Basic question, I think. I'm having trouble understanding how this circuit is operational (with reference to the grounds).
There is an external voltage source applied (bottom right) where the green, external GND (let's call it GND-in) is connected directly to the GND that connects to the parallel port (call it GND-p).
http://www.captain.at/electronics/atmel-programmer/atmega16-programmer.png
Is voltage between GND-in and GND-p zero, always? Could GND-in be lower than GND-p, making a short between the two and frying my computer's parallel port?
Thanks. Still on the steep part of the learning curve, I guess
There is an external voltage source applied (bottom right) where the green, external GND (let's call it GND-in) is connected directly to the GND that connects to the parallel port (call it GND-p).
http://www.captain.at/electronics/atmel-programmer/atmega16-programmer.png
Is voltage between GND-in and GND-p zero, always? Could GND-in be lower than GND-p, making a short between the two and frying my computer's parallel port?
Thanks. Still on the steep part of the learning curve, I guess