The integrated circuit used in this application is uncommon today. The circuit is from American documentation from the 1980s. It can be changed to use more modern equivalent components.
The figure shows how to measure current with a 3 ½ digit 7107 meter described in Electronics Now...
I found this electronic organ in magazine published in 1976 from my vast collection of foreign...
The presented circuit uses the National Semiconductor's LM3909, an oscillator that operates with...