HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Blogs
Gadget Freak

Gadget Freak Case #272: Motion Sensor Light Switch

NO RATINGS
1 saves
View Comments: Newest First|Oldest First|Threaded View
Nugent_56
User Rank
Gold
Re: Motion Sensor laser power
Nugent_56   9/3/2015 1:05:13 PM
NO RATINGS
Very nice! Thankyou for the detailed reply!

wgrill
User Rank
Iron
Re: Motion Sensor laser power
wgrill   9/3/2015 12:44:12 PM
NO RATINGS
the common red laser is readily available.

The laser is PWM modulated to reduced the power and also varied depending on whether the laser is detected or not detected. The power to the laser is also a bit reduced because the voltage delivered to the laser module incudes some small losses from controllers driver and in the cabling to the laser/photo detector module.  There are also a few other driver features that provide 'debounce' delays between hand swipes so as to distnguiish the hand motions. 

I found that for long light path lengths the laser power will likely want to be greater/ brighter because the detected light is more dispersed over the longer path. This can be adjusted at the regulator or by shorting 1 of the the 2 diodes shown in the regulator related schematic.  

Nugent_56
User Rank
Gold
Motion Sensor
Nugent_56   9/3/2015 10:57:16 AM
NO RATINGS

So I understand the principal operation is a beam interruption with some smarts behind it. Two questions: Why did you choose a visible red laser beam rather than an invisible IR LED? Second, as I understand it, laser pointers are not meant for continuous operation due to internal heating. Did you take any steps to keep the laser cooled to prevent its early demise? Thanks RW

Partner Zone
More Blogs from Gadget Freak
Portable Electronic Weather Evaluator (PEWE) is a weather station equipped with multiple sensors for gauging temperature, wind speed, barometric pressure, and altitude.
The Attack Dyno brings car enthusiasts an attack timer and dynamometer in a small, portable package with the ability to output vehicle torque, speed, horsepower, 1/4 mile times, 0-60 mph acceleration times, ambient air temperature, and more.
The Leaky Tree is a high-quality device designed to dispense ice and one of four mixed drinks that can be selected by the user.
The Handy Rival is an arcade game that allows an individual to play rock, paper, scissors against a robotic hand.
Design News Webinar Series
8/13/2015 11:00 a.m. California / 2:00 p.m. New York
6/25/2015 11:00 a.m. California / 2:00 p.m. New York
6/24/2015 11:00 a.m. California / 2:00 p.m. New York
9/10/2015 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Aug 31 - Sep4, Embedded System Design Techniques™ - Writing Portable and Robust Firmware in C
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Course August 25-27:
Sponsored by MICROMO
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2015 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service