Saturday, 12 January 2013

Light-sensitive Alarm Project


The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.
  • The light-sensitivity of the circuit can be adjusted by varying the 100k preset.
  • The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.
Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.
This project uses an edge-triggered 555 monostable circuit.

Parts Required

  • resistors: 10k, 47k, 1M ×3
  • presets: 100k, 1M
  • capacitors: 0.01µF, 0.1µF, 10µF 25V radial
  • transistor: BC108 (or equivalent)
  • 7555 low-power timer IC
  • 8-pin DIL socket for IC
  • LDR (light-dependant resistor) type ORP12
  • bleeper 9-12V
  • on/off switch
  • battery clip for 9V PP3
  • stripboard 12 rows × 25 holes

Stripboard Layout

Stripboard layout for light-sensitive alarm

Circuit diagram

Circuit diagram for light-sensitive alarm

Model Railway Level Crossing Lights


A magnet under the train operates reed switches positioned on the track. The trigger reed switch starts the sequence by switching on the amber light, a few seconds later the two red lights start to flash. When the train has passed the level crossing it operates the cancel reed switch which switches off the lights until the next train arrives.
There is a PCB pattern for this project, but if you don't have facilities to make PCBs you can build this project on stripboard instead. Please see the New Railway Modellers website for a stripboard layout and advice on making model lamps and barriers.
This project uses a 555 monostable circuit to switch on the amber LED for a few seconds. When this switches off it triggers a 555 bistable circuit which switches on a 555 astable circuit to flash the red LEDs.

Parts Required

Level crossing lights
  • resistors: 680 ×3, 1k ×3, 33k, 47k, 82k, 270k
  • capacitors: 0.1µF ×3, 10µF radial ×2
  • red LED (3mm best) ×2
  • amber* (or yellow) LED (3mm best)
    some amber LEDs are too orange to look correct, yellow may be better
  • 555 timer IC ×3
  • 8-pin DIL socket for IC ×3
  • on/off switch
  • battery clip
  • reed switch ×2
  • miniature magnet - each locomotive needs one
  • printed circuit board (PCB) - pattern given below

PCB component layout

PCB component layout for model railway level crossing lights

Track connections

Track connections for model railway level crossing lights
    The reed switches can be held in place between the rails with a small piece of blu tac.
    Each locomotive will need a miniature magnet glued to its underside, test first with blu tac, then use superglue.

Circuit diagram

Circuit diagram for model railway level crossing lights
Circuits: 555 monostable (on left) | 555 bistable (in middle) | 555 astable (on right)

PCB copper track pattern

PCB track pattern model railway level crossing lights

Stripboard layout

If you don't have facilities to make your own PCB you can build this project on stripboard. Please see the New Railway Modellers website for a stripboard layout as well as advice on making model lamps and barriers

Electronics Projects – Mini Projects and Final Year Projects

Following are mini project ideas for Electronics Engineering students:

