We found this circuit in an American documentation from the 1990s. The circuit is based on the LM3909, a low power oscillator from National Semiconductor.
The more sensitive the instrument used the better the sensitivity of the indicated meter. We...
Based on the 4017 integrated circuit, this circuit of a European 303 Circuits from the 90s,...
The integrated circuit used in this project is unusual and it includes internal transistors that...