[sdiy] buchla 200e power supply

Derek Holzer derek at umatic.nl
Wed Nov 19 12:19:04 CET 2008

Thanks Mark and Seb for the details here. Yes, it is probably easier to 
use rectified and regulated AC, I was just curious how this was done 


mark verbos wrote:
> 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.
> Mark
> 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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derek holzer ::: http://www.umatic.nl ::: http://blog.myspace.com/macumbista
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