Author Topic: Variable switching power supply  (Read 25383 times)

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Offline harrimansat

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Variable switching power supply
« on: May 02, 2015, 09:10:16 pm »
0-30V, 0-5A, multiturn pots:






« Last Edit: May 02, 2015, 09:31:02 pm by harrimansat »
 

Online tautech

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Re: Cheap variable switching power supply
« Reply #1 on: May 02, 2015, 09:20:23 pm »
0-30V, 0-5A, multiturn pots:
Shhhh

I'd had hoped these were my little secret.  >:D

Great little PSU's, beaten them up heaps, 100% reliable.

Smart fan cooled
Ripple ~30 mV
5 turn pots. CV or CC
« Last Edit: May 02, 2015, 09:22:20 pm by tautech »
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Offline harrimansat

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Re: Cheap variable switching power supply
« Reply #2 on: May 02, 2015, 09:31:44 pm »
0-30V, 0-5A, multiturn pots:
Shhhh

I'd had hoped these were my little secret.  >:D

Great little PSU's, beaten them up heaps, 100% reliable.

Smart fan cooled
Ripple ~30 mV
5 turn pots. CV or CC

Cheap deleted  :P
 

Online tautech

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Re: Cheap variable switching power supply
« Reply #3 on: May 02, 2015, 09:49:08 pm »
0-30V, 0-5A, multiturn pots:
Shhhh

I'd had hoped these were my little secret.  >:D

Great little PSU's, beaten them up heaps, 100% reliable.

Smart fan cooled
Ripple ~30 mV
5 turn pots. CV or CC

Cheap deleted  :P
Call them cheap if you wish or "well priced".
The only shortcoming IMO is lack of binding posts instead of 4mm banana sockets.
They available on Aliexpress, but of course better pricing in bulk from the manufacturer.  ;)

Several very similar units around, not sure but they might be rebrands.
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Offline rdl

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Re: Variable switching power supply
« Reply #4 on: May 02, 2015, 11:02:34 pm »
There are a few that look a lot like that one on ebay. Some versions have the regular style binding posts. Price runs around $80 US.

http://www.ebay.com/sch/i.html?&_nkw=power+supply+variable+switching&_sacat=0

Why do they insist on putting ground in the middle? And use yellow instead of green?  :palm:
 

Offline atferrari

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Re: Variable switching power supply
« Reply #5 on: May 03, 2015, 01:16:47 am »
Why do they insist on putting ground in the middle?

Why not?

In a scale, ground IS in the middle.
Agustín Tomás
In theory, there is no difference between theory and practice. In practice, however, there is.
 

Offline rdl

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Re: Variable switching power supply
« Reply #6 on: May 03, 2015, 03:23:01 am »
Because ground is rarely used but positive and negative are often used together.



Picture shows jacks, but plugs are also very common.








« Last Edit: May 03, 2015, 03:26:55 am by rdl »
 

Offline T3sl4co1l

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Re: Variable switching power supply
« Reply #7 on: May 03, 2015, 03:42:35 am »
Don't have a clue why they need (think they need?) all those lytics, but design looks pretty solid and safe.  Look at those slots!

Tim
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Electronic design, from concept to prototype.
Bringing a project to life?  Send me a message!
 

Offline dom0

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Re: Variable switching power supply
« Reply #8 on: May 03, 2015, 07:27:17 am »
Why do they insist on putting ground in the middle? And use yellow instead of green?  :palm:

It's not yellow. The socket is green/yellow, the inner sleeve is green ;)

And why in the middle... no idea. The old ones got it right. +,-,PE.
,
 

Offline dadler

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Re: Variable switching power supply
« Reply #9 on: May 03, 2015, 08:55:55 am »
Hmm, these all seem to be 220V. Can't seem to find one with the same essential internals that will work in the USA.
 

Online tautech

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Re: Variable switching power supply
« Reply #10 on: May 03, 2015, 10:14:18 am »
Hmm, these all seem to be 220V. Can't seem to find one with the same essential internals that will work in the USA.
Pulled one from stock to check, yes the manual and the rear of the PSU says......230V.

However the label next to the IEC mains socket has a 110 V option that is blank.
That is, only the 230 V is marked on my units.

This indicates there might be a 110 V version available.
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Online Rerouter

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Re: Variable switching power supply
« Reply #11 on: May 03, 2015, 10:29:26 am »
for a free forum, eevblog sure is expensive to my bank account....
 
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Offline nowlan

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Re: Variable switching power supply
« Reply #12 on: May 03, 2015, 10:49:45 am »
Might want to put the model in the title.
Needs better lighting, suggest outdoors.
Also what is the output like during switch on? Any screen shot?
 

