Satz power packs varying current problem


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I bought 20 of these power packs which are fine for circuits.

Problem is using them for specific heat capacity practical as they don't warm up the heater very well. The current is not stable and the ammeter cycles between 0 and 5, they are also not working well for making electromagnets.

Has anyone successfully managed to stabilise the current so these power packs can be used for all the GCSE pracs? By adding on a resistor / capacitor or something else?

Because at the moment it is looking like an expensive mistake.
 
My specific heat capacity heaters are 55W, meaning at 12V they draw 4.5A.
Your PSUs max out at 1.5A, (18W) so wont work very well.
I dont thing Physics allows a "fix".

For electromagnets you could try putting a 4.7ohm 10W resistor in series with the coil of wire and setting the voltage at 4.5V. This should limit the current to a point where the PSU is reasonably happy.
 

Nick Mitchener

COMMITTEE
all in agreement there, these are only suited to circuits as replacements for cells. Great for lower school until you need to do electromagnets, though you can scale that back and pick up staples.
 

Nick Mitchener

COMMITTEE
I bought a set of those Satz PSUs, so i didn't have to lug the other PH ranger 8.5A PSUs upstairs when they was using ray boxes
I can understand that, I just don't like SATZ, though I would never invest in a set of 1.5A, too limiting, I think a set of lightweight 3A or 4A supplies is very useful. Where I worked we had over 100 PSUs and less than half PH Spacesavers. I think the fact they were mainly reserved for higher school may explain why we had so little trouble with them.
 
We have these PSUs for our KS3 circuit lessons. They're fine for that, but don't work well with things like electromagnets and specific heat capacity. We use different power packs for those experiments, but they're bigger and heavier so not as easy to move around.
 
We have these PSUs for our KS3 circuit lessons. They're fine for that, but don't work well with things like electromagnets and specific heat capacity. We use different power packs for those experiments, but they're bigger and heavier so not as easy to move around.
you don't have the OG satz ones then, they weigh a ton.
 
My specific heat capacity heaters are 55W, meaning at 12V they draw 4.5A.
Your PSUs max out at 1.5A, (18W) so wont work very well.
I dont thing Physics allows a "fix".

For electromagnets you could try putting a 4.7ohm 10W resistor in series with the coil of wire and setting the voltage at 4.5V. This should limit the current to a point where the PSU is reasonably happy.
Thank you, I will try that.
 
The rated output on the PSUs shown is 18W, so they may cope with a 24W bulb.... but for how long??
Have them at 9V, not one failed yet over the years. Cheap and cheerful for that very use over 5kg PH Ranger PSUs going upstairs.

Horses for courses
 
I suspect there's a thermal overload in there that heats when too much current passes and goes open circuit, cools and resets? If it was a semiconductor fuse it would stay high resistance until the load was removed.
 
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