The configuration shown was found in an old Poptronics but can be easily assembled using a common calculator photocell. The relay is according to the supply voltage.
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...