General > General Technical Chat
Show your favorite and most used benchtop PSU
Whales:
--- Quote from: switcher on April 24, 2014, 12:29:33 pm ---WOW! I wouldn't want to fall asleep at the bench using that PSU!
--- End quote ---
The OCP kicks in rather early and keeps the unit down until a power cycle. None the less, I don't let anything run while I'm asleep -- I've had mere AA batteries melt their holders out overnight before, something I don't want to repeat with anything else.
--- Quote from: c4757p on April 24, 2014, 12:41:52 pm ---At least round off the tops...
--- End quote ---
I've spent a lot of time making sure there was no way for my alligator clips to short out on one another, but I have not thought much about the mechanical safety of the nails. I'll smooth them off :)
--- Quote from: AlfBaz on April 24, 2014, 01:01:59 pm ---No, No, no!
Sharpen them up more!
Serves to purposes
1. no need to strip wires, just pierce the insulation
2. It'll teach you about touching live components :)
--- End quote ---
xD
Shaw is a power supply. It menaces with spikes of brass.
FYI the negative rails are merely token: draining more than a few mA across them and any other rail kills the unit. Even at the full potential of 24v, it's not enough to cause you harm when applied externally.
My biggest concern when making this puppy was the choice of computer power supply. Not all PSUs are safe designs in the first place, let alone after years of moisture, heat and dust abuse. Investigation what they are made out of is important.
Eg, would you call this a well designed 12V regulator?
From Death of a Gutless Wonder I. It's a great read, as are the two sequels.
Some designs do the same to create a 3.3V rail from the 5V rail. 2*0.7 approx vdrop on the diodes -> approx 3.6V. Not exactly best or safe practice, but it happens.
Making sure your unit has useful OCP is also important. If it self destructs before the OCP/UVP kicks in, then it might as well not be there. Similarly some units are designed to fail the silicon before anything else in order to protect the expensive glass fuses. You can't have customers ringing up and complaining about how much fuse replacement costs -- it would defeat the whole purpose of not having a public phone number or traceable manufacture!
(Yes these units are probably illegal in most countries, but nobody notices/cares. Don't trust cheap/free power supplies.)
mtdoc:
--- Quote from: Whales on April 24, 2014, 11:48:05 am ---
Pins are nails soldered onto small FR4 squares.
--- End quote ---
Hmm... A new type of "bed of nails" testing perhaps :-//
peter.mitchell:
--- Quote from: Whales on April 25, 2014, 12:36:50 am ---long post that i want to quote but only to show i refer to you
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This all applies to car PSUs for computers too;
THIS IS NOT AN ACCEPTABLE ATX PSU NOT EVEN FOR A CARPUTER!
Spend 3x the amount, get something like this, which is still sweet fuck all and get something that won't cook a few transistors every time you start your car!
Whales:
--- Quote from: peter.mitchell on April 25, 2014, 10:44:20 am ---THIS IS NOT AN ACCEPTABLE ATX PSU NOT EVEN FOR A CARPUTER!
--- End quote ---
Link is not working for me.
peter.mitchell:
fixt
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