Found in American documentation from the 90's, this circuit applies to other operational amplifiers. The frequency can be changed by changing the components.
This heartbeat sensor circuit was found in the July 1992 issue of Radio Electronics magazine. The...
We found this circuit in the 1982 SGS integrated circuit manual. The integrated circuit is not...
This TTL pulse stretcher or stretcher was found in a 90's EDN. The time constant R x C1 determines...