Java Circuit Simulation Workaround ▾

Due to recent changes by Oracle, java applets have become difficult to run in the browser. To mitigate the troubles, Oracle has provided the following websites to help users troubleshoot: and

Even after following the above instructions, loading applets may still show warning concerning “unsigned application” and “unknown publisher”. For Teahlab in particular, these warnings are due to the fact that we have opted not to pay a third party such as Verisign to sign our applets. Any warning that comes up when you try to run our applets should emphasize that our applets will always run with “limited access”, which is Oracle’s way of letting you know that teahlab doesn’t do anything on your computer except running the circuits you see: in other words, our applets are safe to run.


The Teahlab Team

VIDEO TUTORIALS: The Johnson Counter
by Isai Damier @isaidamier

The Johnson counter is a backbone of D-flipflops surrounded by decoding legs (AND gates). The backbone is formally known as a switch-tail ring counter. 2* flipflops = count, is a special property of the Johnson counter. To count from one to ten we would need five flipflops; from one to thirty we would need fifteen flipflops. The circuit uses one two-input AND gate per count, so that the number of AND gates in the circuit is twice the number of D-flipflops.