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Power Supply1.2~30VDC, 1.5A


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The 25VAC transformer produces a peak voltage of 35.4V which is reduced to 33.4V by the rectifier bridge. Then try to turn the voltage down to 1.2V at 1.5A then the regulator will heat with (33.4V - 1.2V) x 1.5A= 48.3W which is way too much heat for it. Luckily it has thermal protection built-in so it shuts down when it gets too hot. If the output is set to 5V and loaded with only 1A then the LM317 will heat with (33.4V - 5V) x 1A= 28.4W which will also cause it to shut down even if it has a HUGE heatsink.

Therefore reduce the voltage from the transformer.  

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I guess one of the learning experiences when one gets into this hobby should be blowing things up so that you learn how not to. I just posted these from the archive that the user posted because just about everything was a pdf file save the schematic. I have no idea what format the design files were in or what program they open with so ymmv. I get why you'd want to use a linear regulator for a quick and dirty supply but I don't understand their ubiquitous use with newbies. You don't really learn anything designing with them in my opinion. Trying to design one with discrete components on the other hand...

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