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Main => Main Forum => Topic started by: postalp123 on December 12, 2006, 10:55:57 am

Title: Is 7-volts too much for a 5-volt requirement?
Post by: postalp123 on December 12, 2006, 10:55:57 am
As posted before, I was looking for a power source for my druin board (requires 5-volts).

I managed to find an old AC adapter running 7-volts AC, is this too much for the Druin to handle?

Thanks!
-PP
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: ChadTower on December 12, 2006, 10:58:15 am

Depends on the application, really.  No way to answer that without knowing what it's being fed into.  Lots of 5v things get 7-8v in and regulate it down inside.  Lots don't.
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: postalp123 on December 12, 2006, 11:02:29 am
Quote from: ChadTower on December 12, 2006, 10:58:15 am

Depends on the application, really.  No way to answer that without knowing what it's being fed into.  Lots of 5v things get 7-8v in and regulate it down inside.  Lots don't.

For the record heres what I'm powering:
http://ca.geocities.com/druins22@rogers.com/ls30/

(http://ca.geocities.com/druins22@rogers.com/ls30/RIRev5.jpg)
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: Ed_McCarron on December 12, 2006, 11:04:47 am
Not really familiar with that board, but looking at it I'll make two assumptions:

That theres no regulator, unless theres one built into the chip.  Not likely.

It wants DC, not AC.  That reg won't work regardless of voltage.  Looks like DC in is on the top barrier terminal, and ties right to +5v and gnd.  The electrolytic cap is for filtering.  No regulation/rectification.
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: Ed_McCarron on December 12, 2006, 11:06:46 am
Looked at the schematic.

5v DC only.

Can you pull it from a drive connector on the computer you have in there?  I assume this is a MAME app?
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: ChadTower on December 12, 2006, 11:11:54 am

If I recognize that chip properly, it's just an eeprom.  No voltage changing whatsoever.
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: Havok on December 12, 2006, 12:05:09 pm
Why can't you pull 5v from the computer power supply? I would think that is the best solution. Both the Ipac and Keywiz\GPWiz have a 5v tap for just this thing. Worse case - buy a universal adapter for $10 and wire that up...
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: Ed_McCarron on December 12, 2006, 12:46:36 pm
Quote from: ChadTower on December 12, 2006, 11:11:54 am

If I recognize that chip properly, it's just an eeprom.  No voltage changing whatsoever.

ATMEL is all about microcontrollers now... Judging by the fact that its the only chip there, thats what I'd assume it is.
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: rockin_rick on December 16, 2006, 07:12:11 pm
Quote from: Ed_McCarron on December 12, 2006, 12:46:36 pm
Quote from: ChadTower on December 12, 2006, 11:11:54 am

If I recognize that chip properly, it's just an eeprom.  No voltage changing whatsoever.

ATMEL is all about microcontrollers now... Judging by the fact that its the only chip there, thats what I'd assume it is.

Yes, it is a microcontroller.  Feeding it 7V will not work.

Rick
Title: Re: Is 7-volts too much for a 5-volt requirement?
Post by: Kevin Mullins on December 16, 2006, 09:23:58 pm
Maximum DC voltage listed is 6.0v ......... DC
http://www.atmel.com/dyn/resources/prod_documents/doc1477.pdf (http://www.atmel.com/dyn/resources/prod_documents/doc1477.pdf)

As already mentioned....
Use the 5.0v DC from a PC power supply if this is indeed for a MAME project or something similar that is using a PC.