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

jjonas's bookscanner

Built a scanner? Started to build a scanner? Record your progress here. Doesn't need to be a whole scanner - triggers and other parts are fine. Commercial scanners are fine too.
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jjonas

jjonas's bookscanner

Post by jjonas » 12 Jan 2012, 08:57

Hi,

I've been scanning books for some years with a flatbed scanner, but recently I found this forum when I had been googling around for information on the IonAudio BookSaver (RIP) and started building my own DIY model even when the news of the BookSaver product termination had not been confirmed yet. So for the benefit of the audience here and to congratulate myself for work well done, here's a few pics.

1. First off here's the whole thing. I don't remember which/whose design(s) I used as the basis for this, but naturally it was somewhere here on the forum. The PSU I use for the cameras and remote triggering is also modified based on a link I found here. The materials (including the cameras, 2nd hand) cost about 130€. The platen is "foldable", the sides are attached to each other with (semi)transparent duct tape at the corners. I don't know how long that will last, but given that I'm not scanning on an industrial basis, it might be an ok enough solution even in the long run; certainly it's easier to turn the pages with this than with a platen with the sides in a fixed angle (tried that too).

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2. Here's the adjustment mechanism. It's with a wingnut, which is not so clear offhand with the angle here.

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3. The electrical stuff comes in and leaves here. It includes an option for 12VDC, though I'm sure I'll need it.

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4. Remote trigger and encasing (just a 60x60mm bit of bent 1mm metal).

Image

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daniel_reetz
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Re: jjonas's bookscanner

Post by daniel_reetz » 12 Jan 2012, 15:06

Love the compactness and simplicity of your build. Have you had any issues with your PSU? One of our members recently had some problems trying to get one to work.

Can you describe your page-turning process a little? Vari-angle platens are a rare thing around here and I'm definitely interested in hearing more about them.

jancoj
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Re: jjonas's bookscanner

Post by jancoj » 12 Jan 2012, 16:59

I am interested in PSU as well. How does it work? Could you share more info? Thanks

jjonas

Re: jjonas's bookscanner

Post by jjonas » 13 Jan 2012, 02:38

@daniel: There's been no issues with the PSU this far, though it's also true that apart from testing I've scanned only one book with it. But I don't see any reason as to why it should fail once it's working. I bought two PSUs from the local recycling centre 6€ apiece, I thought I'll modify the other one into a general purpose "bench PSU" for electronics projects, but found one of them wasn't working; apparently there was a fried component (judging by the black dirt around some diodes), but I didn't investigate it further.

Page turning with the foldable platen works so that after taking a shot I fold the platen (turn the right side on the left), lift it with one hand and turn the page with the other. Then I put it back on the book. The main reason I did it like this is that lifting a fixed-angle platen would have required that I put the cameras more apart so that there's enough room to lift the fixed platen without having to worry about it hitting the cameras.

Possible downsides are perhaps that with small books the 20cm x 30cm platen tends to rise a bit in the middle, so that you have to hold it lightly in place by hand. I haven't found that too inconvenient though, because you only need one hand to operate the trigger, so the other is free to do whatever in any case.

I scanned the first book with it yesterday, 200 pages took 15 minutes, I'm pretty happy with the rate. The book itself BTW was printed in fraktur, but running it through Tesseract 3 + VietOCR with German Fraktur as the language setting produced relatively good results (not significantly worse than the usual OCR output for Finnish).

@jancoj: I modified the PSU as per the instructions here: http://web2.murraystate.edu/andy.batts/ ... SUPPLY.HTM

The modification process is relatively simple (then again I'm an electrician), because the PSU supplies the needed voltages (3,3VDC and 5VDC) out of the box. Basically you just have to connect a 10W / 10 Ohm resistor between one of the 5VDC-GND wire pairs, and connect the POWER-OK wire to another GND wire. Normally POWER-OK is connected to GND through its being connected to the motherboard, so in this case it has to be fooled into thinking it's connected to it. (What the different color wires were was written on the side of the PSU). The modification instructions said that the PSU needs the 10 Ohm dummy load in order to work. I didn't try whether it really needs it - the resistor was only 1€, so I didn't see a point getting possible trouble by trying to save the money, and no doubt the original author of the instruction was better informed as to the functioning of a PC PSU than I am.

I lowered the 5VDC with a diode which lowers the voltage 0,6V (but does nothing else in this setting), because the CHDK wiki emphasised that the USB trigger pulse should be no more than 5VDC (http://chdk.wikia.com/wiki/USB_Remote_Cable).. the actual voltage put out by the PSU was 5,2VDC or something, so even though in practice it might have made no difference, I decided to play it safe as the trick is relatively simple, because the wiki did say (http://chdk.wikia.com/wiki/CameraFeatures) the needed pulse is somewhere between 3,5 and 4,5 VDC.

For powering the cameras I used the 3,3VDC without modification (or regulation), even though the nominal is 3,15 VDC.. I judged that was within tolerance. Maybe digital cameras are more refined electronics-wise, but in my general experience electronics work with voltages that can deviate a lot from what the nominal voltage is (see e.g. http://hackaday.com/2012/01/04/exposing ... ue-prices/, which actually deals with digital cameras.. the "DC" at 2:16 - what a load of rubbish! :'-D ). Most probably the 3,15VDC nominal is there because Class I DC plugs have 3,15 VDC nominal maximum.

I haven't measured how much current the cameras draw from the PSU, maybe I could do that at some point.

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Re: jjonas's bookscanner

Post by rob » 16 Jan 2012, 12:08

jjonas wrote:Maybe digital cameras are more refined electronics-wise, but in my general experience electronics work with voltages that can deviate a lot from what the nominal voltage is (see e.g. http://hackaday.com/2012/01/04/exposing ... ue-prices/, which actually deals with digital cameras.. the "DC" at 2:16 - what a load of rubbish! :'-D ).
That was definitely one of the funniest and yet informative videos I've seen in a while. I was totally amazed to see that the camera actually worked with that kind of power output.
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