by Aleksander Stare

Direct Digital Synthesis VFO for HF Bands-based on Analog Devices AD7009 DDS -  Timing and oscillator circuit diagrams / circuit schematics __ Designed by Francesco Morgantini IK3OIL

FET Oscillators -  This circuit comes from the Progressive Communications Receiver that is in most of the recent ARRL Handbooks and the article "A Progressive Communications Receiver", by Wes Hayward and John Lawson, QST, November 1981 1.   __ Designed by Web David White, WN5Y

Frequency Reader for conversion VFOs -  If you are interested in improving the mechanical frequency reading of your home made transceiver, or if you want to equip your old RIG with a digital reader, this may be the project for you.  It is simple enough to assure a good and sure result also to beginners, and it doesn't require any microprocessor programming, in fact the only components employed are simple and conventional CMOS ICs.   __ Designed by Francesco Morgantini IK3OIL

Huff-Puff Stabilizer -  The credit for this circuit goes to Hans Summers, who developed the circuit after my suggestion that magnetic coupling would work with a frequency stabilizer.  It uses a shift register (74HC4517) as a memory for the stabilizer and provides excellent stability __ Designed by Web David White, WN5Y

K7HFD Low-Noise Oscillator -  This circuit appears in the ARRL 2000 Handbook 4.18, and in Solid State Design for the Radio Amateur, by Wes Hayward & Doug DeMaw 26.  No buffer is necessary with this VFO.  There is enough drive to go directly to a diode mixer.   __ Designed by Web David White, WN5Y

NE602 VFO Oscillator -  It's my opinion that the NE602 may have been overlooked as one of the most stable VFO oscillators around.  In the Signetics App Note "Applying the Oscillator of the NE602 in Low Power Mixer Applications", the NE602 is described as a chip with three subsystems, a Gilbert cell mixer, a buffered emitter follower oscillator, and RF current and voltage regulation __ Designed by Web David White, WN5Y

PIC16F628 controlled FLL (Frequency Locked Loop) VFO for HF -  Microcontroller based electronic circuit __ Designed by Francesco Morgantini IK3OIL

Simple Circuit Frequency Reader for conversion VFOs -  If you are interested in improving the mechanical frequency reading of your home made transceiver, or if you want to equip your old RIG with a digital reader, this may be the project for you.  It is simple enough to assure a good and sure result also to beginners, and it doesn't require any microprocessor programming, in fact the only components employed are simple and conventional CMOS ICs.   __ Designed by Francesco Morgantini IK3OIL

Variable Frequency Oscillator -  The first stage built was the VFO shown above in Figure 1.  The oscillator portion is based upon Figure 4.15 from EMRFD.  The VFO resonator tank is isolated from the JFET by tapping down as shown.  This is an outstanding VFO topology.  __ 

VFO Buffer -  In the first design of the receiver, this buffer was used with an FET VFO oscillator followed by a filter and a 2N5109 amplifier.   __ Designed by Web David White, WN5Y

VFO from 2001 ARRL Handbook 4.20 -  Schematic only __ Designed by Jim Osburn, WD9EYB

VFO/Buffer -  It's basically a standard Hartley oscillator, followed by Roy Lewallen's buffer (page 14.20 of the 2001 Handbook).  Output is +7 dBm into 50 Ohms.  Don't be tempted to add a gate diode, this circuit doesn't need it, and it will degrade the phase noise performance, according to Ulrich Rohde.  It should be suitable __ Designed by Leon Heller




Variable-Frequency Oscillator


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