Found in a 90s American documentation, this circuit is used in vehicles with contact breaker. The circuit does not provide much additional information.
In the figure we have a basic PLL circuit with the LM567 or equivalent. The circuit is from a 1977...
This circuit was found in a documentation for radio amateurs from the 70s. The integrated circuits...
The LM11 is a precision operational amplifier from National Semiconductor. The circuit was found in...