Only requires 2 NPN transistors and 2 resistors per switch… Perfect for driving a resistor ladder based DAC from a dip SPST switch array!
The Purpose of this is to convert SPST switches into push-pull SPDT switches so that in the ON position everything is pulled HIGH, and in the OFF position, everything is pulled LOW. This is a pretty simple and very close Rail-Rail way to do it.
The Max output will be exactly at Vcc Potential, while the minimum output will be only a few 10’s of millivolts above GND Potential! Specifically only 18.2mV above GND in this simulation. Pretty Awesome results considering the simplicity, and it makes it a perfect buffer for building a resistor ladder based DAC!
