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pinnocchio  
#1 Posted : Monday, January 17, 2011 1:03:42 PM(UTC)
pinnocchio

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Hi,

I just finished building and adjusting one of my Placid BP and set for 250mA with +/- 15V

My toroid is a 15V 25VA

The placid heatsinks near the DC out panel are getting close to 70 Celcius (158 F) without any load attached to the placid. Is this normal? Should I have bought 12V 25VA instead?

Thanks
Do
Russ White  
#2 Posted : Monday, January 17, 2011 1:21:19 PM(UTC)
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That is normal, because you shunt is shunting all the current that would normally be used by your load.
pinnocchio  
#3 Posted : Monday, January 17, 2011 1:28:25 PM(UTC)
pinnocchio

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I have connected my IVY III to the Placid BP and measured the voltage to make sure it was not sagging and I noticed that the +15V rail stays perfectly the same but my -15V rail drops to -4.8V.

I have 253mV on the +Rail and -252mV on the -Rail

Thanks
Do
Russ White  
#4 Posted : Monday, January 17, 2011 1:37:06 PM(UTC)
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Adjust the negative rail until it does not sag. If this is version 2.1.2 you can also check R13 and R14 while loaded to see what you are actually shunting with the load connected.
pinnocchio  
#5 Posted : Monday, January 17, 2011 1:57:41 PM(UTC)
pinnocchio

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I have adjusted while fully loaded. It is now stable at -15V.

Is 250mA per rail enough to power the whole IVY III?

Could having +15V and -4.80V caused damage to the IVY?

I have not tested it yet that's why I'm asking.

Last question... If I take a 15V toroid to power the Buffalo II, will it work with the Placid or is it asking too much to go from +/- 23v DC to 5.5v DC ?

Thanks
Do
Russ White  
#6 Posted : Monday, January 17, 2011 2:52:13 PM(UTC)
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That 15V trafo would create big drop, it would run really hot. I would not recommend that.

If the Placid-BP is holding at 15V you should be fine. Just measure the IVY outputs prior to actually using it.
pinnocchio  
#7 Posted : Monday, January 17, 2011 3:12:55 PM(UTC)
pinnocchio

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Hi Russ,

Everything seems to have drop at a stable 14.77 volts on both rails. The only issue is heat. It is still at 65c (150F)

Should I change to higher heatsinks or will it survive a long time at this temperature?

Thanks
Do
Brian Donegan  
#8 Posted : Monday, January 17, 2011 3:15:19 PM(UTC)
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That temp is not bad. Is it attached to a load with those temps?
pinnocchio  
#9 Posted : Monday, January 17, 2011 3:30:05 PM(UTC)
pinnocchio

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Hi Brian,

It is attached to the IVY III

Thanks
Do
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