element14 Community
element14 Community
    Register Log In
  • Site
  • Search
  • Log In Register
  • About Us
  • 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 Boards Community
    • Dev Tools
    • Manufacturers
    • Multicomp Pro
    • Product Groups
    • Raspberry Pi
    • RoadTests & Reviews
  • 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
      •  Korea (Korean)
      •  Malaysia
      •  New Zealand
      •  Philippines
      •  Singapore
      •  Taiwan
      •  Thailand (Thai)
      • 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
555 Timers
  • Technologies
  • More
555 Timers
Forum 555 timer bistable
  • Blog
  • Forum
  • Documents
  • Polls
  • Files
  • Members
  • Mentions
  • Sub-Groups
  • Tags
  • More
  • Cancel
  • New
Join 555 Timers to participate - click to join for free!
Actions
  • Share
  • More
  • Cancel
Forum Thread Details
  • Replies 7 replies
  • Subscribers 48 subscribers
  • Views 1808 views
  • Users 0 members are here
Related

555 timer bistable

Psin545
Psin545 over 2 years ago

imageI have a question regarding some behaviour of a 555 timer circuit in bistable mode. I attached a photo I found off the internet that is the one I’m using, the output goes to a 440 ohm resistor and then to a red LED also I’m using 10k pull up resistors. I noticed when I push the trigger pin switch and the light comes on, that sometimes when my hand is hovering over the circuit the LED goes out. I got curious and made sure not to bang into anything or touch anything and I would slowly bring my hand near the circuit, and almost half or more of the time the LED would turn off. Being more curious now I took the breadboard set up like a “bridge” (basically I have two small bins and I had the breadboard laying across so each end of the breadboard is resting on those bins and there’s nothing touching the bottom of the breadboard) I noticed that if I put my hand under the breadboard (without touching it at all!) the LED light on the output pin goes out. Getting more curious I held the breadboard by the sides so there was minimal contact and the light would work perfectly fine until I ran my hand close to (but still not touching) the breadboard. I tried this on different surfaces such as plastic bins, slabs of wood, the floor (lol) and on a glass table. It did it the least amount of times when laying on the plastic bin. I’m not using a anti static wrist strap but I’m curious if this is an environment issue or like a workstation issue? Or a simple fix with a anti static strap? It was kind of neat to play around with it like that but now I wonder about the last 2 years and all the heart ache from circuits not working properly even though I was CERTAIN I had built them exactly as per the diagrams. Also I tried 5 different 555 chips and 5 different breadboards with the same results. Any ideas or suggestions? 

  • Sign in to reply
  • Cancel

Top Replies

  • shabaz
    shabaz over 2 years ago +6
    Hi, Not everything on the Internet is reliable. If you look at the datasheet of the chip , on page 10, you'll see the proper circuit. The clue (in case you're wondering how come I knew to check the…
  • dougw
    dougw over 2 years ago +6
    It looks like you have discovered a way to make a kind of proximity sensor. Maybe if you connect an otherwise unconnected wire to pin 6 it will be even more sensitive.
  • Psin545
    Psin545 over 2 years ago in reply to shabaz +2
    Thanks it’s funny cause after I posted this I went to lay down for a bit and as I was laying there I said to myself “you left pins floating” haha. I should of known better. I’ll check those links out though…
Parents
  • AE7HD
    AE7HD over 2 years ago

    Why is the title "Monostable"?

    • Cancel
    • Vote Up +1 Vote Down
    • Sign in to reply
    • Cancel
Reply
  • AE7HD
    AE7HD over 2 years ago

    Why is the title "Monostable"?

    • Cancel
    • Vote Up +1 Vote Down
    • Sign in to reply
    • Cancel
Children
  • Psin545
    Psin545 over 2 years ago in reply to AE7HD

    I meant to write bistable, my bad 

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
  • AE7HD
    AE7HD over 2 years ago in reply to Psin545

    Can you edit the title?

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
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