Looking for input on basic schematic for 12vdc to 120vac inverter

[Jfanth]

Apologize in advanced if this is the wrong thread, point me in the right direction if so.
I have looked at other threads and see somewhat similar to what I’m looking to do but not quite.
I have a 115v 24/22w @50/60hz circuit test fan I’m wanting to run using 12vdc. I guess my question is are there any schematics I haven’t seen in order to this or what’s the easiest route as far as components go. I have all the stuff to make my own pcb I’m just a novice when it comes to schematics and which components are best. Thanks

 

[BradtheRad]

You wish to step-up voltage 10X. It can be done in one jump, or by cascading two or more jumps, using the same or different methods.
Power inverters you've seen probably use one of below methods:

* Chop 12V through H-bridge, feed to step-up transformer to obtain 120VAC square waves.

* inductive boost converter steps up to 120V, then chop through H-bridge.

* capacitive voltage multiplier steps up 10X. Then chop through H-bridge.

If you want sinewave output that requires more effort.

At 12V 22W your system draws 2 Amperes average.

 

[Jfanth]

You wish to step-up voltage 10X. It can be done in one jump, or by cascading two or more jumps, using the same or different methods.
Power inverters you've seen probably use one of below methods:

* Chop 12V through H-bridge, feed to step-up transformer to obtain 120VAC square waves.

* inductive boost converter steps up to 120V, then chop through H-bridge.

* capacitive voltage multiplier steps up 10X. Then chop through H-bridge.

If you want sinewave output that requires more effort.

At 12V 22W your system draws 2 Amperes average.

Correct
So which would be my best option in order to run a small circuit test fan? I’m using it in order to keep a compressor cooler as it heats up fairly quick.
All the diagrams I’ve found are all 220v can you point me in the direction of where to find one for 120v

 

[BradtheRad]

It is difficult to wind your own inductors/ transformers. An alternative is the capacitive multiplier. Cockcroft-Walton style is popular because no component is exposed to greater than supply voltage 12V. Behavior is predictable and output voltage never soars out of control regardless if load is light or absent.

Assemble a great many capacitors and diodes so you have two X10 step-up multipliers, one positive, one negative. At the output stage build a half-bridge to turn 120VDC into AC square waves to your load (fan).
At the input stage build a full H-bridge to chop your 12VDC supply into AC.

 

[crutschow]

An inverter circuit such as below, with a 120V-24V center-tapped transformer such as this should work, assuming the fan can tolerate a square-wave voltage :
(Note that stepping up the voltage from 12V to 120V @ 0.2A is problematic without a transformer).

 

[D.A.(Tony)Stewart]

Be aware that the fan start current will be > 500% until back EMF reduces the current.

 

[crutschow]

Addendum to Post #5: To protect against voltage spikes from the transformer leakage inductance, add a diode (e.g. 1N400x series) from each MOSFET drain (anode) to the +12V (cathode).

--- Updated Mar 1, 2025 ---

Be aware that the fan start current will be > 500% until back EMF reduces the current.

The Post #5 circuit should readily handle that.