This simple general-purpose transistor mixer was taken from an article in Electronics Now magazine in March 1994. You can choose a low-noise transistor such as the BC549.
In the figure we have a very simple trigger circuit for an SCR that powers a 12 V lamp whose...
With the use of precision resistors and capacitors, this circuit with programmable unijunction transistor...
This 15 W power stage was found in Radio Electronics magazine from August 1959. The transistors are the...