4QD-TEC: Electronics Circuits Reference Archive Welcome to 4QD-TEC - 'The Electronics Club' Index for this page. This page contains the main index to the electronics section of this site, with certain other general information which you may need. Site Index of electronic circuits. 4QD TEC Introduction To Join 4QD-TEC use the button at head or foot of any free page. Members private data area if you have a password. Transistors or ICs? Transistor types Educational Resource Problems and queries Fut ...