We found this code key or coded keyboard in a publication from the 90s. The circuit uses components that are still common today and is powered by a 12 V voltage according to the relay used.
This precision speed control was obtained in an Electronic Design from the 90's. The output final...
This amplifier for old record players has RIAA correction and was found in documentation from the...
We found this configuration with a logic circuit that is now uncommon in an 80's documentation. The circuit...