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 Forum index » DIY Hardware and Software
power supply ebay?
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flab



Joined: Feb 13, 2012
Posts: 60
Location: Glasgow

PostPosted: Sat May 11, 2013 4:04 pm    Post subject: power supply ebay? Reply with quote  Mark this post and the followings unread

hi there ,
here is a power supply i found at ebay - there are a few more or less same kits most of them located in china -

http://www.ebay.co.uk/itm/150796179431?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

the above kit's components are in common with the most digital schematics - so i say it ll work fine -

-is it a wise choice for modules ?
any other kit to suggest maybe ?

cheers
petros
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piedwagtail



Joined: Apr 15, 2006
Posts: 157
Location: shoreditch
Audio files: 1

PostPosted: Sat May 11, 2013 6:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

http://www.ebay.co.uk/itm/300700312773

you could use two of these if you want
then you don't need a transformer.
One unit V+ and the other unit V- pair with your ground terminals.
L and N are paralleled. The remaining v+ and v- are your +/-15.

(caveat: switching frequency differences between units)
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flab



Joined: Feb 13, 2012
Posts: 60
Location: Glasgow

PostPosted: Sun May 12, 2013 3:44 am    Post subject: Reply with quote  Mark this post and the followings unread

piedwagtail ,

cheers for the suggestion

have you ever used them ?

the fact that ll be
switching voltage differences
between units sounds a bit scary -

but again there is no transformer needed that is positive
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piedwagtail



Joined: Apr 15, 2006
Posts: 157
Location: shoreditch
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PostPosted: Sun May 12, 2013 4:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Well they'll be putting out their 15V.
In theory if one is switching at 50kHz and the other at 50.2kHz for instance they could produce a beat frequency ripple; in practice the filtering should swamp this form of ripple.
These concerns come from the audio community who fret over ps noise reaching their microphone level signals.In synth modules the signals fed around are huge in comparison.
I've so far used these for my valve heater circuits and it's remarkable to have no filament hum levels present.The packages are so small and efficient.

I'm in the process rebuilding my modular and I will go this route; it not only cuts out the transformer(including any mechanical noise) but also the rectifier,regulation,caps,circuit boards too. I had four separate linear psus in the box; quite a weight.
These could also be used for distribution and then using step down/linear regulation at critical boards such as vcos.
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flab



Joined: Feb 13, 2012
Posts: 60
Location: Glasgow

PostPosted: Sun May 12, 2013 9:41 am    Post subject: Reply with quote  Mark this post and the followings unread

cheers for making it clear
well when comes to power supplies and electricity
i cant really say

you say "These could also be used for distribution and then using step down/linear regulation at critical boards such as vcos." it needs to have an output of 18v so when that will pass from the regulator will have 15v output - because my vcos run at 15

is there a way to calculate roughly, how many modules can this support ?
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piedwagtail



Joined: Apr 15, 2006
Posts: 157
Location: shoreditch
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PostPosted: Sun May 12, 2013 9:42 am    Post subject: Reply with quote  Mark this post and the followings unread

Ok, since I've opened my mouth,I'll jump off the fence...

Just ordered two of the above
and two
http://www.ebay.co.uk/itm/290684767437
to evaluate
The 24V will be for vcos and to investigate high end regulation strategies.


DC VOLTAGE: 24V
RATED CURRENT: 1A
CURRENT RANGE: 0~1A
RATED POWER: 24W
RIPPLE & NOISE (max.): 200mVp-p
OUTPUT VOLTAGE ADJ. RANGE: 21.6~26.4V
VOLTAGE TOLERANCE : ±1.0% 
SETUP, RISE TIME: 300ms, 30ms/230VAC
VOLTAGE RANGE: 100~264VAC
EFFICIENCY (Typ.): 77%
OVERLOAD: 180~220% rated output power
SAFETY STANDARDS: EN60950-1 approved
DIMENSION OTHERS: 96*58*25mm (L*W*H)
WEIGHT 0.120Kg

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Also offered for these
http://www.ebay.co.uk/itm/Ultra-Mini-size-Red-LED-Volt-Meter-4-5V-30V-Doesnt-Require-Power-/160774132964
So the rails can be observed and shorts/overcurrents can be quickly detected.
Posted Image, might have been reduced in size. Click Image to view fullscreen.

....The current consumption of this voltage meter amazing only is 5mA, it doesn't require extra power supply, So it can work continuously for 24 hours...
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piedwagtail



Joined: Apr 15, 2006
Posts: 157
Location: shoreditch
Audio files: 1

PostPosted: Sun May 12, 2013 9:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Yep, hence 24V for dropout clearances.

There's few modules sinking more than 50mA a rail; sequencers etc excepted.
2A is a lot in this case....but useless at 6.3V for valve filaments!
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