This simple power supply, which is equivalent to 2 AAA or AA batteries, was found in an Elektor from the 90's. The transformer has a 4.5 V secondary with a current of 50 mA or more.
This TTL decoder circuit for PC ports was found in a document from 1992. The power supply can be...
The presented circuit is suggested by Texas Instruments (www.ti.com) in its Application Report...
We found this configuration in an early 1977 publication. The PNP transistor may be the BC558 and...