Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

do i really need a voltmeter?

Everything camera related. Includes triggers, batteries, power supplies, flatbeds and sheet-feeding scanners, too.
tsttm
Posts: 80
Joined: 18 Jun 2009, 11:59

Re: do i really need a voltmeter?

Post by tsttm » 24 Jul 2009, 10:33

in that case, i might just return my defective multimeter, period. i can't see myself using one of these again..if i do, i'll take the time to hunt a cheap one off ebay.

The cables of my usb hub has a 5th wire- from left to right, it's red, white, green, black, and then a thicker black. on closer examination, i can see that the 5th, thicker black appears to be a bare wire with only the insulation covering the wire from when the bare wire exits the clear cable (whice envelops all 5 cables) to the insertion to the circuit board.

Is the 4th black my ground? I'm assuming my red follows the convention & is positive.

thanks!

tsttm
Posts: 80
Joined: 18 Jun 2009, 11:59

Re: do i really need a voltmeter?

Post by tsttm » 24 Jul 2009, 10:42

Image

ps, if i decide to use that diode thingy just in case...how do i use it to test polarity? i didn't understand that part. it sounded like you were saying you could use it instead than a multimeter...but do you use in conjunction with a multimeter? how's it going to tell me polarity?

Turtle
Posts: 40
Joined: 04 Mar 2014, 00:53

Re: do i really need a voltmeter?

Post by Turtle » 24 Jul 2009, 11:10

The cables of my usb hub has a 5th wire- from left to right, it's red, white, green, black, and then a thicker black. on closer examination, i can see that the 5th, thicker black appears to be a bare wire with only the insulation covering the wire from when the bare wire exits the clear cable (whice envelops all 5 cables) to the insertion to the circuit board.

Is the 4th black my ground? I'm assuming my red follows the convention & is positive.
Great that you ask about the fifth wire. I left that out intentionally because I thought most wouldn't use it. The fifth wire is chassis ground or equivalent of ground except that it' s bolted to the chassis of your gadget. You hook this fifth wire to ground and/or to a steel part of your book scanner. This prevents static electricity buildup and help in other ways too. And yes, the fourth black wire is ground.
chasground.jpg
chasground.jpg (4.73 KiB) Viewed 3346 times
if i decide to use that diode thingy just in case...how do i use it to test polarity? i didn't understand that part. it sounded like you were saying you could use it instead than a multimeter...but do you use in conjunction with a multimeter? how's it going to tell me polarity?
In order to use a diode to check for polarity of a power supply (a power adapter that you've spliced and you don't know the polarity) you simply hook up the white tip (or stripe) side of the diode to the red wire of the USB wire (the one that goes to your camera.) Then hook the other side (the black side) of the diode to one of the power supply wire. Finally, hook the black wire of the USB to the other power supply wire. After that, you will check to see if your gadget worked. If not, then swap the power supply wires, but keep the diode attach to the red wire always as you swap the wires in different combination. Once you have it all working you can remove the diode and keep it as a handy polarity checker.

If you have a light bulb or a flashlight you can hook the diode to that to test (highly recommend.) Just put the white tip of the diode to the bulb then hook the wires in combination until the bulb works. When it works you know that the white tip side is the positive side.

Karyudo
Posts: 35
Joined: 14 Jun 2009, 01:51
E-book readers owned: iPod Touch
Number of books owned: 0
Location: Vancouver, Canada

Re: do i really need a voltmeter?

Post by Karyudo » 25 Jul 2009, 01:41

@tsttm: Hey, fellow Canuck. If you haven't already, try Princess Auto! http://www.princessauto.com/tools/autom ... multimeter

tsttm
Posts: 80
Joined: 18 Jun 2009, 11:59

Re: do i really need a voltmeter?

Post by tsttm » 25 Jul 2009, 12:01

hey thanks,

i just hoped they color (colour for my fellow canuck) coded the wires correctly & went for it. Sure enough, the hub light went on & the cameras fire.

But, now i'm having a hell of a time soldering..i left it to the last step & i feel like my whole project might hit a wall right now because of it.

I'll start a new thread, maybe i can get some tips on soldering.

thanks!

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daniel_reetz
Posts: 2786
Joined: 03 Jun 2009, 13:56
E-book readers owned: Used to have a PRS-500
Number of books owned: 600
Country: United States
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Re: do i really need a voltmeter?

Post by daniel_reetz » 25 Jul 2009, 12:05

You don't need to start a new thread to learn how to solder. Just head over to YouTube.

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