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Old Jul 20, 2012, 09:10 AM
jrb
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Neg Post Isolation Radio Shack 25 amp PSU

Im getting a 2nd Radio Shack 25 amp PSU (22-510: 13.8V DC 25A Switching Power Supply) and plan to use them in series to power my iC3010B.

Has anyone done a Neg Post Isolation conversion?

TIA,

Jim
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Old Jul 20, 2012, 09:36 AM
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Given that this is a dc power supply and not a computer power supply are you sure that the dc neg is connected to ground? I'm not sure if ALL dc power supplies are setup that way. Be easy enough to check with a multimeter.
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Old Jul 20, 2012, 10:08 AM
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I planned that to be the 1st thing I would do; I'll check my MasTech too.
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Old Jul 20, 2012, 03:25 PM
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The MasTech lets you know right up front!

And, the Radio Shack rings out to the case being ground & the negative post being isolated -- floating.

With the RS on I can plug the connect the charger (iC3010B) w/o issue; unlike on my biggest PC PSU -- needs to be connected then powered up.

Is that typical of PC & Server PSUs?
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Old Jul 20, 2012, 04:37 PM
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Is that typical of PC & Server PSUs?
Likely, yes. Most PC and server supplies have sophisticated short circuit, overcurrent, overvoltage, and undervoltage protection that is lacking in many consumer grade supplies.

Plugging a charger into a server supply that is up and running can engage the overcurrent protection circuitry. It's for this reason that it's always wisest to first connect the charger to the power supply and then power up the supply, as previously discussed.

Mark
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Old Jul 20, 2012, 06:17 PM
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Guess that will keep the local club from getting some from Feather.

They were thinking 4 -- two 12s & a 24.
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Old Jul 20, 2012, 07:45 PM
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I have both IBM and Dell server power supplies which can be powered up without any load attached and then the load ,charger(s) connected without any issues.

I would suggest contacting Feather and having him give you the first hand low down on the ones your club is considering.

Charles
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Old Jul 20, 2012, 08:28 PM
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Will do Charles; thanks once again -- con-grats!
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Old Jul 20, 2012, 08:57 PM
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Depends on the particular PS and the input capacitance of the charger in question. I have some HP and IBM supplies that never experience shutdown when connecting a charger and others that nearly always experience a current fault upon connection.

The easy solution here is to simply connect the charger prior to turning on the supply or to use a current-limiting power-up resistor to charge the input capacitors if the PS has to be on all of the time.

Mark
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Old Jul 21, 2012, 07:28 AM
jrb
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Originally Posted by mrforsyth View Post

The easy solution here is to simply connect the charger prior to turning on the supply or to use a current-limiting power-up resistor to charge the input capacitors if the PS has to be on all of the time.

Mark
Thanks Mark!

Can you think of a way we could incorporate a resistor into a club's charging station?

TIA,

Jim
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Old Jul 21, 2012, 10:29 AM
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Some ideas....

http://www.rcgroups.com/forums/showthread.php?t=759403

http://scriptasylum.com/rc_speed/nospark.html

Mark
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Old Jul 26, 2012, 04:18 PM
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Just tested my two Radio Shack 25amp switching supplies in series might be a bit short compared to the 652 I got out of the MasTech: 23.5a, 27.2v, 643w, consumed 752w @ 6.3amps.

Measured 0 vdc & 0 vac between the cases.
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Old Jul 27, 2012, 07:19 PM
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Just enough:
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