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Placid HD BP power supply for higher voltage use
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shadowfax  
#1 Posted : Saturday, February 24, 2018 2:35:09 PM(UTC)
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Hi:

Was wondering if this PS could be configured for an output voltage of +24/-24v for a line section I an working on by
increasing R12... etc. Current usage is less than 1v... I built one for my Buffalo 3 SE dac so I have experience with its
usage.Thanks.
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darienf  
#2 Posted : Saturday, February 24, 2018 3:53:33 PM(UTC)
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Hi, I have a couple of placid hd 1.0 with the ripple mod that I am using for +24×2. All I did was replace c1 with 50v equivalent, supply 30v ac and increase heatsink size. I am drawing about 200ma each. Not sure if the same would apply to the 2.x versions

I would be interested to hear if there is more I could be doing to optmize for 24v. I am generating a lot of heat with 100ma shunt current. For exmple would it be better to be feeding it a lower voltage closer to 24vac? Other changes like r12 (assuming changes are applicabe to 1.0 version) shadowfax is proposing?
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shadowfax  
#3 Posted : Saturday, February 24, 2018 4:23:50 PM(UTC)
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Try 20vac.... From what is used as a transformer to get 24v in my intended application
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darienf  
#4 Posted : Sunday, February 25, 2018 2:29:51 PM(UTC)
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Is it good idea to go with a lower ac input voltage than the intened dc output voltage? I have not been able to wrap my head around how the shunt power supply works but for other types you a higher v input than desired output recommended.
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Brian Donegan  
#5 Posted : Sunday, February 25, 2018 3:35:06 PM(UTC)
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After rectification, the DC voltage will be approximately 1.4x the AC voltage. That's is the DC voltage feeding the regulator.
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darienf  
#6 Posted : Sunday, February 25, 2018 4:21:39 PM(UTC)
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Ah ok, 18 - 20 vac should be plenty then. I guess we use 9vac for our 5v supplies because that is what is availabe.

Any other conderations for 24v?
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Brian Donegan  
#7 Posted : Sunday, February 25, 2018 4:34:01 PM(UTC)
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just make sure all caps are rated for the max DC voltage + 10% or so.

Example: 20VAC transformer = ~28VDC, +10% = ~30.8V, so use a minimum of 35V caps. 50V would be a nice safe value, and allow for variation/error.
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thanks 1 user thanked Brian Donegan for this useful post.
darienf on 2/25/2018(UTC)
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