Converters: Voltage to Frequency, Page 2
Voltage Controlled Oscillators (VCO)
VCO; Voltage to Frequency Converters:  #'s - A     B - K     L - U    V - Z
Last Updated on: Friday, July 18, 2008 11:32 AM
 

Circuits Designed by Dave Johnson, P.E. :

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.

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.  (added 12/04)

AIR TRANSPARENCY MONITOR, XENON FLASH RECEIVER This is Page 2 of the receiver circuit

CMOS SCHMITT TRIGGER IC MAKES VCO By changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a range of 50:1.  A 74HCU04 inverter is used at the output of the 4584 to maintain a constant TTL logic level signal.

Light to Frequency Converter This circuit uses a CMOS version of the classic 555 timer, to form a light intensity to frequency converter.  A small PIN photo diode is used as the light detector.  The pulses produced are short, so in some applications you may want to stretch them or feed them through a flip/flop to produce a square wave signal.  Although the circuit shown is designed for a 5v supply, it could operate from almost any voltage from 3v to 15v.

VOLTAGE TO FREQUENCY CONVERTER + 1uS LED PULSE DRIVER  This circuit receives the signal from the above amplifier and launches powerful 1uS infrared light pulses from a low cost LED that are frequency modulated by the audio information. The 10KHz center frequency of the pulse stream is low enough so a standard infrared LED can emit ten times more light than conventional long pulse techniques. The circuit is described in more detail in the transmitter section of my Handbook of Optical Through the Air Communications.

Circuit Ideas for IC Converters:  AN-343 Analog Devices Application Notes  (app note added 2/06)

CMOS Inverter VCO Tunes Octave to UHF:  11/19/98 EDN-Design Ideas / (added 3/03)  

Designs for High Frequency Voltage-To-Frequency Converters:  AN14 Linear Technology A variety of high performance V/F circuits is presented. Included are a 1Hz to 100MHz design, a quartz-stabilized type and a 0.0007% linear unit. Other circuits feature 1.5V operation, sine wave output an nonlinear transfer functions. A separate section examines the trade-offs and advantages of various approaches to V/F conversion.

DPP Adds Versatility to VFC:  11/14/02 EDN Design Ideas  /  (added 1/05)  The basic VFC (voltage-to-frequency converter) in Figure 1 comprises an integrator (IC1) and a Schmitt-trigger circuit (IC2). The integrator converts the dc input voltage, VIN , to a linear voltage ramp, and the Schmitt trigger sets the limits of the integrator's output voltage. Feedback around both circuits provides the condition for oscillation....

Ground Rules for High Speed Circuits:  AN-214 Analog Devices Application Notes  (app note added 2/06)  Layout and Wiring Are Critical in Video Converter Circuits.

Inverters Form Three Phase VCO:  08/02/01 EDN Design Ideas  /  (added 1/05)  You sometimes need an inexpensive VCO that can produce evenly spaced three-phase outputs over a wide frequency range. You could use tracking all-phase filters with only one oscillator, but this technique is difficult to implement and offers limited range. Other methods, such as using a DSP, are feasible, but they're complex and expensive....

Inverting Latches Make Simple VCO:  06/19/97 EDN-Design Ideas / (added 3/03)