LED Police lights on a R/C truck

Discussion in 'The Projects Forum' started by jrwctj852zaf2, Nov 28, 2008.

  1. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    I'm trying to build a LED Police Strobe Lights circuit that will go on my Radio Control 1/10 scale truck. I would like to have 2 white for the front, 2 red for the rear, 8 or more Blue on top, and 1 yellow for each corner panel; a total of 16 or more LED's blinking. I would like them to blink 2 times (fast) and then a pause and keeps repeating. They will need to run off a 6vDC battery.

    please help?
     
  2. Wendy

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    Mar 24, 2008
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    Here is something I sketched up. If you're interested I'll come up with some values, but we'll need more information for the LED resistors.

    [​IMG]

    Blue and white LEDs use a bit more voltage, so they can't be paired up.
     
  3. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    I have 5mm White, Blue, Yellow, and Red LED's. The LED's Blue use 3.2v 11,000mcd, the Yellow use 2v 10,300mcd, the Red use 1.9v 18,150mcd, and the white use 3.2v 28,200mcd. If these LED's do not work well, should I get different ones. Is it possible to add more blue led's.
     
  4. Wendy

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    Mar 24, 2008
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    You can add as many blue LEDs as you want, within reason. The Vf was the numbers I was looking for. Due to the numbers this sucker could pull some heavy current, but the use is so intermittent that the batterys should last a little while. This means you'll need a largish capacitor I didn't show.

    One last question, do you want 20ma per LED? What is the current requirements you want?

    I figure ¼ seconds per blink (and ¼ seconds off) on the two blinks, followed by a second or so of off time. Sound about right?

    If you don't like the 555 appearance there are other ways. From the transistor back it would still remain the same.

    I could reduce the current a little by joining colors in pairs (say one blue and one red in a chain), but this would create a major wiring nightmare, so I'll keep it as is. If you want to go through the numbers I can show them, but I figure it is about 60 ma (assuming 20ma per chain).

    Even a little more voltage, say 7.5, would lower the current requirements quite a bit. 12 Volts would be better. Having one LED per chain is pretty wasteful.

    The numbers for the colors you gave are pretty typical, no getting around it.

    One last thing, take a look at how I grouped the LEDs. It would simplify your wiring harness a lot if you put the LEDs that are physically close to each other next to each other on the diagram. I'll need your input though. Say the white and the yellow, or the red and the yellow.
     
    Last edited: Nov 28, 2008
  5. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    Looks Good,
    The blinking timing sounds good (When I test it on a board can I change any thing for the timing?).
    Yes, I would like to have 15 to 20mA per LED, and only have a 6vDC 2,000mAh rechargeable battery on the R/C truck; which runs only 3 servo's right now.
    Yes I would like to group; if possible due to the 6v that I have; the LED's per corner (1 white and 1 Yellow for the front corners) and (1 red and 1 yellow for the rear corners). The Blue's will be on top arranged like a light bar.
    Will these all flash at the same time or do they alternate? For example will 1 white flash and the other white will be off; and then alternate.
    Can you please show me the numbers and what is each part that I will need to order?
    Thank You
     
  6. Wendy

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    Mar 24, 2008
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    Lets finish the design first. If you want alternating patterns this would be the time to ask, it would require additional circuitry (but not much). We might even change from 555's to something a bit more digital (it would still be easy though). If you hang around this site you'll find I don't mind designing and drawing, though I don't build as much as I should.

    I tend to focus on easy to get parts. If we go digital Radio Shack gets left behind. What part of the world are you in, and are their parts houses local?

    I could even just add two more 555s for the alternating pattern. We'll get a bit more information first. My personal system is KISS (Keep It Simple Stupid).

    You might think of adding 6 Volts more of batteries (rechargable or not, say 4 "AA"s), it really will make a difference in how long they last, and dramatically reduce the loading on the internal battery (which will still be used). You'll see the difference in the schematic, and it will simplify the wiring harness a lot.
     
  7. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    I live in USA Montpelier, Vermont.
    Radio Shack is just down the road, I can order from Digikey.com and/or mouser.com; makes no difference to me.
    Since the lights will be on seperate on/off switch, I will add more batteries to power just the lights; which will still be 6v.
    I would like them to alternate.
    Lets keep to the 20mA per LED.
    Lets not worry about the wire harness and there will be only 16 LED's on the truck.
     
  8. Wendy

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    Mar 24, 2008
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    You don't unterstand, with 16 LEDs there will be a wireing harness. Look at the schematic and mentally trace how the LEDs are going to light up, there will be bundle of wires involved... :D

    Part of the reason I keep wanting to up the battery voltage is to reduce it's thickness, dramatically (to about 1/3 the number of wires). But if you want a 6V power supply so be it.

