For a current of 5A and a supply of 6 V this circuit was found in documentation from the 70s. Transistors admit modern equivalents. Q1 is a PUT uncommon today.
Found in a 1960 General Electric documentation, this crowbar circuit blows the fuse in case of...
This circuit was originally designed for testing crystals used in color televisions, but it works...
This bridge-biased transistor test circuit measures gain in the range 0 to 300. Circuit is from...