Author Topic: Do inexpensive CC/CV AC power supplies exist?  (Read 381 times)

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Offline calzapTopic starter

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Do inexpensive CC/CV AC power supplies exist?
« on: June 18, 2024, 05:48:53 pm »
Does anyone make a relatively inexpensive (US$500 or less) low voltage, CC/CV AC power supply (aka AC power source)?  Ideally 0-36 V, 0-3 A, isolated output, V and A fine/coarse knobs and digital displays.  Similar specs to those of countless inexpensive DC power supplies. Variable frequency, programmability, remote control, and polyphase are not needed.  I have a variac, but it doesn’t meet the specs.  And yes, variacs with digital V and A displays are available … but how about a CC control?  When I need low voltage AC for testing, I use a fixed voltage, isolated-output transformer powered by a variac for voltage control.  When current limiting is needed, I calculate the appropriate size resistor and use that in series.  This is really a fixed power mode because the appropriate size resistor will depend on applied voltage.  Pretty clunky compared to when I need similar DC voltage and current for testing … set V and A on HP, GW or BK supply, connect, and go.

AC supplies I’ve found that meet my specs cost upwards of US$1000 and have additional, unneeded features.

Mike
 

Offline exe

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Re: Do inexpensive CC/CV AC power supplies exist?
« Reply #1 on: June 18, 2024, 07:04:41 pm »
I didn't find anything when I looked.

I concluded that my best bet is to use a power opamp (like TDA2003A or something), and some sort of current bipolar limiting circuitry ([1]).
If it's a resistive-like load, then a unipolar conventional power supply with current limiting and a DC-blocking capacitor may work.

But, from my mini-research, people just put a fuse for protection and that's it).

[1] For bipolar current limiting something can be used, see simplified schematic for Keithley 236 SMU: https://www.eevblog.com/forum/projects/how-to-design-fast-bench-supply-with-cc-and-cv/msg3173706/#msg3173706 . But probably something simpler can be designed.
 
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