    I'll be sketching for a while, so it'll probably be tomorrow before I get back with you. I'm thinking of using a simple digital chip.
     
  9. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    Yes I know there will be many wires, and many work hours to make, which is no problem for me.
    I will add another 6vdc 2000mAh battery pack for just the lights; which I have.
    Talk to you later.
     
  10. Wendy

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    Mar 24, 2008
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    I'm thinking of using a CD4017. It is a nifty little chip, it takes a clock signal (in this case ¼ sec) and sequences 1 of 10 outputs. You just connect to the pins you want to light up the LEDs through the transistor and you're in business. Best of all, it is made by lots of people.
     
  11. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    OK contact me when you have diagram.
     
  12. Wendy

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    Mar 24, 2008
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    I've left the design open ended, you can change the sequence in the table by moving, adding, or removing diodes. The diodes are critical to the design, they allow more than one output of U2 to be used for a single transistor. No diodes and the magic smoke escapes. The exact type of diode is extremely non critical.

    R1 will also allow you to select the speed of the movement. Again, I left it open ended. I have an experiment that used the same design you can check out.

    If you change the sequence please allow me to update the schematic, it will be going into my personal cookbook. Thanks.

    [​IMG]

    Parts List
    D1,5 – White LED
    D2,4,6,8 – Yellow LED
    D3,7 – Red LED
    D9-16 – Blue LED
    CR1-15 – 1N4454 (any diode will do)
    U1 – LM555
    U2 – CD4017
    C1 – 100µF
    R1 – 10KΩ Variable
    R2-7 – 2.7KΩ ¼W
    R8,10 – 39Ω ¼W
    R9,11 – 100Ω ¼W
    R12-17 – 150Ω ¼W
     
    Last edited: Jan 18, 2009
  13. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    Nice I think I understand but before changing anything else.

    Could you please explain the sequence.

    Do the LED flash twice quickly per Output on the U2 and then pause? or Do they flash once per Output then continue to the next output?

    Thank You
    Joe
     
  14. Wendy

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    Mar 24, 2008
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    Look at the sequence chart I put under the U1 and U2 schematics. U2 sequences in succession 0 to 9, and repeats. While the output (the column) of U2 is on any LED connected through the diode is lit. Each row (say D1) shows the sequence of each LED, each column shows which LED is on for each step. D1-4 blinks twice, then waits for the sequence to repeat. D5-8 alternates. D9-16 goes back and forth in pairs, then blinks.

    All of this is programable depending on where the diodes are put. You can select any pattern you like, just remember it takes place in 10 steps. There is a point of time, step 8, where nothing is lit.

    To restate it differently, as you look across the row of D1, each dot is ¼ of a second, with the entire row being 2½ seconds.
     
    Last edited: Nov 30, 2008
  15. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    Thank You for explaining the sequence.

    On the first sketch that you made what would be the values (Vcc @ 6vDC) and parts list Please? I'm thinking of useing this for a furture project!

    Thank You Again
    JOE
     
  16. Wendy

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    Mar 24, 2008
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    Do you still want the same times? ¼ Seconds flash rate, 1 second off?

    Still thinking of building the second sequencer? I was wondering if I scared you off.

    BTW, scroll down to the bottom of this vendors page, they have some interesting LEDs you might be interested in. If you put a flashing LED in series with other (not possible at low voltages like 6V) the flasher runs the rest.

    http://www.bgmicro.com/
     
  17. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    Yes I still want the times 1/4 sec. on twice and then 1 sec. off.

    I'm going to build both circuits, I'm very curious of how it will look.

    I have a police siren circuit too that I will build and a Knight Rider LED chaser circuit.

    So now I have serveral projects too work on for the winter months; along with building a R/C boat with LED navigation/head lights.

    JOE
     
  18. Wendy

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    Mar 24, 2008
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    OK, going through the excersise...

    [​IMG]
    Parts List
    U1,2 - LM555
    Q1 - 2N2222
    D1-5,8-10 - Blue LEDs
    D6,7 - White LEDs
    D11-14 - Yellow LEDs
    D15,16 - Red LEDs
    C1,2 - 100µF
    R1 - 10KΩ
    R2,3 - 3.3KΩ
    R4 - 180Ω
    R5-14 - 150Ω
    R15,16 - 100Ω
    R17 - 120Ω


    [​IMG]
     
    Last edited: Dec 2, 2008
  19. Wendy

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    Mar 24, 2008
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    The second sequencer will do a nice knight rider (aka cylon) light chase by moving the diodes around. There is another thread kicking around where they did this.
     
  20. jrwctj852zaf2

    Thread Starter Member

    Nov 28, 2008
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    Thank You for all your help!!

    JOE
     
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