element14 Community
element14 Community
    Register Log In
  • Site
  • Search
  • Log In Register
  • Community Hub
    Community Hub
    • What's New on element14
    • Feedback and Support
    • Benefits of Membership
    • Personal Blogs
    • Members Area
    • Achievement Levels
  • Learn
    Learn
    • Ask an Expert
    • eBooks
    • element14 presents
    • Learning Center
    • Tech Spotlight
    • STEM Academy
    • Webinars, Training and Events
    • Learning Groups
  • Technologies
    Technologies
    • 3D Printing
    • FPGA
    • Industrial Automation
    • Internet of Things
    • Power & Energy
    • Sensors
    • Technology Groups
  • Challenges & Projects
    Challenges & Projects
    • Design Challenges
    • element14 presents Projects
    • Project14
    • Arduino Projects
    • Raspberry Pi Projects
    • Project Groups
  • Products
    Products
    • Arduino
    • Avnet & Tria Boards Community
    • Dev Tools
    • Manufacturers
    • Multicomp Pro
    • Product Groups
    • Raspberry Pi
    • RoadTests & Reviews
  • About Us
  • Store
    Store
    • Visit Your Store
    • Choose another store...
      • Europe
      •  Austria (German)
      •  Belgium (Dutch, French)
      •  Bulgaria (Bulgarian)
      •  Czech Republic (Czech)
      •  Denmark (Danish)
      •  Estonia (Estonian)
      •  Finland (Finnish)
      •  France (French)
      •  Germany (German)
      •  Hungary (Hungarian)
      •  Ireland
      •  Israel
      •  Italy (Italian)
      •  Latvia (Latvian)
      •  
      •  Lithuania (Lithuanian)
      •  Netherlands (Dutch)
      •  Norway (Norwegian)
      •  Poland (Polish)
      •  Portugal (Portuguese)
      •  Romania (Romanian)
      •  Russia (Russian)
      •  Slovakia (Slovak)
      •  Slovenia (Slovenian)
      •  Spain (Spanish)
      •  Sweden (Swedish)
      •  Switzerland(German, French)
      •  Turkey (Turkish)
      •  United Kingdom
      • Asia Pacific
      •  Australia
      •  China
      •  Hong Kong
      •  India
      • Japan
      •  Korea (Korean)
      •  Malaysia
      •  New Zealand
      •  Philippines
      •  Singapore
      •  Taiwan
      •  Thailand (Thai)
      • Vietnam
      • Americas
      •  Brazil (Portuguese)
      •  Canada
      •  Mexico (Spanish)
      •  United States
      Can't find the country/region you're looking for? Visit our export site or find a local distributor.
  • Translate
  • Profile
  • Settings
Arduino
  • Products
  • More
Arduino
Arduino Forum overheating resistors
  • Blog
  • Forum
  • Documents
  • Quiz
  • Events
  • Polls
  • Files
  • Members
  • Mentions
  • Sub-Groups
  • Tags
  • More
  • Cancel
  • New
Join Arduino to participate - click to join for free!
Actions
  • Share
  • More
  • Cancel
Forum Thread Details
  • Replies 35 replies
  • Subscribers 408 subscribers
  • Views 2797 views
  • Users 0 members are here
  • help
  • overheating
  • arduino
  • relay
Related

overheating resistors

dirtdiver
dirtdiver over 13 years ago

Hi, im using the arduino to turn on a relay and complete a curcuit connecting the USB to a curcuit like this one :

 

    The IR's are TSHA203  , 100mA , Vr -5V, 180mW,image

Now one thig i dont understand is how 5 * 0.1 = 0.5 W and not 0.18 W, so I assumed that it could work on lower values like 2 volts or 50 mA and these are the maximum ones.

...But i guess i was wrong couse the resistors are overheating.Can you guys point me in the right direction?

Thanks!

  • Sign in to reply
  • Cancel

Top Replies

  • Former Member
    Former Member over 13 years ago +1
    You need to ask yourself "Do I need to drive with 100ma or not?". 100ma is the maximum non pulsed current allowed. As you already know, then the resistors need to dissipate about 500 mW. If the answer…
  • billabott
    billabott over 13 years ago +1
    Having watched this YouTube Video in order to learn what a "freetrack helmet" is; I have a suggestion in the form of a question. Why not use a single LED and 3 bundles of optical fiber(s)? These LEDs:…
  • R_Phoenix
    R_Phoenix over 13 years ago in reply to dirtdiver +1
    interesting idea indeed, but if i use optical fiber first I would have to find optical fiber , http://www.mouser.com/Search/Refine.aspx?N=11203177
Parents
  • Nate1616
    Nate1616 over 13 years ago

    I agree with Phoenix in that you would need a half watt resistor.  2 volt drop across the IR is a good estimate since its usually between 1.6V to 2.2V.  hope this helps

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
Reply
  • Nate1616
    Nate1616 over 13 years ago

    I agree with Phoenix in that you would need a half watt resistor.  2 volt drop across the IR is a good estimate since its usually between 1.6V to 2.2V.  hope this helps

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
Children
No Data
element14 Community

element14 is the first online community specifically for engineers. Connect with your peers and get expert answers to your questions.

  • Members
  • Learn
  • Technologies
  • Challenges & Projects
  • Products
  • Store
  • About Us
  • Feedback & Support
  • FAQs
  • Terms of Use
  • Privacy Policy
  • Legal and Copyright Notices
  • Sitemap
  • Cookies

An Avnet Company © 2025 Premier Farnell Limited. All Rights Reserved.

Premier Farnell Ltd, registered in England and Wales (no 00876412), registered office: Farnell House, Forge Lane, Leeds LS12 2NE.

ICP 备案号 10220084.

Follow element14

  • X
  • Facebook
  • linkedin
  • YouTube