Thyristors can look like transistors

[b]with a thyristor, which looks like a transistor, you can create a very simple latching circuit without the use of an on switch. A momentary switch can be used to briefly short the thyristor, turning it off. Fascinating things they are. Momentary switches will work to turn it on, and it will stay on until you shut it off. Think of it as a non mechanical latching switch![/b]