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Quick test of the PS-305D PSU

PostPosted: Thu Jul 18, 2013 5:44 am
by matseng
I ran some basic measurements on the PS-305D (Linear 0-30V/0-5A, 1mA Display) I recently bought from Smart-Prototyping.

The internal volt meter in the PSU seems reasonably well calibrated.
Code: Select all
PSU    DMM
0.0   0.02
0.5   0.54
1.0   1.08
2.0   2.07
5.0   5.07
10.0  10.07
15.0  15.03
20.0  20.03
25.0  25.03
30.0  30.04
31.1  31.16


Then I tested the Constant Current capabilities with having a direct short circuit through my DMM.
It was very hard to adjust currents below 30mA, but that is expected in short circuit mode
Code: Select all
PSU     DMM
0mA     0.5mA
3mA     3.1mA
20mA    20.5mA
100mA   102.5mA (1.2v)
500mA   513.4mA
1.00A   1.00A (3.1v)


I connected a 12V led bulb with the PSU set at 12.0 volt output. Now the current could be adjusted reasonably well even below 30mA
Code: Select all
255mA   263mA   (CV mode)
100mA   102mA   (CC mode 10.4v)
20mA    20.8mA    (CC mode 9.2v)


I then set the PSU to 5 volts and connected it to an oscilloscope to see how it behaved during power-on.

PS305D-PowerOn.png


I'll definitely not have anything sensitive connected to the PSU during power-on! WTF! A -9 volt spike, followed by a +6 volt spike and then a normal ramp up to 5. At power off it behaved much better. Just a little flutter and then a ramp down to zero. This is with the PSU unloaded, it might behave better is there's a small load on it.

I have to make some additional measurements and have look at the schematics to see if I can find a solution to this shite behavior...

Re: Quick test of the PS-305D PSU

PostPosted: Thu Jul 18, 2013 7:10 am
by neslekkim
thanks for the review. Too bad with that spike... how about when you turn it of?, similar?

Re: Quick test of the PS-305D PSU

PostPosted: Thu Jul 18, 2013 7:16 am
by matseng
I'll make some additional oscilloscope readings for both power on and off, and also with a 10mA load applied as well and see what's happening then.

I've also burned out a 10 watt power LED (350 mA @ 27 volts) by setting the PSU at full voltage and the CC at 350 mA and then applied the LED. So it seems like the current limiting takes a while to kick in - long enough to fsk up a LED capable of peak currents up to 2 amps.

I'll try to get some readings of that as well.

Re: Quick test of the PS-305D PSU

PostPosted: Thu Jul 18, 2013 7:20 am
by neslekkim
seems like all these cheapies need to be turned on before you connect stuff, and disconnect stuff before you turn them off.. I found some Atten APS3005 types that looked promising in the pricerange also, but seems like they also are not behaving good..

Re: Quick test of the PS-305D PSU

PostPosted: Thu Jul 18, 2013 8:23 am
by neslekkim
btw, did you find schematics for these?
One here tries to fix one of these psu's:
http://www.youtube.com/watch?v=Osc1--tmzlQ

And some swedish mods:
http://elektronikforumet.com/wiki/index.php/LW_PS-305D

Re: Quick test of the PS-305D PSU

PostPosted: Sun Jul 21, 2013 4:35 am
by jaromir
Matseng, could you, please, do simple transient measurement?
Attach oscilloscope to output, set voltage to 10V or so, set current to say 100mA, prepare approx. 5Ohm load, and attach the load. Current limitation should take over and - ideally - no current spike should be visible. Then, remove load, current limitation should release the output voltage and - ideally again - no voltage overshot should be visible.

Re: Quick test of the PS-305D PSU

PostPosted: Sun Apr 05, 2015 8:33 pm
by Ada4
I just did a quick check on a 305D. Driving a ~6 ohm ww at 2.5 volt / .5 amp, I get a .5volt overshoot and ~.008 volt / 60hz ripple.