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Connecting Canon 40D USB disables laptop!

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#1 Tonk

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Posted 04 April 2013 - 09:41 AM

Has any one come across this. I was powering my Canon 40D in the following configuration. Car (12 volts) - Belkin 12v DC to 240v AC -> 240v to 8 volts power unit (not Canon but compatable) -> Canon 40D. Tnen Canon 40D via USB cable to Dell Vostro laptop. In this configuartion the mouse cursor locks up and can't be used. Disconnect the USB cable at any time and all is OK. Put battery in camera as opposed to external AC unit and all is OK.

There is obviously interference going on - does anyone know what it might be or how I can find out.

I still have a couple of experiments to do - e.g. wall socket 240 AC to camera power unit to eliminate the Belkin inverter etc. I'm trying to narrow it down to either the Belkin inverter OR the aftermarket camera AC adapter or both in combination

Anyway this stoped me fine focusing the camera/lens while up a mountain last night trying for PanSTARRS :(

#2 Footbag

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Posted 04 April 2013 - 09:56 AM

I just got mine solved, but it must be the week of odd problems.

You know what to do. Start with the setup that was causing the problems and then remove one item at a time until the problem disappears. Then make sure you can reproduce the problem with the bad cable, part, etc... Then remove and replace it.

When the mouse cursor freezes, can you still use the keyboard? IE Everything works but the mouse cursor?

#3 Mike Clemens

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Posted 04 April 2013 - 11:03 AM

That's a weird one. You'd think the Belkin unit would isolate things? I'd measure for DC voltages between computer and camera ground. Maybe a cheap non-powered hub between the cam and the computer would somehow break the voodoo spell. Maybe reverse the AC plug that's plugged into the Not-Canon adapter.

#4 Tonk

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Posted 04 April 2013 - 11:10 AM

remove one item at a time until the problem disappears


Yeah done that - but that removes the bits I actually want to use - power camera from car, and use laptop to focus. Just checked the cables - they are all OK especially the USB cable. My Canon 450D and same laptop work OK with the USB. The Belkin inverter works- used it for years. The AC camera adapter works - beeing running the camera last 3 nights OK.

So whats left is something on the signal or voltage lines - thts my guess. Wonder if the voltage on the USB fitted to the camera while being powered via the inverter is too noisy or something related ??

I can solve via a work around - put battery in camera when focusing, then switch over to AC adapter for main image run

#5 Tonk

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Posted 04 April 2013 - 11:14 AM

I could eliminate the Belkin inverter/AC adpater if I could use a circuit to run the camera off the car battery - requires dropping 12 volts to 8 volts - anyoine know a good efficient circuit with safeties (8 volt output clamping etc)

#6 snowcrow

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Posted 04 April 2013 - 12:35 PM

This might work for you. Not sure if you have a plug on the foe battery end, but you can always do some customizing. Just make sure the polarity is right.

#7 Tom and Beth

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Posted 04 April 2013 - 01:38 PM

Tonk,

About two weeks ago somebody mentioned building a step down circuit using this

I bought this one

While I haven't used mine yet in the cam, I have similar ones with fans and such. Yes I'm well aware fans are less demanding than a Camera, but...

#8 Mike Clemens

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Posted 04 April 2013 - 01:58 PM

A switcher P/S like that might be a bit noisier than a linear. If you're going to start soldering things, I'd just get a 7808 DC positive linear regulator. A bit warmer than the switcher but clean and quiet.

#9 Phil Sherman

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Posted 04 April 2013 - 02:41 PM

I'm using one of the little switching regulators mentioned by Tom and Beth to power my Canon camera and have no problems. I did add an additional filter capacitor on the output of the regulator to help add some additional noise filtering.

At 12V in and 8V out, a linear regulator will be around 67% efficient, dissipating around 1/3 of the power drawn from the battery as heat. Switching regulators usually run around 90% or higher efficiency easing the battery load. The difference for the camera at 8V isn't a lot but if you're generating 5V for USB stuff, the numbers become really nasty. For 5V, over 58% of the power drawn from the battery is dissipated as heat. Switching regulators go a long way to adding to your battery life.

You're not only limited to buck regulators. There are also buck/boost units that will output a fixed output in the 12-14V range with input voltages as low as 10V. I ended up using one for my mount to prevent it from complaining at the end of a long night, when battery voltage was at its lowest.

Phil

#10 Jerry Lodriguss

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Posted 04 April 2013 - 06:45 PM

I could eliminate the Belkin inverter/AC adpater if I could use a circuit to run the camera off the car battery - requires dropping 12 volts to 8 volts - anyoine know a good efficient circuit with safeties (8 volt output clamping etc)


This is the best one I know of:

http://www.easternvo..._8vsupply01.pdf

Jerry

#11 zerro1

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Posted 04 April 2013 - 07:09 PM

Tonk, I purchased an "Astronimiser" (The pro version is the one I got as it has a built in protection for voltage) from the UK... It's got the cig lighter plug in. I find it completely trouble free!

#12 Mike Clemens

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Posted 04 April 2013 - 07:34 PM

How is the laptop powered?

#13 Tonk

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Posted 05 April 2013 - 01:44 PM

How is the laptop powered?


Internal battery

Ok thanks everybody this has been very helpful. I think I'll start off looking into Astronomiser stuff - its easy to get in the UK and I've bought from them before but had not realised they do car -> camera power converters

#14 Mike Clemens

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Posted 06 April 2013 - 03:52 PM

Weird, Tonk... with the laptop on internal battery you'd think it would just float wherever the car voltage was and everything would be happy.






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