[sdiy] buchla 200e power supply

mark verbos mverbos at earthlink.net
Wed Nov 19 07:21:22 CET 2008

Hi guys, sorry I'm late on this one....

The 2 unit case that Buchla is selling has a PCB with a PT6202A and a  
PT5062A on it. These are a 5volt and +/-15 volt respectively DC-DC  
converters. Also on that board is a simple passive circuit. The  
signal from the 12 volt DC wallwart has a small electrolytic to  
ground before it goes, before each converter, to a ceramic cap to  
ground, then through a ferrite bead then another ceramic to ground,  
then into the DC-DC converter. Each of the 3 outputs then goes  
through a ceramic to ground, an electrolytic to ground then through a  
ferrite bead, then a ceramic to ground before the power connector.  
Sadly, I don't know what the values or part numbers of these parts  
are. These are about $20 each.

The big 200e cases use Cincon DC-DC converters. I don't know the  
model of them,but I can tell you that they are the big square ones  
and it's 3 of 'em in there. I'm guessing CHB75 series, since they're  
the biggest 12 volt input ones Mouser has. Those give out 15A at  
5volts and 5A at 15 volts. I would guess they are similarly treated  
as in the other cabinet, but I don't know. These are $83.85 each in  
the latest Mouser catalog.

I have worked on a 259 module that was mounted in the smaller case  
and it worked fine. No hi frequency bleed through, but the switching  
frequency on these things is 300kHz or more, but I suppose there  
could be some subharmonics that leak through. They have Thermal  
shutdown, short circuit protection and over voltage protection built  
in. They're likely much more GREEN and weigh much less than a linear  
supply, plus easier to use in other countries. With a switching 12  
volt wallwart, it could probably work with any voltage from 100-250.


On Nov 15, 2008, at 2:29 PM, Seb Francis wrote:

> Hi Derek,
> Have a look here:
> http://www.linear.com/pc/viewCategory.jsp?navId=H0,C1,C1003,C1042
> Look at Inverting and possibly Step-Up (Boost) regulators.
> But to implement well enough so you will have clean analog power  
> takes more than a few components.  You will see basic typical  
> circuits in the datasheets that show only a few external  
> components, but to get rid of the high frequency switching noise  
> from the DC you need further filtering and/or linear regulation.   
> Also, the choice of certain components such as the inductor can be  
> quite critical to good performance.
> All in all I would say that for SDIY you would be better using a  
> single AC wall wart and half-wave rectifying to get dual DC.  I've  
> used this on quite a few projects where I wanted an external  
> transformer.  Look at the power supply sub-circuit for this:
> http://burnit.co.uk/sdiy/index.php?page=boxotrix&subpage=schematic
> This is using adjustable regulators so is slightly more complicated  
> than if you were to use fixed like 7812/7912.  Also, ignore all the  
> caps on the right, they are just decoupling used throughout the  
> whole device.
> Seb
> Derek Holzer wrote:
>> Hi Magnus,
>> thanks! Do you have any references for using this in a SDIY  
>> context? Or at least some component names so I can look up  
>> datasheets?
>> D.
>> Magnus Danielson wrote:
>>> Derek Holzer wrote:
>>>> I just read that the Buchla 200e system gets powered by a 12V DC  
>>>> wall wart, or by a single 12V battery. How would one get a  
>>>> usable dual power supply using a single DC source? Or does the  
>>>> Buchla PS give +12V and -12V from the wall wart?
>>> They could be using modern DC-DC converters. It's off the shelf  
>>> components or designs and when executed correctly reliable and  
>>> not producing much excessive heat.
>>> Cheers,
>>> Magnus
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