We found this circuit in a 1965 Electronic Design. Transistors are still common but admit equivalents for some of them. The circuit drains a current of only 4 mA.
Texas Instruments LMV3xxA operational amplifiers are low voltage types (2.5 to 5.5 V). In the...
This circuit was found in old documentation, but the transistor may be the modern equivalent BC547....
This circuit can be used in panel signaling with common incandescent lamp. The lamp will flash at a...