This circuit shows how to make an adaptation on an AM receiver to receive CW and SSB signals. The circuit is from an 80's documentation. The diode is commonly used.
This alarm circuit is from a 1987 publication, however the components used are still modern. The...
In the figure we have a configuration that allows to test NPN transistors and with the addition of a...
We find this current meter circuit from 0 nA to 200 nA in a Linear Technology application manual....