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I need help how to build a power supply that will input 110 v ac to 24 v dc oupt 2.5 amp. please help me how to schematics, diagram, and part list that i need to get... help help!! thank you
Well a 30V transformer is a bit to much of a high voltage as it'll give 40V so the regulator will have to drop 16V and at 2.5A it will have to burn 40W.
I would use a 24V transformer, an LM338 and a 4700:mu:F 35V filter capacitor.
The transformer and rectifier should also be rated for 4A.
Might be the teacher point is the power dissipation. 2.5 A @ 24 V regulator with zener and transistors is about how to dissipate the power.
3 Amp rectifier has much higher peak current, also most regulator IC providing current limiting and thermal protection. But higher ratings still better.
Assuming the capacitor is large enough to filter out all of the ripple the input current is 1.414 times the output current which is 3.535 and is why I recommend a 4A rectifier.
Most rectifiers can cope with huge surge currents, I've seen ratings as high as 50A for small 1.5A units!
The load discharges the capacitor between the pulses from the rectifiers.
With a large capacitor value or a low load current then the valley voltage doesn't drop as low.
The ripple voltage is a sawtooth shape. The rectifiers charge it to the peak voltage quickly and the load discharges it slower.
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