The purpose of this circuit is only to increase the input resistance of a multimeter, since there is no voltage gain. The batteries are 9 V and operational equivalents can be used.
Using a 4046 PLL this circuit recognizes a 1.6 to 1.8 kHz tone by driving an output LED. The...
This battery charger circuit was found in ancient American documentation. The components are...
This circuit is of great use today, when solar energy is becoming increasingly important. The...