555 voltage-to-time converter

http://www.edn.com/article/CA61850.html

This circuit is also Crossed to: Monostable Circuits , , Timer Circuits

The circuit in Figure 1 is a simple, low-cost voltage-to-time converter using the ubiquitous 555 timer chip. You can use the IC`s monostable multivibrator as a voltage-to-time converter by connecting the analog-voltage input to the charging resistor, R, instead of connecting R to VCC. With this modification, the timer chip`s output-timing cycle, tP, is proportional to the input voltage, VIN.

When you apply an input voltage, the voltage across capacitor C charges exponentially according to the formula VC=VIN(1et/RC), where RC is the time constant of the circuit, with C in farads and R in ohms. During one time constant, the voltage acro http://www.edn.com/article/CA61850.html