DC to AC

Trying to run a simulation of a DC to AC inverter but i cant get circuit lab to run it. It tells me I'm not getting any voltage on the secondary side of the transformer. any ideas? the project is biased on what i found here https://www.electronicshub.org/12v-dc-220v-ac-converter-circuit/

by syotos
October 27, 2022

McAfee does not allow me to see the site you supplied as reference.

Many flaws in the circuit.

First, note that the circuit is symmetric (fold it through a vertical) while you want an anti-symmetric result (the oscillation). In real life, the oscillation may start because of some difference (in the transistors, resistors, capacitors), but numerically, the symmetry is too strong, and the oscillation does not start. We MUST include a "light" numerical difference (in the resistor) to break the symmetry. How much? that depends on each numerical simulator.

Second, the wiring is wrong. Each capacitor has to be tied to each of its ends to one of the resistors. Right now, each cap bypasses the connection, that it should NOT.

Third, the DC voltage should be high enough to satisfy the threshold of Vbe for the BJTs and ... Vgs(th) for the NMOS. One volt is clearly not enough.

Fourth, the NMOS. A transistor is like something which squeezes a water hose, to block the flow, or to relax the sqeeze and allows the flow to run through a water hose. BUT the FLOWS has to be possible. Right now, for the NMOS, their GATE pin is the squeezer, their source pin is connected to the ground, nice, BUT their drain pin, which should receive the flow, is NOT CONNECTED to ANY flow. You may have a better result by removing them completely and connecting the transfo directly to the intersection point of the cap-resistor-BJT_Collector.

There may be other problems. While that oscillator is often used for demonstration purposes, it is not often used for practical application. Among other problems, is to start the oscillation, even in the real world, when the "load" is something else than a LED. Well, if it works for you, fine.

by vanderghast
October 29, 2022

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