We needed a wall clock… After moving to a fresh renowned new rental, we weren´t allowed to drill a wall clock in the bedroom. Then came the idea to build a projector clock, based on Arduino, LED light, Nokia LCD, and a DSLR lens :D
This article is about a beta-version stuff, which has several mistakes built-in; but the concept, the schematic, and software may be useful for anyone building any similar :)
The core idea was that if you lit a bare (only the glass) LCD, and conduct light through a lens, you get picture on the wall. Hm, that´s a tiny projector :) I had a faulty Sigma 75-300 f4-5,6 APO DG lens (bought for parts for my similar one), which was perfect for this.
I made several mistakes during building, so it is finished as a beta version, which is usable, but way not perfect. I have chosen a too small box for it, and had room for LED only under the LCD – bad idea, the 4-500lm 4W LED is too hot (ehm, seemed not so hot during testing… and note that in the beginning, this was planned to a night-only clock, then girlfriend forced to be readable during daytime… :D ), heats up the LCD, which becomes unreadable when it is warm. So a fan needed, with control.
The fan and brightness control was made with simple transistor switches. The bayonet for lens is made from a lens rear cap, while the housing, with the LCD mount from plastic (LCD can be positioned in every directions). This part is also not a perfect work, but i had no room due to small case. However, LCD is stable, does not move.
So the “final” thing is working like :
– adjustable picture size (zoom lens :D )
– adjustable behavior for dark and bright places (e.g. night time, room lamp is turned on, or sun shining through window – a light sensor is also used)
– fan control, for dark situations fan stops (lower brightness is enough)
– image can be inverted
– screen can be rotated with 180 degrees
– has an on-screen menu for adjustments
– small size (too small :D )
– sleep mode with one-button
– the image size on 300mm is 25-30cm on the ceiling, and brightness is enough to be readable with room lights turned on
The other hand : this stuff is ˜50% made out of recycled stuff. The LCD, the lens, the box, all was considered as rubbish.
Iˋm preparing for next version, based on ESP8266, with Wi-Fi, NTP, and larger housing, allowing the LED placed away from LCD. (Or using laser… ^.^ )
I’ll make the software & source downloadable when i finished tidying it :D (Or you can rquest it by mail, an i send it as it is now.)
Okay, not a world class image, but this is the result – upside down, as it’s readable when you’re inside the room or lying on bed.
The device itself with a Sigma 70-300 APO DG telephoto lens
LED, LCD holder parts, and LCD in place, with LCD wiring
Testing with parts outside
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