This circuit is from an August 1984 Radio Electronics magazine. It monitors the state of a RAM backup battery. Resistor R1 determines the battery charge.
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...