This circuit is from the 1990 Motorola Linear Databook, which can be developed with more modern equivalent operating systems. The 1 uF capacitor should be of good quality polyester with small leaks
This circuit source a voltage proportional to the number of the input pulses. The circuit has a...
This circuit is from a 90's Radio Electronics. The circuit operates accurately up to about 15 kHz...
This is a circuit suggested by Linear Technology in a 1980s documentation. The integrated circuit is from...