Electronics > Projects, Designs, and Technical Stuff
Convert 24AC to 12VAC/DC 1.5A
Ian.M:
Yes, the LMZ14202HTZ should work as long as the 24V AC supply's total regulation + tolerance is better than 15%, and if its close to 15% use silicon diodes for the bridge rather than Schottky ones. However its going to be right on the edge with high line & light load.
I doubt you could make a 50 or 60Hz 24V:12V transformer to fit the volume limit that can handle the current, even without the rest of the regulator circuit. Also 12V RMS will need a *MUCH* larger reservoir capacitor to ride through the zero crossings. An autotransformer to buck the AC by only 2V - 3V to get enough safety margin for the DC-DC converter would be smaller, but I'd be surprised if its small enough.
Zero999:
If regulation is unimportant and you're fine with winding your own transformer, then how about a Royer converter? Look up compact fluorescent or electronic transformer circuit and modify it to work of 24VAC, rather than mains. A rectifier and smoothing inductor/capacitor will need to be added to the secondary to convert it to DC. Use Schottky diodes for low voltage loss and fast switching.
http://educypedia.karadimov.info/library/AN00048.pdf
https://www.st.com/resource/en/application_note/cd00003902-electronic-transformer-for-a-12v-halogen-lamp-stmicroelectronics.pdf
Such a circuit can also be used to reduce the voltage to a suitable level for more common buck regulators, as well as providing isolation. See figure 15, page 12 of the TC33167 data sheet for an example.
http://www.ic72.com/pdf_file/t/85248.pdf
mikerj:
--- Quote from: connectTek on March 27, 2020, 10:25:25 am ---Thanks again guys.
Just a thought, can I convert the 24vac to 12vac using a small toroid transformer ( hand made)?Regulation is not to important
--- End quote ---
Depends on how much current you want to draw from it. If the 1.5A applies to the 12VAC supply (i.e. 18VA), then the volume of the transformer will be larger than the space you have.
connectTek:
Found these.
https://www.avebiej.com/dm03-dcdc-855v-to-5v-12v-2a-power-supply-converter-step-down-module-batch-p-338454.htm
With a smd bridge rectifier , should be perfect.
Thanks again guys for all your advice.
Much appreciated for your time.
Cheers
NiHaoMike:
Exactly what is the load that can accept 12V AC or DC?
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