New to electronics and need any assistance on a design project please...

Discussion in 'The Projects Forum' started by carpsicum2007, Nov 10, 2008.

  1. carpsicum2007

    Thread Starter New Member

    Nov 10, 2008
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    Hi everyone

    I am looking for any assistance and advice anyone may want to pass on. I'm doing a project and will explain what I want to achieve below, but I am totally new electronics so dont even know where to start. Ideally I would like someone to be able to offer a solution with drawings, components and the knowledge to help me to understand what I need to do.

    After some basic electronics reading I see this is a huge and complex field and just dont have the time to delve into this interesting but equally scary subject.

    The project.

    I would like to mount a series of LED's inline along 8 seperate paths. Each path is different in length. Each LED will sit approximately 15mm apart from center to center and therefore each path will have more or less LED's along each path.

    Each of these 8 paths start from the same point and I want them to start at the same time but take individual times to complete their path which I set to between 8 minutes and 45 minutes.

    Each path must stay lit until the longest and last path has completed then the complete circuit is repeated continously.

    I would like to use 3mm LED's and a 9V battery.

    All of this is mounted on a piece of 6mm acrylic measuring 1200mm x 700mm.

    The LED's and electronics need to be mounted on the backside of the acrylic.

    On the front of the acrylic I have slotted the paths and the course of the river Thames in London. The paths represent my usual cycle routes over a seven day period which I repeat weekly. As it is a contemporary and minimal map the river Thames scribed on the acrylic hints at the map of London.

    I will submit some jpegs in cad view so that everyone can physically see what I am doing.

    Many thanks to everyone viewing this..
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Do the LED's all light up at the same time as the path progresses, or must each path have it's own rate?
     
  3. carpsicum2007

    Thread Starter New Member

    Nov 10, 2008
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    Hi thanks

    I think that as long as the shortest path was equal to 8 minutes to complete versus the longest at 45 minutes then the rest can be stepped equally and incrimentally depending on their length....
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    What are the numbers of LED's in each path?

    And does each LED stay on once lit, or does only one along each pathway stay lit as the advance progresses?
     
    Last edited: Nov 10, 2008
  5. carpsicum2007

    Thread Starter New Member

    Nov 10, 2008
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    As I have to drill the holes manually after the CNC router process I have not got exact numbers as yet, I shall be doing that by wednesday.

    My guess is that the shortest will take roughly 60 - 80 LED's and the longest will take about 150 - 180 LED's.

    These are very rough figures for now though.

    As for the LED's.....each one will stay on once lit.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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    To be very Anerican - Zowie! That may be on the order of 800 LED's. At least I won't be the one making connections.

    At 10 milliamp/LED, that is going to take on the order of 8 amps of current. What color LED's were you planning to use (oddly enough, this is quite significant, as the color tells about how much voltage it takes to place each LED into conduction). That will influence the DC power supply to be used.

    This could be very wiring intensive. Hopefully, some others will come in with ideas, and we can get you to a satisfactory project. I see many shift registers....

    We recommend using microprocessors for many of these lighting projects, but I am not at all sure that would be the best course here. Time to hit the drawing board...
     
  7. carpsicum2007

    Thread Starter New Member

    Nov 10, 2008
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    Thanks for the input "beenthere".

    I think realistically I may increase the distance between the LED's to cut down on cost and connections as LED's are not exactly cheap, around 30 pence each.

    I was hoping to use clear LED's as my acrylic is a translucent but opaque green hue'd colour. I think clear would be the best colour to use aestethically.

    But any suggestions will be taken on board....

    I am very open to power supply but would prefer a battery source so that the piece may be mounted on the wall without any unsightly cables coming from the piece.

    Many thanks
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    I can guarantee you that a "transistor" type 9v battery will be woefully inadequate for this project.

    It is also a fairly complex project, particularly for an electronics "newbie".

    I strongly suggest that you start off by assembling a small pre-made kit, just to get your "feet wet". Here is a good one that's right in line with what you're trying to do:
    http://www.velleman.be/ot/en/product/view/?id=338563

    It consists of the basic "building blocks" of your eventual circuit, with an extra twist or two thrown in. Since the PCB is furnished along with all of the components and complete assembly instructions, your probability of success is far higher than attempting to start with a much larger scale project where minimal instructions would be provided.

    Your frustration level will be far lower.

    Velleman kits are available from a number of distrubutors worldwide. Their UK distributor list is here:
    http://www.velleman.be/dealer/search/?step=3&cid=57&did=4

    Maplin normally sells it for £6.99GBP, but they're out of stock at the moment.
     
