This excellent tube preamplifier was found in Radio Electronics magazine from July 1958. The power supply was not included. The circuit has several inputs.
We found this circuit in an English magazine from 1976. The magazine no longer exists, but just...
The figure shows a simple way to have emergency power for a 9 V circuit powered by a source. If...
Found in an Electronic Design from the 90's, this circuit supplies voltages according to the...