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Old 27th February 2014, 07:07 PM   #21
infinia is offline infinia  United States
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mmmm... where's the beef LOL'
I'll bite... what is the "required" ripple current rating for this meaty experiment.
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Old 27th February 2014, 08:00 PM   #22
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Infinia, you are sounding silly.

For a cap in the reservoir position, (ie after a trafo and bridge), the current peaks from the "top-up" effect cause local cap heating. Simple ohms law (I^2R) with the Internal resistance.

One problem is it is difficult to quantify the heating effect of this current since it is short pulses every mains cycle. The specs are probably RMS related. In an audio application where the current is the load, which then gets reflected back to the cap top-up pulses, this varies enormously.

The temperature rating is ambient. In a big computer PSU delivering constant 100s of amps this can be critical.

In audio?? It should be easy to conservatively rate reservoir caps, but you go ahead and stick big ones in and be happy.
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Old 27th February 2014, 08:03 PM   #23
infinia is offline infinia  United States
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silly? I design offline SMPS usually starting with half wave voltage doublers or full wave directly connected to the mains
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Old 27th February 2014, 09:03 PM   #24
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Quote:
Originally Posted by infinia View Post
silly? I design offline SMPS usually starting with half wave voltage doublers or full wave directly connected to the mains
This is exactly what is found inside of servers and other types of electronic office equipment. It is typically configured on its own PC board away from other circuitry. It is well shielded from the chassis with thick plastic. There are also little lightning bolts on the PC board to warn people not to poke around it.

The output voltage is also isolated from the mains with a high frequency transformer.

I was shocked when I discovered this. But it makes sense for a switching power supply.

Please do not recommend this procedure for DIY. You have no idea how much a reader may or may not know about electricity. I know that we have some pretty green noobs lurking and sometimes posting. Let's not kill them off.
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Old 27th February 2014, 09:24 PM   #25
infinia is offline infinia  United States
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Originally Posted by Fast Eddie D View Post
Please do not recommend this procedure for DIY. You have no idea how much a reader may or may not know about electricity. I know that we have some pretty green noobs lurking and sometimes posting. Let's not kill them off.
no it's not a procedure it's a recognized technique of SMPS described in words. I'm not suggesting to anybody to build a mains connected circuit to check their ripple current specs.
silly indeed


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I was shocked when I discovered this.
you shouldn't be messin around with stuff with warnings. LOL
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Last edited by infinia; 27th February 2014 at 09:48 PM.
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Old 27th February 2014, 10:00 PM   #26
infinia is offline infinia  United States
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My pearls of wisdom go ridiculed by the audiophilla masses.
sad
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Old 28th February 2014, 03:16 AM   #27
godfrey is online now godfrey  South Africa
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I'm sure your first post in this thread was taken seriously. The LOLs, not so much.
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Old 28th February 2014, 03:21 AM   #28
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Originally Posted by infinia View Post
no it's not a procedure it's a recognized technique of SMPS described in words. I'm not suggesting to anybody to build a mains connected circuit to check their ripple current specs.
silly indeed
No, I'm saying that it's a bad idea to recommend transformerless power supplies for DIYers. It's freaking dangerous.

I'm well aware of how modern commercial industrial electronic equipment is designed and manufactured.

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you shouldn't be messin around with stuff with warnings. LOL
Ha ha I thought about that after I posted.

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My pearls of wisdom go ridiculed by the audiophilla masses.
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Not really. I get your point. Do you get mine?
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