Offline rdl

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Re: Variable switching power supply
« Reply #13 on: May 03, 2015, 11:13:40 am »
...
It's not yellow. The socket is green/yellow, the inner sleeve is green ;)
...

Yes, the socket in the photo in the op is green/yellow - and it actually looks pretty nice. Looking at the results from the ebay search I posted the ones made with regular binding posts all seem to use solid yellow. For some reason the Asian manufacturers just don't seem to care about the details. I have even seen pink binding posts on some power supplies, but hey, they're cheap.
 

Online tautech

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Re: Variable switching power supply
« Reply #14 on: May 03, 2015, 07:48:34 pm »
Might want to put the model in the title.
Needs better lighting, suggest outdoors.
Also what is the output like during switch on? Any screen shot?
Sorry haven't got a saved waveform to post.
I'll try and get one up later today.

NO overshoot.
« Last Edit: May 03, 2015, 08:01:18 pm by tautech »
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Offline rob77

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Re: Variable switching power supply
« Reply #15 on: May 03, 2015, 08:36:00 pm »
the board layout and how it's built.... looks like my Manson bench supply inside.
and actually manson has a very similar model...  http://www.manson.com.hk/products/detail/28
 

Online tautech

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Re: Variable switching power supply
« Reply #16 on: May 04, 2015, 07:24:38 am »
Might want to put the model in the title.
Needs better lighting, suggest outdoors.
Also what is the output like during switch on? Any screen shot?
Sorry haven't got a saved waveform to post.
I'll try and get one up later today.

NO overshoot.
K305D power on waveform

NO LOAD
PSU setting 10 V
DSO settings:
10:1 probe, 2v/div, Trigger @ 2V, Single trigger

Timebase set at 20ms/div to more clearly show a small glitch in the start of the voltage ramp up @ ~3.5V.

Note
Further test with a 12 V bulb at the same 10 V setting displayed no discernable difference in the power up waveform. PSU displayed a 420 mA load.
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Online nctnico

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Re: Variable switching power supply
« Reply #17 on: May 04, 2015, 07:49:52 am »
This seems like a nice little extra PSU for the bench. Would it be difficult to add an output enable switch?
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online Rerouter

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Re: Variable switching power supply
« Reply #18 on: May 04, 2015, 07:58:44 am »
tautech, could you re-try that at something like 3.3V, the little bump at the start has me curious,
 

Offline dadler

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Re: Variable switching power supply
« Reply #19 on: May 04, 2015, 08:14:37 am »
I found this one which is 110v/220v, but I am not sure if the internals/pots are (mostly) the same:

http://www.ebay.com/itm/281663049598
 

Online tautech

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Re: Variable switching power supply
« Reply #20 on: May 04, 2015, 08:24:54 am »
This seems like a nice little extra PSU for the bench. Would it be difficult to add an output enable switch?
Why would you bother if it doesn't overshoot?
The only space available on the front panel is in close proximity to the mains switch.
 Mains and LV  :popcorn:

tautech, could you re-try that at something like 3.3V, the little bump at the start has me curious,
K305D 3.3 V 250 mA Resistive (bulb) load power up



Voltage when Glitch occurs is reduced with a reduction in output setting. Now ~ 2 V.

DSO settings:
10:1 probe, 500 mV/div, Trigger 500 mV, Single shot
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Online Rerouter

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Re: Variable switching power supply
« Reply #21 on: May 04, 2015, 08:30:36 am »
Thank you very much, i just went ahead and ordered one last night anyway, glad to see everything is in order :)
 

Online tautech

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Re: Variable switching power supply
« Reply #22 on: May 04, 2015, 08:46:45 am »
Thank you very much, i just went ahead and ordered one last night anyway, glad to see everything is in order :)
:-+
First one I got, we tried to bust and couldn't.  >:D

2 x 10A stud diodes in series, forward biased for ~1.4 V across the outputs.....no problem, it just cycled the fan when needed.
Want to charge batteries, LA, 24 V (28.4 V @ 5A) ALL weekend....no problem.
They self Current limit @ just over 5A.

Yet to find an application where the fan runs continuously.  8)

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Offline opty

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Re: Variable switching power supply
« Reply #23 on: May 04, 2015, 08:58:47 am »
tautech, could you re-try that at something like 3.3V, the little bump at the start has me curious,

could you please show shut down traces as well?
 

Online tautech

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Re: Variable switching power supply
« Reply #24 on: May 04, 2015, 09:08:52 am »
tautech, could you re-try that at something like 3.3V, the little bump at the start has me curious,

could you please show shut down traces as well?
They will depend on the load. Internal capacitance with no load can take as long as 5 seconds to discharge.
3.3 V:
It is a CLEAN curved ramp downwards, steep at first, just a reverse of the 3.3 V rising waveform without any glitch.
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