Greetings, Newbie help for led flasher circuit

Discussion in 'The Projects Forum' started by gsxrglen, Sep 16, 2012.

  1. gsxrglen

    Thread Starter New Member

    Sep 16, 2012
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    Hi all, I have got my first breadboard and I would like to build a circuit with 4 flashing (wig wag) style for my daughters 12v (toy) car. I searched the forums and can't find what I am looking for.

    Basically, I want 2 leds in the front flashing and 2 in the rear.

    Does anybody have an existing schematic I can use to build this or point me in a direction to find one?

    Basically my daughter is dressing up as poilce for haloween, so i told her I would do up her ride on car.


    Thanks for any help.

    Cheers.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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  3. gsxrglen

    Thread Starter New Member

    Sep 16, 2012
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    Thanks MrChips. That is sort is what I am looking for except with 12 volts instead of the nine volts on that circuit. I also am looking to flash 4 LEDs.

    Please keep in mind I am very new to this stuff. I understand what capacitors,diodes etc do but can't design a circuit yet......... Well one that works anyway. Lol :D
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    That circuit will work on 12V too.
    You can replace R3 and R4 with a single fixed resistor, once you find the right flash rate want.
     
  5. gsxrglen

    Thread Starter New Member

    Sep 16, 2012
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    Thank you sir. I will do some experimenting on the breadboard.

    One last question, what determines the flash rate on that circuit?
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    The combination of R3 + R4 and C1.
    Increasing the resistance and/or capacitance will give a longer period (i.e. slower rate).
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    I wrote that article, I also wrote this...

    LEDs, 555s, Flashers, and Light Chasers

    If asked nicely, I will design to order. :D I also really like kids, and have never outgrown my fascination with flashy circuits.

    Be careful with the new generation of LEDs, even at 20ma if put right next to the eyeball there is the chance they can do damage, they are not light bulbs. The older generations were very very dim. This has changed.
     
  8. gsxrglen

    Thread Starter New Member

    Sep 16, 2012
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    Hey Bill, I have the same feelings as you. Always been facinated by electronics and "flashy" lights.

    I must admit this project is partially for me because I would have liked a ride on with cool lights when I was young :D

    I did look at your write ups when searching, but being a newbie I also found it a little confusing.

    If you would design me a circuit it would be greatly appreciated ;)

    So basically I have a 12volt ride on car. and want to install 1 led bulb in each headlight and 1 in each tail light and make them flash alternately (wig wag)

    The led's i have are about 3.0v and 20ma forward current I think.

    If I was more confident, it would be really cool if I could control it with a three way switch. In one position the lights are on solid and flip the switch and they flash but that is probably a lot more complicated.

    Any help is greatly appreciated.
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    Is this going to be part of the car? We have a restriction about automotive modifications on this site, I have been known to go to ETO if it was something people needed.

    Read the TOS, then get back with me.
     
  10. DickCappels

    Moderator

    Aug 21, 2008
    2,651
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    Bill,

    I think this one requires a judgment call.

    Some text removed from the quote below and some text made bold for emphasis.

    So is this in violation of the TOS?
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    Nope, I had forgotten that part.
     
  12. ScottWang

    Moderator

    Aug 23, 2012
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    767
    If you could describe more clearly, maybe it's not so hard.

    Something like :
    Key → NE555 Monostable → CD4518 → Transistor drivers → LEDs
    Key → NE555 Monostable → CD4518 → ULN2003 → LEDs (if more LEDs used)
    Key → NE555 Monostable → CD4518 → Transistor drivers → Relay
    Key → NE555 Monostable → CD4518 → ULN2003 → Relay (if more Relay used)

    Or :
    Key → NE555 Monostable → CD4017 → Transistors driver → LEDs
    Key → NE555 Monostable → CD4017 → ULN2003 → LEDs (if more LEDs used)
    Key → NE555 Monostable → CD4017 → Transistors driver → Relay
    Key → NE555 Monostable → CD4017 → ULN2003 → Relay (if more Relay used)

    Or some other else.
     
  13. gsxrglen

    Thread Starter New Member

    Sep 16, 2012
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    This is the "car" in question.
    If it is a violation of the rules I will understand. I guess you don't need people making their real cars into police impersonators.

    [​IMG]
     
  14. gsxrglen

    Thread Starter New Member

    Sep 16, 2012
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    0

    I wish I could comprehend what all that is ^^ lol. :eek:

    Sorry for being such a newb but I dont get that.

    I have some 555 timers, capacitors etc at my disposal. I was thinking it would be kinda neat if I had a switch on the dash for her. Say in the up position both headlights (1 led each) and both tail lights (1 led each) are on solid - just like a regulare car headlighs. Then flip the switch down and the same leds start flashing in a wig wag pattern ie: LRLRLRLRL........

    I'm sorry, wish I could be more technical.
     
  15. ScottWang

    Moderator

    Aug 23, 2012
    4,854
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    I already designed a circuit for your need.

    1. Pin 1 of NE555 is designed to reduce the current comsumption, when NE555 not working, then just turn it off, if you don't want to do this, then you just cut the wire connection and connecting Pin 1 to GND.

    2. When the Sw1 at the position 3, then the OR gates will all set to Hi, and it will cause 4 Output pins of ULN2003 become Lo, and then the 4 LEDs will get the current and lighting.

