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measuring ac adapter

chi1

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measuring ac adapter

Postby mik000000 » June 21st, 2012, 9:44 am

i have 3 9v ac adapters in my spares bin. i have measured all 3 at between 12v and 12.6v. am i measuring incorrectly?
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Re: measuring ac adapter

Postby Yoga Flame » June 21st, 2012, 11:19 am

If you suspect your multimeter is not accurate, measuring a 9V battery is an easy way to confirm.
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Re: measuring ac adapter

Postby mik000000 » June 21st, 2012, 11:23 am

meter is ok. i checked with a meter from work as well. do i need to have a load on the output to gte an accurate measurement?
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Re: measuring ac adapter

Postby linux-works » June 21st, 2012, 11:36 am

yes! you often need a load.

the voltages can be crazy high. a 5v can read 7 or 9 or even 10, sometimes.

ac adapters are less critcal as there will be a dc and regulation stage later. a dc adapter should be the right voltage but so many assume a further-down regulator in the circuit and so they cheap out. I hate that but its quite common and you should always measure it unloaded (to see how bad it can get) and then loaded with a safe load. still, if its higher than it should be, unloaded, just don't use that one.
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Re: measuring ac adapter

Postby mik000000 » June 21st, 2012, 11:39 am

thanks
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Re: measuring ac adapter

Postby MisterX » June 21st, 2012, 11:53 am

do i need to have a load on the output to get an accurate measurement?


No.
The instructions do not mention loading the output (when testing the output voltage) because a regulated AC adapter is specified. ;)



2.Check the AC adapter's output voltage. Leave its DC output plug unconnected, and plug the adapter into an AC outlet. Set your multimeter to DC V mode and measure the voltage at the output plug. Place the black probe on the outer conductor and the red probe on the center conductor, taking care not to short circuit the two. In order for the adapter to be used with the χ1, the reading must be between +8.85V to +9.25V. If this requirement is not met then do not use it.
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Re: measuring ac adapter

Postby amb » June 22nd, 2012, 12:22 am

What MisterX said. I should emphasize that the adapter must have REGULATED 9V DC output. Too much voltage will cause the χ1's charging chip to overheat and derate, and too little voltage will cause the LiPo cells to not charge fully.
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