Source
http://www.bowdenshobbycircuits.info/page9.htm
Set/Reset Flip Flop
This is an example of a set/reset flip flop using discrete components. When power is applied, only one of the transistors will conduct causing the other to remain off. The conducting transistor can be turned off by grounding it's base through the push button which causes the collector voltage to rise and turn on the opposite transistor.
