I had old broken toy car. I wanted to use it's RC module to switch 12V fan. I measured original circuit, found the output, saw 3V there (fig. A). Then I assumed that RC module switches the 3V and designed my circuit accordingly (fig. B). It was always on. Only then I start analyzing it more deeply and to my surprise I found out that RC module output is permanently connected to 3V and only switches second output to the ground (fig. C).
I used NPN transistor in TO220 package from old PC power supply, as that was only power transistor I had. Is it possible to modify this circuit so that switching to the ground would switch it?