Laser pointer projection clock - Page 1
Forum section: electronics / projects

author: android
author_rank: Regular Contributor
timestamp: April 17, 2019, 11:43:26 pm
content: This is very much a work in progress...the idea is to use cheap red laser pointer diode modules from China to project the current time onto my bedroom ceiling when I wave my hand near the clock.The lasers would normally just produce dots on the ceiling but I plan to put some clear acrylic rod in the path to stretch each dot into a line. With a suitable mask and a bit of luck it should produce a readable image.I'm not even sure that it'll work at all but I've had fun laying out the PCB using KiCAD 5.1 on Linux - which I have to say is just amazing...so much so that I've shared a few shekels with the Kicad developers in appreciation. I used FreeCAD 0.18.1 to create the 3D model of the laser module - including a transparent lens.I'm going to use a PIC16F1455 to charlieplex the diodes.More updates after I start coding.Cheers,Andrew.

author: tggzzz
author_rank: Super Contributor
timestamp: April 18, 2019, 07:07:00 am
content: Glad to see the silkscreened warning!How do you plan to ensure there arenever"unfortunate" specular reflections?Failure mode analysis can be fun, as well as essential!

author: Spirit532
author_rank: Frequent Contributor
timestamp: April 19, 2019, 07:06:08 am
content: A bit of advice:Buy genuine,properly ratedlasers that are guaranteed eye-safe, both in class and in power. They won't cost you a lot more in this sort of quantity(dozens including spares/"oopsie" insurance, not singles), but you can be sure that you won't get eye damage from accidentally looking at it.Plus, the beam will be more stable and nicer looking.

author: Gyro
author_rank: Super Contributor
timestamp: April 19, 2019, 10:18:17 am
content: I don't think you need the lasers. Projection clocks normally just use an led backlit small lcd and a lens. it really doesn't take much light to project in a dark room. You can keep it on constantly then.Youdowant to get to sleep at night don't you?P.S. The original version of this just used a small torch bulb, lens, Fob watch hung on a hook, and a 45' mirror.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 19, 2019, 05:01:37 pm
content: Just recently I thought about a similar project.The Idea was to use 2 slots. A vertical slot an a horizontal slot, and then position line laser modules between the slots to cap the sides of the line laser modules.There is no need to position the lasers themself in the same orientation as the 7-segment displays, you just have to point them in the right direction.Best way to design it is probably in a 3D CAD program, and then use a 3D printer to print a piece of plastic to keep the orientation of the lasers correct.Instead of charlieplexing I wouls probably also use a LED driver IC that does the multiplexing for me.Then I looked up the price of line laser modules, did some calulations and decided to abandon the project.

author: floobydust
author_rank: Super Contributor
timestamp: April 20, 2019, 04:31:15 pm
content: You can use an LED or VFD display with an old camera or slide-projector lens. That works fine in a bedroom.Using lasers, I would put them on a propeller clock using an old VCR head drum.

author: james_s
author_rank: Super Contributor
timestamp: April 20, 2019, 06:27:21 pm
content: You don't *need* lasers but it does sound like a cool idea and they're certainly cheap enough. I remember drooling over the first visible red diode lasers back when they were around $250 each and thinking it was so amazing they could fit an actual laser into something the size of a flashlight.