    Last edited: Nov 10, 2008
  9. carpsicum2007

    Thread Starter New Member

    Nov 10, 2008
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    Thanks for the input SgtWookie.....it is a great idea to tackle a few of the pre made kits to milk my teeth and they are fun. As this is a final year major brief I would like to do a good job of my project.

    Any other input would be greatly appreciated in the construction of the electronics required.

    Many thanks
     
  10. beenthere

    Retired Moderator

    Apr 20, 2004
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    If you're good with the machine tools, perhaps a small behind-the-etched-scene traveller carrying an LED at an approximation of actual progress? Again, nothing that's going to run on a small battery, but less of a power hog than all those LED's.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    I looked at a couple of other distributor's sites for the MK107; ESR carries it for £4.75, considerably less than Maplin.
    Link: http://www.esr.co.uk/velleman/products/index_minikit.htm
    Direct link: http://www.esr.co.uk/velleman/mk107.htm

    Rapid claims to carry it for £4.25, but they're currently out of stock:
    http://www.rapidonline.com/searchresults.aspx?style=0&kw=MK107

    Basically, the kit consists of a 555 timer, a 4015 dual 4-bit static shift register, eight LEDs, a couple of push buttons; one allows you to randomly program LEDs to turn on, which get sequenced across and recycled to the 1st LED, the other pushbutton turns them all off. A potentiometer changes the speed of the LED display. There are other components that limit current through the LEDs (resistors) and another resistor and capacitor to set the rate for the 555.

    Really, I think it's the perfect introductory kit for what you're considering doing.

    And if you're willing to only light a single LED on each trail at a time, you might actually get through more than one cycle using a "transistor" 9v battery. Otherwise, you're going to need either a much more capable battery, or a mains-powered supply.

    [eta]
    You can view the assembly manual by clicking here:
    http://www.vellemanprojects.com/downloads/0/manual_mk107.pdf
    which also conveniently includes the schematic of the circuit.
     
    Last edited: Nov 10, 2008
  12. carpsicum2007

    Thread Starter New Member

    Nov 10, 2008
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    The only problem with that is 8 of them are needed and they would require a return path. All of this is to be mounted on the wall as well. Perhaps I need to bow to the idea that it needs to be plugged in to the wall, what are the implications of that?
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Do you mean, 8 of these kits?

    That's not really what I was thinking. What you WOULD need is a single 555 timer, and then a bunch of the 4015 dual 4-bit shift registers; one 4015 IC per every 8 LEDs on your longest route.

    Depends upon the number of LEDs you want to have illuminated at the same time, their Vf (forward voltage) vs the current, and what the supply voltage is.

    If you're using a 555 timer and 4015 shift registers, the maximum practical limit for the power supply is about 15v. Higher than that, and you risk zapping things.

    The wiring is going to get pretty complicated and tiresome.
     
  14. carpsicum2007

    Thread Starter New Member

    Nov 10, 2008
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    Sorry SgtWookie I was responding to beenthere's idea of creating a buggy of sorts to run along the path...which is where 8 of them come in. Tried to get a few of those MK107's today but alas no one in the UK has stock of them, I've exhausted the places to get them, including the places you suggested. Have made an enquiry to a Dutch firm and will hopefully get a response tomorrow.

    I have decided to reduce the LED's to 1 per inch now as the numbers seem to be creating too many issues power supply wise.

    But until I have had the acrylic cut I will not be able to quantify this. Till then I will work on understanding the process by making a few MK107's.
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    Well, you could always try acquiring the individual components for the MK107 kit and breadboarding it yourself. Not as easy as having the kit, but will be valuable experience.

    If you're interested in learning about electronics in general, you should consider picking up Radio Shack's Electronics Learning Lab. Cornwall Electronics carries it in the UK:
    http://www.cornwallelectronics.co.uk/product_info.php?products_id=43
    That's a bit more than they cost in the States, but I understand that taxes are quite high over there.
    It may be less expensive through t2retail.co.uk:
    http://www.t2retail.co.uk/Educational_Toys/Electronics_Learning_Lab
    Cornwall Electronics includes shipping in the £49.99 price.
    t2retail's £39.00 price does not; shipping starts at £8.00

    There isn't a 4015 IC in the lab, but you could always get a few and experiment with them.

    The only thing you need besides the lab itself is six "AA" batteries.
     
    Last edited: Nov 11, 2008
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