Dave's Circuits:  Frequency to Voltage     Period to Voltage     Sine to Square Wave      Voltage Converters     Voltage to Frequency      DC to DC Power Supplies  
High Voltage Power Supplies   Switchmode Power Supplies  Voltage Controlled Oscillators

• 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.

• 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.

• 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.

• Air Transparency Monitor, Xenon Flash Receiver, Page 2
  This is Page 2 of the receiver circuit Air Transparency Monitor, Xenon Flash Receiver

• 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.