We found this circuit in a 1991 Hobbyst Electronics. The circuit makes use of an unusual transducer today. It is a piezoelectric buzzer that can eventually be replaced by an equivalent configuration.
The integrated circuit of this 80's project is not common today. This is the HA2530 which must be...
We find the original circuit in a technical publication of 1978. Changing the components, such as...
This circuit can be used as a shield for microcontrollers. The circuit is from American...