Found in a 1924 documentation, this circuit is powered by 3 batteries, two of which are high voltage. The output is a high impedance headphone jack.
This power supply with transistor regulation was obtained in a 1995 documentation. The power...
This two-station intercom was found in documentation from 1966. R4 should be experimentally...
We found this circuit in a publication from 1966. The components are from the period. Complete...