Thanks to the MSP430 used inside, In this video I calculate the MS6612 light meter should get up to 470 hours of continuous usage.

August 27th, 2009

Bicycle Tail Light

Bicycle tail light

You want to learn more about DC to DC boost converters? Here is a good and practical application of such converters, an LED tail light for your bicycle. Why do you need a boost converter for that you might ask, when you can simply have a battery power up some LEDs. Well, this way you greatly increase efficiency, you increase the number of LEDs you can drive and thus increase the perceived power of light. And yes, you will learn about them.

This project makes use of the National Semiconductor LM3410 chip. This chip provides a current regulation rather than a voltage regulation and makes it suitable when working with LEDs. This current regulation is done by switching a NMOS gate at constant frequency of 525Khz ( you can also chose 1.6Mhz) and varying the duty cycle, the so called pulse width modulation. Given a constant frequency varying the pulse width results in varying the mean value in time. The regulation is done by providing a feedback current that causes a voltage drop on a resistor which in turn is fed into a comparator.

The output of this comparator goes to the PWM comparator where it faces the output of the amplifier that reads the switched current through an inductor. The result will be a PWM signal attacking the NMOS gate and thus providing a steady mean output current value. The current sensing amplifier also provides an output for switched current limiting. Some nice features of LM3410 makes things easier, it’s internally compensated,  has a very low stand-by current, has dimming possibilities and thermal shutdown.

As the author states in his article you have to be careful when choosing components. Since the operation frequency is pretty high the diodes through which the inductor discharges must be high speed or you risk blowing the chip. Taking things a step forward he added a PIC12F683 microcontroller to provide some light effects selected by a pressing a button.

If we look closer at this project we can see it can be further developed, using the dimming possibility of LM3410 you can also turn it into a stop light. Whenever you break light intensity goes higher. Another development is to adapt it to be used with a dynamo. Have fun.

Bicycle Tail Light: [Link]

July 20th, 2008

Light Detector Application

Light Detector Application

This application explains how to make a light detector for ARobot. This can be used to tell when a light is on or off, whether the robot is inside or outside, or for light following. This is a simple expansion and does not require soldering if using a breadboard.

It does assume that you have attached a breadboard and an expansion cable to the ARobot . This circuit and the light sensor could be mounted and soldered to a perf board and located to a movable head. Multiple light detector sensors could be used to detect the direction of light.

Light Detector Application: [Link]

Wireless Controlled Lightdimmer Using TV Remote Control

The goal of this project was to build a normal dimming lamp that is also controlled wireless with a tv remote control. When you switch the power on there will follow a soft-start till the lamp burns at the previously adjusted dim level. With the P+ and P- button from a system at choice you can adjust the maximum and minimum dim-levels and with the ‘1’ button the start-up brightness. The next time when the 230V power is switched on the lamp starts up at the adjusted dim-level.

Wireless Controlled Lightdimmer Using TV Remote Control: [Link]

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