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500mA or 1A ? Does it really matter?
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| magicsid |
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Posts: 12
Joined: 19 Apr 2008
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Posted: Tue Jul 01, 2008 3:23 pm
Post subject: 500mA or 1A ? Does it really matter?
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Tittle says it really..
If a camera is for example 300mA..
And you power it with a 1A power supply... will this damage the camera?
Maybe a daft question but there is many suppliers that give you a 1A power adapter as standard with cameras.. Is this safe to use ??
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| alanjh1965 |
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Posts: 97
Joined: 03 Nov 2005
Location: London
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Posted: Tue Jul 01, 2008 3:41 pm
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In Simple Terms.......
If you need $300 to buy something and you take $1000 with you, you only need $300 but you have something in reserve !
It's the same when powering Camera's, althought the Camera only draws 300ma from the 1000ma (1amp) supply leaveing 700ma spare it is always better to over engineer your power supplies.
The 1 amp won't damage the camera !
Simple !
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| magicsid |
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Posts: 12
Joined: 19 Apr 2008
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Posted: Tue Jul 01, 2008 3:50 pm
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Ok
I dont think i agree, i think over powering ANY electrical item with a larger supply is not the safe way to go in my experiance, But as were only talking about mA here i wasnt sure if the current was going to make a damagable difference!
I didn't think it would.
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| kensplace |
Moderator
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Posts: 929
Joined: 30 May 2006
Location: UK
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Posted: Tue Jul 01, 2008 4:08 pm
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If a camera draws 300ma on a 500ma supply, it will draw exactly the same 300ma from a 1a supply, or a 2a supply...
A power supply that can provide more amperage will just have extra unused spare capacity compared to a equal one with a lower amperage..
Using a bigger amperage PSU will in no way 'force' more amperage into the camera.....
The only exception would be in a fault condition, such as a short, or a faulty camera, in which case the more amperage the psu can supply, the more damage can occur.....
Best bet would be to install a suitable fuse if your power supply amperage is much bigger than the needed amperage for the device, so in a fault, the fuse blows.
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| cachecreekcctv |
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Posts: 372
Joined: 11 Nov 2005
Location: California (Northern)
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Posted: Tue Jul 01, 2008 5:36 pm
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The amount of power your camera, PTZ, etc. draws is based upon resistance of the device . Just remember 1 amp, when dealing with 12vdc is not much VA's. Common misconception is that electricity is "pushed" into a motor, camera, etc. Not so. I myself always try to use a much larger Power Supply than is called for. One big reason is heat. When I build my own power supplies for large jobs, I normally use a 9 to 15 amp Sola (manufacturer) power supply. With my ampmeter, I can actually check on the "amp draw" of my project. "MA" or Milliamps are also sort of deceiving. One thousandth of an amp is hard to distinguish, when you have a camera (or other decvice) pulling 300 MA, and another pulling 500ma. Power supplies generate a lot of heat when rectifiing AC to DC. Also lose a little bit on the supply end, in terms of overall power supplied.
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| ak357 |
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Posts: 294
Joined: 16 Nov 2005
Location: Canada
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Posted: Tue Jul 01, 2008 6:05 pm
Post subject:
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| cachecreekcctv wrote: |
| Power supplies generate a lot of heat when rectifiing AC to DC. |
not really
heat is being generated only by drawing current 
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| mcs |
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Posts: 301
Joined: 07 Jul 2004
Location: Austie
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Posted: Tue Jul 01, 2008 9:05 pm
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I also, do overspec my power supplies on jobs, if it requires 2 amps I use 5, if it requires 1 amp I use 2...
As long as its regulated power supply youll be ok,
Does not affect the camera unless its rated @ 12vdc and your giving it 13.8, check
Always FUSE your pos + connection @ the power supply, although most p/s's have internal fuse it dont hurt to fuse it, saves a possible fire.....
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| Lolo Wolf |
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Posts: 424
Joined: 18 Jan 2007
Location: Northwest Montana
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Posted: Wed Jul 02, 2008 12:34 am
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Heat is released in three ways: conduction, convection, and radiation and all power converters - AC/DC, DC/DC and DC/AC consume power that is dissipated internally as heat."Heat" must be removed from power-dissipating components within a converter in order to stay within a functioning temperature as well other critical components keeping to a stable constant temperature. The Arrhenius equation for reliability indicates a power device failure rate increases 3 to 5 times for a 25°C rise in temperature. Its a good idea to bench all power supplies and check their specs/rating prior to applying in the field. Most failures Ive come across are from improper wire practice cable management and power related camera malfunction due to "plug a play" attitude that some "professionals" as well DIYers have when working with circuits (all voltage)
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| Smit9352 |
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Posts: 251
Joined: 14 Feb 2008
Location: Louisiana
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Posted: Wed Jul 02, 2008 9:43 am
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| mcs wrote: |
I also, do overspec my power supplies on jobs, if it requires 2 amps I use 5, if it requires 1 amp I use 2...
As long as its regulated power supply youll be ok,
Does not affect the camera unless its rated @ 12vdc and your giving it 13.8, check |
I agree, I've always had customers get 1amp even for 300mA and 500mA applications because you're never 100% sure of the distance that customer is going to run and if there will be a power/voltage drop over the said distance.
I like to be over not under
We now have all of our power supplies here as regulated so now there's no problem with using something larger than necessary as the camera is only going to draw the mA it needs to function properly.
Thanks,
John
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| Kiwi |
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Posts: 252
Joined: 03 Sep 2007
Location: New Zealand
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Posted: Wed Jul 02, 2008 5:18 pm
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You're not suggesting extra current capacity directly accommodates longer wire runs...?!
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| survtech |
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Posts: 673
Joined: 21 Mar 2007
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Posted: Wed Jul 02, 2008 5:46 pm
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| Kiwi wrote: |
| You're not suggesting extra current capacity directly accommodates longer wire runs...?! |
You could make a case for that with a non-regulated supply, ie. 24VAC, since the higher current transformer would not load down quite as much.
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| cachecreekcctv |
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Posts: 372
Joined: 11 Nov 2005
Location: California (Northern)
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Posted: Wed Jul 02, 2008 7:02 pm
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A power supply that is not drawing current is not being used. Next time you find a working power supply, near its' rated capacity, and it is cool to the touch, please let me know. I work with DC power supplies all day long. Mostly in the 90VDC to 480VDC range. 12VDC CCTV power supplies are about the most simple I have ever installed. Always try to use a larger capacity power supply, and do your best to keep it cool.
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| cocacola |
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Posts: 123
Joined: 12 Feb 2008
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Posted: Thu Jul 03, 2008 3:53 am
Post subject:
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| alanjh1965 wrote: |
In Simple Terms.......
If you need $300 to buy something and you take $1000 with you, you only need $300 but you have something in reserve !
It's the same when powering Camera's, althought the Camera only draws 300ma from the 1000ma (1amp) supply leaveing 700ma spare it is always better to over engineer your power supplies.
The 1 amp won't damage the camera !
Simple ! |
Ok, i get i!
In my case my bosh camera is 12 Volts, but my power course is 48 volt... so i have no problem here, and still 36 volt as reserve.
Gonna plug it in now...
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| Kiwi |
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Posts: 252
Joined: 03 Sep 2007
Location: New Zealand
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Posted: Thu Jul 03, 2008 6:10 am
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I think after tossing the grenade into the room, the original poster has long left...
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| magicsid |
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Posts: 12
Joined: 19 Apr 2008
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Posted: Thu Jul 03, 2008 7:04 am
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lol, No im still here! just reading the posts. I take it i was wrong, I must be thinking of the wrong volt input being dangerous.
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