    • Home Automation (Ac/Dc) Using Pc Interface
    • Color Reflectance Measurement (Solids)
    • Access Control System
    • Infrared Toy Car Motor Controller
    • Dc Motor Direction Control
    • Logic Analyzer
    • Line Telephone Share
    • Simple Code Lock
        • Leaf Moisture Analyzer
        • Industrial Automation Data Acquisition System
        • Variable Auxiliary Power Supply
        • Microcontroller based Scrolling Message Display
        • Ultra Bright LED Lamp
        • DTMF Development Board
        • Mobile Cell Phone Charger
        • Data Logger
        • Solar Battery Charger And Shunt Regulator
        • Automatic Light Lamp with Morning Alarm
        • G.P.S. Receiver
        • FM Booster
        • LED Panel Meter
        • Air Flow Sensor
        • 7 Digit Code Lock (6 – 15v)
        • Light Sensitive Inductive Load Controller
        • Robot Control Using TV Remote
        • FET 4 Input Mixer (+/-9v)
        • Quality FM Transmitter
        • Autonomous Robot
        • Classic Ac 230 V Timer
        • Infrared Control For Pc
        • Altimeter — To Measure The Altitude
        • Build A Simple Infrared Illuminator
        • Fire & Smoke Alarm System
        • House security system
        • Electronic security system
        • Clap Switch
        • Stepper Motor Control Using Microcontroller
        • 4 Digit 7-Segment Multiplex DISPLAY
        • Infrared Auto Switch
        • Digital Alarm Clock
        • Light Sensing Robot
        • Ionizer Mains (230v Ac)
        • Dc Motor Control PWM Technique
        • Telephone Number Display
        • DTMF Proximity Detector
        • U.S.B. Connectivity To Micro Controller
        • Automatic Control for Unmanned Railway Gate.
        • Telephone Receiver
        • Solar Lighting System
        • Build A Carbon Monoxide SNIFFER
        • Liquid Dispensing System with Touchscreen
        • Temperature Controlled Soldering Station
        • Microcontroller Based Intelligent Glass Break Detector
        • Telephone Call Counter
        • Electronic watchdog
        • Automated Traffic Signal Controller
        • Fastest Finger First Indicator
        • DTMF Telephone Remote Control
        • Line Follower Robot
        • Automated Car Parking System
        • Depth Of The Medium Based On Attenuated Reflectance
        • Dual Motor L298 H-Bridge Control
        • Micro Controller To Ethernet Interface
        • Baby Incubator
        • Interfacing IBM Key Board To Micro Controller
        • Intelligent Battery Charger
        • UNIPOLAR 4-Phase Stepper Motor Controller Board
        • Condenser Mice Audio Amplifier
        • Electronic Eye With Security System
        • Who’s First (Game) Indicator
        • Auto turn off battery charger
        • Micro Controller Clock
        • L293 H-Bridge Dc Motor Controller
        • Invisible Broken Wire Detector
        • Wireless Vehicle Path Tracer Using IR & RF
        • Electrical Equipment Controller
        • Simple Function Generator 12v
        • Musical Touch Bell
        • Electronic Jam
        • Anti Theft Alarm For Bikes
        • IR Remote Switch

Saturday, 18 June 2011

Cool Home-Built Robot Projects on the Web

Introduction
Greetings to all past, present, and future roboticists and tinkerers.  I know there are about a zillion web pages out there pointing to everything imaginable and sometimes unimaginable, but I thought I'd try adding something a little different to the hopper.  This article mostly points to sites with "home-built" robot information that shows that projects can be started and finished (at least to the point of having a machine that actually moves or does something).  The list below in not by any means exhaustive (although collecting and checking it all was exhausting!), but a modest collection of cool places where you can see what people are doing and in many cases, how they did it.    Building your own robot is a very challenging and rewarding experience, but it takes perseverence and patience to see it through to completion.  I hope you enjoy the voyages through these web pages.  The sites and the robots give you a little flavor of the people who made them and maybe some inspiration to "keep on keeping on".
The 50+ builders listed below are arranged alphabetically by last name.  Some will be familiar and some not, but all share a kinship of robotics as a hobby or buisiness.   I hope to provide links to interesting success stories that have been posted to the Web.  I want to help people find out about one-of-a-kind, home-built robots from people who have built them.  There are walkers, wheeled machines, arms, simulators, etc.  These sites show real robots and projects built by real people using real hardware and software.  My hope is that you can use this article as a convenient jumping point to practical technical information about some successful personal robotics projects.
I have tried to capture the gist of some of the websites by listing the robot names if available and/or some brief information about the website.  No pictures are included here since the websites will no doubt be updated and changed from time to time.
Explanation
The "Projects" link point as directly as practical to the actual robot information.  Most of these sites have both pictures and text.  The "Homepage" link points to the builder's home webpages where there is likely to be lots of other good, but not necessarily related information.   Homepages are referenced if no specific section for their robot projects was available.  Use this list to pop in on these websites from time to time and see what's happening.  Also, consider that many of these sites have "interesting" or "useful" links to still other places.  One could spend a lifetime following all the possible paths!
Let me know what you think of this type of article.  If you have other interesting ideas, feel free to pass them along to me.
Enjoy the journey!!

new technology

Hi friends.........your most welcome in new technology.Here i'll tell you about the projects