This crystal configuration can be made with triggers of any logic. The frequency is given by the formula next to the diagram. This setting is specifically for TTL.
This fast converter using operational was found in a 70s American documentation. The circuit can be...
This circuit uses two sensors that are placed at the intersection of a miniature railroad, causing the LED...
This RF wattmeter was found in an American 1980s documentation. The components are common and the...