555 in EC vs real

The schematic on the left is stolen from lenzrulz. In EC the 555 nicely works with such a nonstandard wiring. But can this work *in practice*? I do not think so, because in the real 555 the discharge circuit is just a single npn transistor with its emitter connected to the "gnd" pin, and the collector connected to the "dis" pin (see the circuit on the right, with the rest of the real 555 represented by a manually controlled switch and two resistors). You can see that the voltage on the capacitor in the realistic schematic is just about the voltage drop on an open pn junction, in both positions of the switch (note also that the polarity on the transistor is reversed in this wiring!). Thus, I believe, ECs implementation of 555 must be corrected.

published 11 years ago