This circuit for automotive use was found in American documentation from the 90s. The circuit uses common components today. The relay is 12 V.
For measurements between 30 and 40º C this circuit was found in the documentation of 1968. The...
This circuit was found in the ON Semiconductor's Thyristor manual of the 1980s. The high quality...
Found in an old Radio Electronics, this circuit applies to frequency meters for frequencies up to 100 MHz....