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Do I need an AC power supply or is a Variac suitable?
F4:
I recently came across a need to inject 15v AC into a circuit that had its own rectifier et all on the board.
Is a dedicated AC power supply and a variac the same exact thing? Looking around at dedicated AC power supplies, they are few and far between compared to DC power supplies so it made me start to wonder.
The main difference I see is that an AC power supply is not limited by the AC voltage from the wall, but what are the other reasons to have a dedicated AC power supply over using a variac?
tggzzz:
What power do you need?
A variac is merely an auto-transformer where the wiper picks off a variable number of turns. It is not isolated from the mains input.
F4:
Thank you.
I have an isolation transformer to put in front of the variac if needed.
In terms of power, 1000 watts would cover 95% of needs.
glitchcatcher:
A variac does not have variable frequency, setting the voltage accurately and stably might be challenging and advanced features like programming, arbitrary waveforms and much more are missing.
But if you just need to supply some AC voltage with mains frequency here and there, it should suffice.
You can look into AC power supplies like Chroma 61504/61604 but yeah, they are hugely expensive.
schmitt trigger:
For power line AC work, a Variac plus an isolation transformer are your lowest cost option.
Lowest cost doesn’t means cheap, the sheer amount of iron and copper makes this things expensive, but not as expensive as a true AC source.
Additionally, it will be far more rugged. A simple fuse can protect against shorts or overloads.
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