DIY Book Scanner

btw, that behavior might be consistent with an "audio taper" pot or a "log" pot. I'll try it on my own setup as soon as I can.

I was using the 1.7amp PSU, I'll try the 3 amp tonight.

Also, I think I'd be just as happy with a off-med-full setup. Off could be a switch on the PSU to the buckpuck, and full would just be a switch (I think if there's nothing/open switch between ctrl and ref you get full bright, twist them together/closed switch no light at all?). I like the idea of having a "working brightness," enough to turn the pages and get ready, and a "capture brightness," full I guess, so I'll try a few different resistors like you said.

Please tell me if the following makes sense, realizing the resistors could be swapped out until they add up to 5k ohms which would be full anyway:

Two levels (med-full):

Low beam:
ctrl--->closed switch--->1k ohm resistor--->ref

Full beam, open switch.

Three levels (low-med-full):

Low:
ctrl--->closed switch--->1k ohm resistor--->closed switch------------->ref
.................................................--->2k ohm resistor-----------^

Med:
ctrl--->closed switch--->1k ohm resistor--->OPEN switch------------->ref
................................................. --->2k ohm resistor-----------^

Full beam, open first switch.

here's how i am imagining this thing

That's much nicer. Depending on traffic and inlaws, I'll have it done tonight.

I have now tried 1K ohm and 3.3K ohm resistors and still only get dazzling or blinding, no real reasonable work light intensity. I'd appreciate anyone else with home made LED set up see how low will they go. I'll also call LED supply tomorrow and ask what I should expect.

Edit:

I think I ought to go play with the wooden parts again. I've had enough of these electrical bits.

I'm gonna get my buckpuck-powered rig out and experiment now. I'll post back here with results.

Alright, so I just checked the circuit out with a 10k pot (just what I had laying around). I'm going to post a video in a minute (UPDATE: about an hour, blasted slow uploads!), but the lesson learned is that values around 250-500ohms are where the dimming happens. As a result, the total dimmable area available to you on a 5 or 10k pot is very small. You can try some small-value resistors, or a 1K pot (so that the 300-500 range comprises more of the available turning radius of the pot) to get down to the values you're looking for.

Daniel:

Earlier in this thread you showed a photo of two lever switches with rollers. I'm sure that one was to control the low-high levels of the lights. What was the purpose of the second switch?

Thanks

The second switch is to trigger the cameras for the system described in this thread.