Power Supply Suggestions please..

[Jonathan]

So you really think that they will be too much for 5 steppers

There's nothing wrong with having too much power available - it's just generally doesn't make economic sense.

and a few low amp (Less than 5A) power supplies providing 12V 18V 24V and maybe even 36v. I will be using circuits based on LM317's (or equiv) driving 2n3055s...

Earlier you said you didn't want to make a power supply when it was just a transformer, rectifier and capacitor, but now you're suggesting a lot more components to get what you could have made for less money by just using the correct voltage transformers. For the 12V and 24V you could have used a transformer with two 9V secondaries, which would be much cheaper, easier and more compact. 36V can be had from the stepper motor transformer. 18V from a 12V transformer.

A linear PSU made with LM317's and 2n3055 transistors may work, but the power it dissipates will be huge. Say you're using 12V at 5A - the voltage across the transistor Collector-Emitter junction is 32.8-12=20.8V. At 5 amps that means your transistor has to dissipate 20.8*5=104W. The absolute maximum rating for that transistor is 115W (TIP3055 only 90W), but that's not enough since as the transistor junction to case thermal resistance is thermal resistance is 1.5°C/W, even with a perfect heatsink it can only dissipate (150-25)/1.5=83W at 25°C ambient. Add to that another few of these circuits and your control box is going to turn into an oven unless you're planning on linking it to the spindle water cooling!

This concept is workable if the power dissipation is less, which is likely to be the case for the 24V output, but it seems a lot of hassle and expense when you could have just got a transformer, or two, with the right voltages and VA rating to start with. The only reason I'd do it is if the devices you're powering need the high power quality (low ripple in particular) delivered by a linear supply, which seems unlikely.

Jonathan, Check your mail..

I have...