Transformer Questions

Caeberos · 02-03-2004, 09:10 PM

A friend of my has an old HP Jordana Organizer and the power transformer (the thing you plug into the wall, that is what it is called right?) is basically dead, it is 12v at 400ma, it also uses a special plug to get power into the Jordana unit. They asked me if i could fix it and I am planning to cut off the plug and solder it to a working 12v transformer, I am pretty sure that the amperage on the new unit does not matter as long as it is higher than 400ma is this is the case? I just don't want to fry the thing since it isn't mine.

UberBlue · 02-03-2004, 10:41 PM

Yep. 12V and greater than 400ma is all you need.

Caeberos · 02-04-2004, 09:39 AM

Thanks (why do messges need to be longer than 10 characters?)

KnightElite · 02-04-2004, 10:40 AM

Probably so people don't spam the boards with nonsense posts. (such as nothing but a smiley)

guandi · 02-04-2004, 11:58 AM

krazy · 02-17-2004, 01:14 AM

You also need to make sure that if the old transformer was DC, the new one is also DC, and vice versa. If you need a DC transformer and all you have is an AC version with the correct volt/amp parameters, it can be converted with a full bridge rectifier and maybe a few capacitors for filtering. This will drop the voltage ever so slightly however (maybe a fraction of a volt).

Brians256 · 02-17-2004, 08:59 AM

Also, you described an unregulated power supply. This means that different loads on something like that will get different voltages. You might want to make sure that you use something like a 7812 chip to regulate it, because mfgs use a specific transformer thats just right for the load, and you might not get lucky. Search for 7812 circuits.

On the other hand, it might work just fine. It depends on the power filtering circuits in the device being powered.

02-03-2004, 09:10 PM	#1
Caeberos Cooling Neophyte Join Date: Mar 2003 Location: New York Posts: 32	Transformer Questions A friend of my has an old HP Jordana Organizer and the power transformer (the thing you plug into the wall, that is what it is called right?) is basically dead, it is 12v at 400ma, it also uses a special plug to get power into the Jordana unit. They asked me if i could fix it and I am planning to cut off the plug and solder it to a working 12v transformer, I am pretty sure that the amperage on the new unit does not matter as long as it is higher than 400ma is this is the case? I just don't want to fry the thing since it isn't mine.

02-04-2004, 10:40 AM	#4
KnightElite Cooling Savant Join Date: Sep 2002 Location: Saskatoon, Saskatchewan Posts: 294	Probably so people don't spam the boards with nonsense posts. (such as nothing but a smiley) __________________ Can anyone else here say that they have a watercooled monster that's 45" tall?

02-04-2004, 11:58 AM	#5
guandi Cooling Savant Join Date: Dec 2003 Location: UK Posts: 174	__________________ A8N-SLI Deluxe FX55@3ghz 2x TwinX1024-3200XL 2x BFG6800Ultra Audigy2 ZS + Gigaworks S750 2x120gb/4x80gb lots of water/copper/pumpy goodness.

02-17-2004, 01:14 AM	#6
krazy Cooling Savant Join Date: Mar 2003 Location: St. Paul, Minnesota, USA Posts: 123	You also need to make sure that if the old transformer was DC, the new one is also DC, and vice versa. If you need a DC transformer and all you have is an AC version with the correct volt/amp parameters, it can be converted with a full bridge rectifier and maybe a few capacitors for filtering. This will drop the voltage ever so slightly however (maybe a fraction of a volt). __________________ Abit NF7-S ... xp1800+ ... Abit GF4ti4200 ... Maxtor 120gb SATA150 Currently gathering parts to water cool everything! (read about the project)

02-03-2004, 10:41 PM	#2
UberBlue Cooling Neophyte Join Date: Jul 2003 Location: WA Posts: 95	Yep. 12V and greater than 400ma is all you need.

02-04-2004, 09:39 AM	#3
Caeberos Cooling Neophyte Join Date: Mar 2003 Location: New York Posts: 32	Thanks (why do messges need to be longer than 10 characters?)

02-17-2004, 08:59 AM	#7
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	Also, you described an unregulated power supply. This means that different loads on something like that will get different voltages. You might want to make sure that you use something like a 7812 chip to regulate it, because mfgs use a specific transformer thats just right for the load, and you might not get lucky. Search for 7812 circuits. On the other hand, it might work just fine. It depends on the power filtering circuits in the device being powered.

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