a/c adapter


  #1  
Old 08-23-06, 10:02 AM
A
Member
Thread Starter
Join Date: Mar 2006
Posts: 124
Upvotes: 0
Received 0 Upvotes on 0 Posts
a/c adapter

I have to replace an adapter for a guitar effects pedal. The one that came with its was 9V 500ma. None of the local electronics stores in my area carry it. One place I went to tried to sell me on a 11v 800ma adapter. The guy told me it would work fine, that the device would only pull the power it needs. I didn't buy it because I'm not sure he knew what he was talking about. Is he right about this?? thanks
 
  #2  
Old 08-23-06, 10:15 AM
mattison's Avatar
Member
Join Date: Mar 2003
Location: Cinti, OH
Posts: 5,315
Upvotes: 0
Received 0 Upvotes on 0 Posts
I couldn't find any in our store but Radio Shack has one.

You may have to copy and paste the link.
http://www.radioshack.com/product/index.jsp?parentPage=search&summary=summary&techSpecs=techSpecs&currentTab=summary&cp=&custRatings=custRatings&features=features&accessories=accessories&productId=2049687&origkw=9+volt+power&support=support&kw=9+volt+power&tab=techSpecs
 
  #3  
Old 08-23-06, 10:22 AM
G
Member
Join Date: Oct 2002
Location: Hamilton County, Ohio
Posts: 3,927
Upvotes: 0
Received 2 Upvotes on 2 Posts
9V vs 11V= 22% over voltage. Don't think I'd trust it. Check "the shack" for a 9 - 13 volt 800 ma adapter. You can set it for 9 V. Costs about $18.

=
 

Last edited by DIYaddict; 08-25-06 at 09:29 AM. Reason: Deleted only empty space with no words
  #4  
Old 08-23-06, 12:39 PM
J
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 8,044
Received 517 Upvotes on 422 Posts
The voltage must be the same volts and the same AC or DC.
The amperage(ma) must be the same or higher.
And of course it must have the same plug with proper polarity if it is DC.
 
  #5  
Old 08-25-06, 08:39 AM
A
Member
Thread Starter
Join Date: Mar 2006
Posts: 124
Upvotes: 0
Received 0 Upvotes on 0 Posts
I finally found a place the has something close to what i need. Like I mentioned the one I'm replacing is 9v 500ma. The one I found is 9v 850ma. I read in the one post that the ma has to be the same or higher. Will this one be ok to use?? thanks
 
  #6  
Old 08-25-06, 08:50 AM
J
Member
Join Date: Apr 2006
Location: New Bern, NC
Posts: 1,530
Upvotes: 0
Received 1 Upvote on 1 Post
That should work, if the plug will fit, but if the device is under warentee, they will void it for using other than OEM parts.
 
  #7  
Old 08-25-06, 08:51 AM
M
Member
Join Date: Aug 2005
Location: USA
Posts: 919
Received 1 Upvote on 1 Post
Originally Posted by andy5150
I finally found a place the has something close to what i need. Like I mentioned the one I'm replacing is 9v 500ma. The one I found is 9v 850ma. I read in the one post that the ma has to be the same or higher. Will this one be ok to use?? thanks
Yes, if it is the right polarity. Some adapters leave the voltage as AC, others convert to DC. This is critical. If it is DC, just verify that the pins have the correct polarity as well, +/-.
 
  #8  
Old 08-25-06, 09:11 AM
A
Member
Thread Starter
Join Date: Mar 2006
Posts: 124
Upvotes: 0
Received 0 Upvotes on 0 Posts
I see what your talking about with polarity. The back of the unit under the ac input has a diagram on it. Negative symbol with a backwards c and then +. I assume this is the polarity you are talking about and the adapter has to have the same exact diagram on it. I checked out other adapters around my house and they are all different polarity. I never noticed that. Also my old and the adapter I might buy both have input ac and output dc on them. thanks
 
  #9  
Old 08-25-06, 09:49 AM
J
Member
Join Date: Apr 2006
Location: New Bern, NC
Posts: 1,530
Upvotes: 0
Received 1 Upvote on 1 Post
Talking

The C is really a representation of the outer shell of the connector. the part in the middle is the polarity of the center pin.

With DC this is very important. if you you get it wrong either it will just not work, or you will let the smoke out of the device.

If you let the smoke out, you are done. The smoke can only be put in at the factory.
 
  #10  
Old 08-25-06, 10:44 AM
A
Member
Thread Starter
Join Date: Mar 2006
Posts: 124
Upvotes: 0
Received 0 Upvotes on 0 Posts
great advice. I never knew about the polarity thing. I must have been very lucky in the past. I always went by volts and amps when switching adapters. Never even gave thought to the strange diagrams. Something else I noticed too is the diagram is stamped two different ways for the same center. Sometimes the negative symbol is on the left for a negative center with a backwards c and other times it is on the right with normal c and is also negative center. I guess this is just the preference of the company. thanks
 
  #11  
Old 08-25-06, 12:23 PM
A
Member
Join Date: Oct 2005
Location: Milwaukee WI
Posts: 1,217
Received 1 Upvote on 1 Post
Originally Posted by andy5150
Sometimes the negative symbol is on the left for a negative center with a backwards c and other times it is on the right with normal c and is also negative center. I guess this is just the preference of the company. thanks
If you want to get really confused consider two things:

Most cars in the US are 12VDC negative ground. The positives are fused and fed by a red cable from the battery + terminal. In a DC system, electrons flow out of the negative battery post and back thru the positive battery post. So positive ground would probably make more sense.

On the other hand, in a telephone central office (aka wire center) the battery system operates at -48VDC, which means the positive bus is at ground potential and the negative is HOT.
To further complicate things, in some offices the red wires are negative and the black wires are positive. However a lot of offices just have grey wires with tags telling you what they are carrying.
 
  #12  
Old 08-26-06, 12:31 AM
G
Member
Join Date: Oct 2004
Location: USA
Posts: 676
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by joed
The amperage(ma) must be the same or higher.
========
This statement is True if the power pack has a built in voltage regulator.
80 percent of the power packs don't have regulators, some-some items can be damaged by getting a higher current rating on a replacement power pack.
Power packs without voltage regulators, the current rating is more of a required load to bring down the voltage to a required specification.
If you don't know keep with the same rating of the original power pack, and that can be iffy.

http://forum.doityourself.com/showthread.php?t=219847


http://forum.doityourself.com/showthread.php?t=248540
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: