This simple Bargraph photometer with 4 LEDs was found in a 1997 documentation. The scale is adjusted in a trimpot and the sensor can be any common LDR. Power can be supplied by cells or battery.
We can implement this filter with more modern equivalent operational amplifiers, since the LM110 is...
This stethoscope or amplifier for hearing aid using a crystal headset and microphone was found in a...
The normal use of a 4520 as a divide-by-16 counter is shown in Figure bellow. In the normal...