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Oscillators:  Voltage Controlled (VCO)   Page 1
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Oscillator Circuits -- Main Page
Last Updated on: Tuesday, April 01, 2014 04:29 AM


Circuits Designed by Dave Johnson, P.E. :
  • 40KHz Voltage to Frequency Converter
    This circuit was designed to frequency modulate a 40KHz carrier, using human voice frequencies.  A common flip/flop is used at the core of the circuit.
  • 200MHz - 400MHz VOLTAGE controlled OSCILLATOR
    If you need a clean emitter coupled logic (ECL) type signal between 200MHz and 400MHz this circuit works fine. It uses four voltage controlled capacitors to change the frequency.

  • Air Transparency Monitor, Xenon Flash Receiver
    I designed this circuit many years ago to monitor the quality of a mile long column of air for future optical communications experiments. The transmitter system (circuit 72 below) uses a powerful xenon flash in conjunction with a large 12 inch fresnel lens at the transmitter end and a matching 12 inch lens with a PIN photo diode at the receiver. The receiver system was connected to a weather station and a computer to collect the changes in intensity of the light flashes under different weather conditions. It has the potential for a 30+ mile range. I have also used this system to conduct cloud bounce experiments.

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:
0.02% V/F converter consumes only 26 A -  07/04/96 EDN-Design Ideas....Figure 1  shows a voltage-to-frequency (V/F] converter that produces a 0- to 10-kHz output for an input range of 0 to 5V. Linearity of the converter is 0.02%, and gain drift is 60 ppm/8C. The maximum current consumption is only 26 �A, 100 times lower than currently available units. To understand the circuit's operation, assume.... [Design Idea by Jim Williams, Linear Technology, Milpitas, CA]
10 Khz VFC uses Charge Pump Variation -  04/09/98 EDN-Design Ideas....A diode-capacitor charge pump is the starting point for many voltage-to-frequency-converter (VFC] designs. The circuit in Figure 1 uses a variation on that classic theme to achieve linearity less than 0.05%, micropower operation of approximately 10-�A total draw from a 5 to 36V rail, and bipolar-input capability....several circuits included, scroll the find this one.... [Design Idea by Stephen Woodward, University of North Carolina, Chapel Hill, NC]

200mhz-400mhz Voltage Controlled Oscillator (VCO) -  If you need a clean emitter coupled logic (ECL) type signal between 200MHz and 400MHz this circuit works fine. It uses four voltage controlled capacitors to change the frequency.... [Designed by David A. Johnson]
40kHz Voltage to Frequency Converter -  This circuit was designed to frequency modulate a 40KHz carrier,. [Designed by David A. Johnson]
555 VCO -  By adjusting the voltage on pin 5, (the CONTROL pin) the frequency of the oscillator can be adjusted quite considerably.
8 pin C forms one-chip Programmable VCO  -  09/24/98 EDN-Design Ideas....The circuit in Figure 1 uses a Microchip 8-pin C (PIC12C671]as a voltage-controlled oscillator (VCO]. Because  PIC12C671 has an internal 4-MHz oscillator, four-channel 8-bit A/D converters, and built-in power-reset circuitry, you need no external components to configure  VCO.... [Design Idea by Yongping Xia, Teldata Inc, Los Angeles, CA]
90 MHz voltage controlled oscillator for FM Band  -  Notice the abundance of 2N4401, 1 k resistors and 330 Ohm resistors? That's because I have a lot of each. 2N4401's weren't intended to be used as varactors, but they work just fine. Don't be afraid to xperiment with the parts you have on hand. Build this on a ground plane board. Layout is important..(schematic / circuit added 6/07)
Air Transparency Monitor, pg 1 -  I designed this circuit many years ago to monitor the quality of a mile long column of air for future optical communications experiments. The transmitter system (circuit 72 below) uses a powerful xenon flash in conjunction with a large 12 inch fresnel lens at the transmitter end and a matching 12 inch lens with a PIN photo diode at the receiver. The receiver system was connected to a weather station and a computer to collect the changes in intensity of the light flashes under different weather conditions. It has the potential for a 30+ mile range. I have also used this system to conduct cloud bounce experiments.... [Designed by David A. Johnson]
Air Transparency Monitor, pg 2 -  This is Page 2 of the air transparency monitor receiver circuit.... [Designed by David A. Johnson]
AN-1174: Startup Time[comma] Profile Measurement of PLL VCOs & Crystal Oscillators -  National Semiconductor Application Note....[App Note]
AN-213: Low Cost, Two-Chip, Voltage-Controlled Amplifier & Video Switch -  AN-213 Analog Devices Application Notes....[App Note]
AN-45-001  Automated load measurement of VCO's -  Application Note MiniCircuits.com  (app note added 2/06)
AN-45-002  Line Stretchers Ease VCO Load-Pull Testing -  Application Note MiniCircuits.com  (app note added 2/06)
AN-95-003  Glossary of VCO terms -  Application Note MiniCircuits.com  (app note added 2/06)
AN-95-004  Wide Modulation Bandwidth Measurements -  Application Note MiniCircuits.com  (app note added 2/06)
AN-95-005  How VCO Parameters Affect Each Other -  Application Note MiniCircuits.com  (app note added 2/06)
AN-95-006  Optimizing VCO/PLL Evaluations & PLL Synthesizer Designs -  Application Note MiniCircuits.com  (app note added 2/06)
Analog voltage controls digital potentiometer -  20-Mar-08 Issue of EDN  A microcontroller with an internal ADC controls a digital potentiometer via an I2C interface.... [Design Idea by Hrishikesh Shinde, Maxim Integrated Products, Dallas, TX]
Arduino LFO Waveform Generator -  This project uses an Arduino microprocessor and a DAC0808 8 bit parallel DAC to produce arbitrary low frequency oscillator (LFO) waveforms. These waveforms are useful for driving a tremolo/vibrato circuit in a guitar amplifier such as the Lil Tiger or a phaser effect such as the Liquidator.... [G. Forrest Cook]
Automated load measurement of VCO's -  AN-45-001 Application Note MiniCircuits.com  (app note added 08/08/08)

Oscillators:  Voltage Controlled (VCO)  -  #'s - A      B - H       I - S       T - Z
Oscillator Circuits -- Main Page


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