[sdiy] BIG PSU ISSUES

[Dan Snazelle]

wow, those resistors make you lose a whole volt?? damn. i should watch those!

so i did some things to my setup in the last 10 minutes.

1. out of my psu the power was being split into 


A-a run for my CGS vco (to prevent noise by having it all by itself)

B-a run straight into a distro board complete with a 6v regulator, and a few lines worth of power connectors for my modular. Out of this i was taking a 4 foot wire on an mta connector (with +/- 12 v and gnd) and sending that into a breaboard on my bench from which i was splitting the power three ways (star)


Well what i didnt know was that 22ohm resistors cause a 1v drop!! i had them on the distro board AND on my bench. so thats 2 volts right there. and for some reason, going into the distro board (maybe the regulator) first was chopping off even more voltage.


so now, without any resistors (can i use lower than 22ohm for fuses? 2 ohm maybe? less of a voltage drop with those?) I am back to 12 volts, testing load side!!!!


hooray


thanks for all the help



--------------------------------------------
check out various dan music at:

http://www.myspace.com/lossnyc


http://www.soundclick.com/lossnyc.htm


http://www.indie911.com/dan-snazelle
(or for techno) http://www.myspace.com/snazelle


> Date: Wed, 13 Aug 2008 16:02:10 -0700
> From: dlmanley at sonic.net
> CC: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] BIG PSU ISSUES
>
> That should be fine. You need to measure the current and see what your
> load is drawing, you could have a significant drop across those 22 ohm
> resistors (22 ohms * 50 mA = 1.1V). Also if the supply is new to you,
> put a resistive load on it and see if it works properly - ie can it
> deliver the rated current at the rated voltage.
>
> -Dave
>
> Dan Snazelle wrote:
>> i am using 22 gauge solid core wires.
>>
>>
>> is that too big/small??
>>
>>
>> thanks
>>
>> -------------------------------------------- check out various dan music
>> at: http://www.myspace.com/lossnyc
>> http://www.soundclick.com/lossnyc.htm
>> http://www.indie911.com/dan-snazelle
>> (or for techno) http://www.myspace.com/snazelle
>>
>>> Date: Wed, 13 Aug 2008 15:24:59 -0700
>>> From: dlmanley at sonic.net
>>> CC: synth-diy at dropmix.xs4all.nl
>>> Subject: Re: [sdiy] BIG PSU ISSUES
>>>
>>> Dan Snazelle wrote:
>>>> I have a nice powerone supply. its a 12volt or 15 volt +/- volt. I
>> am running it at 12 volts and without a load i used the trimmers to set
>> it for 12volts.
>>>>
>>>> i think this model can handle at least .5 amps per channel. i think
>> actually .75 (in +15/-15 mode it handles less amperage)
>>>>
>>>> now when i hook up my current project, which is three giant
>> breadboards (of mainly CMOS low draw chips) to my STAR breadboard (which
>> is the PSU hooked up to a breadboard which everything else plugs into
>> with 22r resistors as fuses), and i take a reading of the VOLTS of my
>> project i get a reading of 9 volts.
>>>>
>>>> My questions
>>>>
>>>> 1. there are trimmers on the PSU to push it back up to almost 12
>> volts post load..should i do this? or are the trimmers only for PRE LOAD?
>>>> 2. how can i get around this? could my PSU be messed up?
>>>>
>>>> 3. i know these are low amp chips. i only have ONE led on the
>> entire project. there are some opamps.
>>>> is load voltage not the same? do i not need to worry? or should i
>> get a measured 12 volts? and -12 volts?
>>>>
>>>>
>>>> thanks so much
>>>>
>>>
>>> What is the current with the load attached (or if you can't measure
>>> current, as someone else asked, what's the voltage drop across the 22
>>> ohm resistors).
>>>
>>> If you put a resistive load (of proper wattage!) on the supply does the
>>> supply work to spec? The supply could be defective.
>>>
>>> Perhaps a silly reply in this case, but what gauge wires are you using
>>> to hook the supply to the load? I saw someone once blame a supply for
>>> low voltage at the load, and then I asked him why his power wires were
>>> warm to the touch! I guess if the insulation was dripping off, or the
>>> wires started smoking he would have eventually figured it out. See if
>>> there is a voltage drop across the power wires.
>>>
>>> -Dave
>>>
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>
>
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