mystery

ZXNet echo conference «hardware.zx»

From Kirill Frolov To All 8 September 2001

Press RESET immediately, All! There is a diagram: KT315 and KT361 two transistors, collectors together, emitters on GND and 5 volts. The bases are connected together through ~1k resistors and ~100Khz meander is applied there. An electrolytic is connected to the collectors capacitor ~10 µF, after it there are two diodes and another capacitor at the output. This is to make a negative voltage from +5v - I hope the circuit imagine. So at the output (and there is a load - a microcircuit) there is a negative voltage of -4.5 volts. I forgot to say that diodes used type KD522. So the question is - how do you get -4.5 volts at the output when powered? +5.09 volts? If you calculate the voltage drop across 2 diodes and 2 THIS CAN'T HAPPEN WITH TRANSISTORS!