This circuit was found in an old Electronic Design. It makes use of sidacs and operational not very common today. The power supply must be symmetrical.
November 2016 - Mouser Electronics has in stock the new TC9400, Voltage-to-Frequency Converter...
This circuit can work with both TTL and CMOS circuits depending on the power supply. The circuit is...
This 1.6 to 20 V power supply, with a maximum current of 3.5 A and protection against short...