Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: 5V relay

  1. #1
    Newbie
    Join Date
    Feb 2008
    Posts
    6

    5V relay

    Hi. My name is Dorian. I'm new to the forums. I read another post in this forum that dealt with 5v relays but my schematic and situation are a little different so I'm not sure how to apply that advice to my situation.

    MY PROJECT:
    I am using a homework board by Parallax. It has a built in microprocessor (BS2). The homework board is powered with a 9V battery.
    I want to connect the LEDs to a 5V relay, and then have the relay controlled by the processor.

    I have 4 LEDs connected in series. The LEDs are stuck into a cork and are then connected by sautered wires. The corks have been hot-glued to a 2'x2' piece of wood. Here is an example of how they are connected:



    Here is a diagram of how I have it connected at the moment:


    Here is the layout of my relay:


    I have tried different ways of hooking this up....nothing is working.

    Dorian

  2. #2
    Maximum Bitrate JimmyFitz's Avatar
    Join Date
    Nov 2005
    Location
    Austin, Texas
    Posts
    735
    You have too many LED's in series. Each one needs somewhere around 1.8 to 2.1 Volts when they conduct and light up, depending on the LED. Try just using one or two.
    ~Jimmy

  3. #3
    Newbie
    Join Date
    Feb 2008
    Posts
    6

    5v relay

    Thank you for the super quick response

    You were right. I used 3 LEDs and they were dim. I reduced to two LEDs and they got slightly brighter. I reduced to one LED and it was bright.

    Problem is...my project has a total of 18 LEDs and I need a way to power them.
    What do I need to power all 18....the microprocessor has to controll the lights.

  4. #4
    What can I say? I like serial. Curiosity's Avatar
    Join Date
    Mar 2004
    Location
    Florence Yall, BFKY
    Posts
    2,684
    Currently, your relay is doing nothing. Connect pin 0 of the homework board to pin 12 of the relay. pin1 of the relay should connect to ground. There should be a clamping diode between the pins so you don't fry the controller. pin 5 to nothing. pin 6 to some power source (+5V or +9V). Depending on the source voltage, you can connect a number of LEDs in series (V/2.1 or so) and that same number in parallel up to however many you need.

  5. #5
    Maximum Bitrate JimmyFitz's Avatar
    Join Date
    Nov 2005
    Location
    Austin, Texas
    Posts
    735
    Put two LED's in series with your resistor and then measure the voltage drop across the resistor. Use ohms law to recalculate the resistor you need to get the desired forward current through the LED's (check their rated max and use something less.) That will make those two brighter. Then connect more sets of two LED's in series with one resistor to the same 5V. So the result is that you would have nine of these strings in parallel. Each string is one resistor and two LED's. Make sure that your 5V source can give enough current for all nine strings. The strings add together in parallel.
    ~Jimmy

  6. #6
    Newbie
    Join Date
    Feb 2008
    Posts
    6

    5v

    YAY!!!!! I got 4 of them to light very brightly by doing it this way. I am about to hook up more and check them but I wanted to give a quick update.

    Dorian

  7. #7
    Newbie
    Join Date
    Feb 2008
    Posts
    6

    5V relay

    AWESOME!!!!

    It worked!!!!!! I got all 18 LEDs to light brightly. I changed the pins as you suggested and hooked the LEDs in parallel.

    Thank you again...your solution was brilliant

    Dorian

  8. #8
    Newbie
    Join Date
    Feb 2008
    Posts
    6

    5v relay to microprocessor

    Hi

    I have another question.

    I hooked up the circuit the way that was previously discussed. The LEDs light and they are very bright. However, the microprocessor is not controlling the LEDs and I need for it to. I suppose what I am asking is where do I connect the regular breadboard and LEDs to the relay or the microprocessor?

    Here is a picture of the circuit as it is currently:


    Here is a picture of the ferriswheel with the LEDs:



    Dorian

  9. #9
    Maximum Bitrate JimmyFitz's Avatar
    Join Date
    Nov 2005
    Location
    Austin, Texas
    Posts
    735

    Google is your friend

    Quote Originally Posted by dyampir View Post
    Hi

    I have another question.

    I hooked up the circuit the way that was previously discussed. The LEDs light and they are very bright. However, the microprocessor is not controlling the LEDs and I need for it to. I suppose what I am asking is where do I connect the regular breadboard and LEDs to the relay or the microprocessor?...
    Dorian
    You can put leds in series but you need current limiting resistors for the safety and longivity of your leds. Here is a link that shows how to drive from an output using a transistor.
    http://www.ee.ttu.edu/lab/robot/leds.htm
    ~Jimmy

  10. #10
    What can I say? I like serial. Curiosity's Avatar
    Join Date
    Mar 2004
    Location
    Florence Yall, BFKY
    Posts
    2,684
    disco strobe time. woo woo!

    There are lots of calculators online to figure out the resistor
    http://www.google.com/search?q=led+series+calculator

Page 1 of 2 12 LastLast

Similar Threads

  1. 5v relay wiring help!
    By aalouie in forum General Hardware Discussion
    Replies: 35
    Last Post: 04-01-2008, 01:05 PM
  2. StreetDeck Functions
    By god_of_cpu in forum DigitalMods (Scripts / API)
    Replies: 22
    Last Post: 01-15-2008, 10:44 PM
  3. AMP 1.X Phidget Plugin Interface
    By bcohen5055 in forum AMP
    Replies: 68
    Last Post: 09-06-2007, 12:10 AM
  4. Delay 5V
    By masch in forum Hardware Development
    Replies: 7
    Last Post: 04-12-2006, 01:15 PM
  5. Will someone help me program my relay control module
    By cproaudio in forum Software & Software Development
    Replies: 6
    Last Post: 09-04-2002, 04:50 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •