Any high-gain Darlington transistor can be used on this touch circuit. The load can be formed by LEDs and the power supply isolated from the power grid.
We have articles on the site with the name “lamp test” for this configuration found in a Popular...
The circuit we present is suggested by Linear Technologies (www.linear.com) and makes use of an...
This current sensing circuit for applications up to 10 A has been found in a Linear Technology...