A project log for Project Photobooth

Current cost: under $50

Sarah WittmanSarah Wittman 04/02/2014 at 04:160 Comments

Sorry for the broken photos in the previous logs. They should be fixed now. Turns out, if you upload from desktop-dropbox, Hackaday hosts the images, but if you upload from web-dropbox, the images continue to be hosted by dropbox. I could see them because I was logged in.

I've been holding out on acquiring lighting until I had a chance to see Costco's RGB LED kit. I plugged it in and did some color tests. It looks great and is incredibly bright. I think it will make for some nice pictures! For some reason, drobpox only autograbs photos from my phone and not video, so I'll have to upload these manually.

The kit includes a wall-wart/remote combo to control color. The colors share a common positive terminal with separate negatives for each color. Probing these terminals with a multimeter showed something I wasn't expecting. When changing the  brightness of each channel for a particular color, the brightness is controlled by pwm. However, when changing the overall brightness of all 3 channels, the positive rail voltage changes, ranging from 4 to 12V.

Actually, now that I think about it, that makes sense.

Point being, pwm is bad, because it really messes with cameras. I'm looking to build a small control circuit in the next few days to change each color channel's current, rather than PWM. This will make it play nicer with cameras. This should be a really simple circuit, using large potentiometers as voltage dividers.