After my last mess-up
, I took extra care to verify circuit 1. It is correct.
The inverters are "low saturation sink drivers".
They usually drive Lamps, LED's, relays, etc.
Div1 and Div2 are driven by the CPU.
When Div1 is high (from the CPU,) the top 2k2 resistor is grounded by the driver.
When Div2 is high, the bottom 2k2 is grounded.
Some other info which might help.
The two 2k2 resistors look to be 1/8 or 1/4 watt.
The 22k and 470R resistor look to be 2 watt packages.
I might breadboard this one in a few days.
Does anyone know why the emitter is the current source ?