    3. About the Pin 5 of ULN2003, I will treat it like as a inveter, this will make U2 to do the LED flashing for Left side and Right side.

    4. Calculating the resistors of LED1~LED4.
    a) assume Vce=0.9V of ULN2003 inverter.
    b) LED = 3V/20mA, considering about the LED brightness and Life, I just set it to about 80% of 20mA, that is 16mA.
    R = (12V - Vf(LED) - Vce(ULN2003)) / 16mA
    = (12V-3V-0.9V)/16mA
    = 8.1V/16mA
    = 506Ω, choose 500Ω.

    5. U2a,U2b ctrl the Left side of two LEDs. (CD4071)
    6. U2c,U2d ctrl the Right side of two LEDs. (CD4071)
    You can choose the pin of CD4071 by yourself. (Pin 14:12V,pin 7:GND)

    7. You should study it more, and post your question, if you know more about the theory of this circuit, then you can adjust everything you want.

    * I'm not try this circuit yet, so if you have any probolem, just post it.

    [​IMG]

    CD4071 OR Gate.
    http://www.datasheetcatalog.org/datasheets/105/109272_DS.pdf

    ULN2003 datasheet:
    http://www.datasheetcatalog.org/datasheet2/f/0c6x6a46ig46qlxf3j2qsaii8o3y.pdf
     
    Last edited: Sep 22, 2012
    gsxrglen likes this.
  16. gsxrglen

    Thread Starter New Member

    Sep 16, 2012
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    Thanks very much Scott! I will study this and grab a ULN2003 from the electronics store and give it a try.

    One question. What is component Ua,Ub,Uc, and Ud?

    I have not seen these before.

    I really appreciate you taking the time to design and do a schematic for me. :D
     
  17. ScottWang

    Moderator

    Aug 23, 2012
    4,854
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    If you look back carefully then you will find it, and I also shows the datasheet.
    5. U2a,U2b ctrl the Left side of two LEDs. (CD4071)
    6. U2c,U2d ctrl the Right side of two LEDs. (CD4071)

    I'm not sure how fast the flashing speed you want, so you may adjust R2 to change the speed.
     
    Last edited: Sep 23, 2012
  18. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    U2 is a quad 2-input OR gate (CD4071). That means it has 4 devices in one package. They are shown separately on the schematic with the letter suffixes a-d. The power and ground connections on pins 14 and 7 respectively are also sometimes not included in schematics. This is just one of the many reasons you should download and familiarize yourself with the datasheets for all ICs in your circuit.

    [​IMG]
     
    Last edited: Sep 23, 2012
  19. NFA Fabrication

    Member

    Aug 12, 2012
    104
    3
    I just did basically the exact same thing that the OP is trying to do, but in an RC truck. The truck runs on 3 cell lithium batteries that around 12.6V fully charged, so my solution may work for the OP too!

    I used the Arduino Uno micro controller, and wrote a basic code for the flashing lights. It pulses one side 3 times, and then pulses the other side 3 times on loop. It was very simple to wire up and I will give you the coding I used. The Arduino Uno can be had for about $15 on Ebay, or if you want one RIGHT NOW, radio shack has them for about $35. What I like about this is that once it is set up, it is simple to manipulate the numbers to get the flash just how you want it. I am new to all of this electronic stuff as well, but this was very simple to do.

    View My Video

    Here is the basic diagram (I used 1K resistors at the transistors, and 330's at the LED's, but that will be dependent on your LEDS):

    [​IMG]

    And simply past the following code into the Arduino:

    /*
    Blink
    Turns on an LED on for one second, then off for one second, repeatedly.

    This example code is in the public domain.
    */

    // Pin 13 has an LED connected on most Arduino boards.
    // give it a name:
    int led = 13;

    // the setup routine runs once when you press reset:
    void setup() {
    // initialize the digital pin as an output.
    pinMode(led, OUTPUT);
    }

    // the loop routine runs over and over again forever:
    void loop() {
    digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
    delay(50); // wait for a second
    digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
    delay(50); // wait for a second
    digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
    delay(50); // wait for a second
    digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
    delay(50);
    digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
    delay(50); // wait for a second
    digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
    delay(250);
    digitalWrite(12, HIGH); // turn the LED on (HIGH is the voltage level)
    delay(50); // wait for a second
    digitalWrite(12, LOW); // turn the LED off by making the voltage LOW
    delay(50); // wait for a second
    digitalWrite(12, HIGH); // turn the LED on (HIGH is the voltage level)
    delay(50); // wait for a second
    digitalWrite(12, LOW); // turn the LED off by making the voltage LOW
    delay(50);
    digitalWrite(12, HIGH); // turn the LED on (HIGH is the voltage level)
    delay(50); // wait for a second
    digitalWrite(12, LOW); // turn the LED off by making the voltage LOW
    delay(250);
    }
     
    Last edited: Sep 24, 2012
  20. ScottWang

    Moderator

    Aug 23, 2012
    4,854
    767
    I added the Pin Number of CD4071 on the circuit, you can exchange the gate you like.

    The OR gate(CD4071) function is when one of input pin is Hi, then the output will be Hi, the Hi in logic also called '1', and Lo called '0', the Hi or '1' represent the voltage at here is 12V.

    [​IMG]
     
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