Help required from a total novice !

Discussion in 'The Projects Forum' started by GroverT4, Oct 10, 2016.

  1. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    Dear all, but if a bizarre request this, but I'll give it a go! Firstly, I know absolutely nothing about electronics, and for that i apologise in advance.
    I have just acquired a VW T4 Campervan, and I want to try and create a bit of a quirky gadget to fit into the dash. I'll describe what I'm after, and if any of you good people what to try and help me make it happen, I'll be eternally grateful.
    Ok, I'd like a 'tally counter' ideally with a blue LED display. It would ideally have a memory, so that I could switch it off , and it would not reset the counter. It would need a power switch, and a button to manually advance the counter. It would ideally be wired into the vans electrics. The whole thing will,(if I ever get it off the ground) be mounted into the dash, probably to replace the ash tray, so it's not a massive bit of kit I am looking for. I went into Maplins and they suggested I try an online forum to see if anyone can help with the parts I would need, and some very very detailed idiot proof instructions on how to make it !
    Fingers crossed !!!
    Cheers
    JK
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,437
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    Welcome to All About Circuits!

    This is not that of a difficult project and in fact an ideal one for someone wanting to learn a bit about digital electronics.

    How handy are you? Are you good with a soldering iron? What type/brand of soldering iron do you already have?

    You will need to build a box and do some cutting and assemblying. Are you okay with that?
    How many digits on the display do you want? What are you tallying?
    Can you draw a little picture of the front of your counter you imagine, showing the display and locations of your switch and button. Show dimensions of the box too.
    Can you post a photo of where the ashtray is that you want to replace?
    Does your VW camper have a 12V auxiliary/cigarette lighter outlet?

    How close are you to Maplins? Where is the nearest Maplins or similar electronics supplier?
     
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  3. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    MrChips,
    Many thanks for your kind response. Alas I'm ashamed to admit I am not 'handy' at all. I've never held a soldering iron, and I have zero knowledge when it comes to electronics :(.
    The tally is a little something for the kids, they are amazed at the fact that other T4 drivers flash their lights and wave as you pass them on the road, and i suggested we should get a 'waveometer' , originally I planned on 2 displays one to record those that waved back , and one for those that didn't with a couple of suitable emoji type decals next to the relevant buttons.
    I'm not sure how big or small the workings will be, so it may be that I stick to just one display. I will try and take a picture and upload it after work today, i would estimate that the piece of dash trim i will use would be approx 6" square, including a recess where the ash tray was once situated. There is a 12v socket adjacent to it, which I currently use for the sat nav etc.
    There is a further 3 port 12v socket below about 2 feet away.
    Again I will try and draw a quick sketch of what I had in mind when I get home and try and post it on here. (I am prone to techno faffs however !)
    My nearest Maplins is about a ten minute drive away. The guys there were really helpful, they showed me some displays that were online, but they don't stock them themselves. They said if I sourced one they might be able to help with the components.
    As for the numbers I imagine 4 digits would be more than enough (I can't see us getting more than 9999 waves !)
    Like I said it's a bit of an odd project, but I'd love to pull it off.
    Hopefully with the help of kind people such as yourself !

    Thanks again

    JK
     
  4. Marley

    Member

    Apr 4, 2016
    142
    40
    As you know nothing about electronics, you could probably save yourself a lot of work (and money) by buying something like this on ebay:
    Counter 0.56inch LED display

    You will still need to connect a button of some sort and nicely mount it in your dash. You will be able to power it from the 12V outlet.
     
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  5. MrChips

    Moderator

    Oct 2, 2009
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    You will need some basic tools such as a soldering iron, wire cutting and stripping tools.
    Don't rush out a buy anything yet until you really need it.

    What year is the VW T4?
    Does your dash look something like this?

    upload_2016-10-10_8-46-38.jpeg

    Is there a USB socket nearby?
    upload_2016-10-10_8-48-16.jpeg

    Where do the kids sit? Just curious.

    It's funny what motorists do on the road. Bikers do it too.
    It happened when the first cute novelty autos hit the roads, Morris Minors, VW Beetle, Mini Coopers, Austin Mini, MGB, Triumphs etc. You don't see it as much these days. The novelty has worn off.
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,437
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    Good idea. It depends on what JK wants to accomplish, i.e. learn something about electronics versus just get the job done.

    If the former, this could be an AAC collaborative project. Someone like @nerdegutta or @Robin Mitchell can do the PCB while @takao21203 can source the components.
     
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  7. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    It's a 1998 T4
    I've taken a photo on my phone, so once I've worked out how to embed that into a reply , I can show you. It's not quite like that , the ashtray is where the drinks holder is in your picture. The 3 port 12v unit also has a USB port and it will be approx 2 feet away, housed in a 'centre console' which i have just bought from Audiosport and needs fitting.
     
  8. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    I like the sound of collaboration !! It's less daunting ! .. and when the van hits the pages of the T4 magazines I'll be sure to proffer the relevant acknowledgement !!
     
  9. hp1729

    Well-Known Member

    Nov 23, 2015
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    How big is the opening where you want to put the display?
    If you were supplied a schematic could you build it or do you need it ready to install?
     
  10. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    Hi,
    Thanks for the reply. I'm going to try and post a few pictures when I get home. Hopefully that will clarify what I am after, and my knowledge of all things electrical being zero .. the closer to ready to install the better ! Ha !
     
  11. MrChips

    Moderator

    Oct 2, 2009
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  12. hp1729

    Well-Known Member

    Nov 23, 2015
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    Design considerations:

    Do you want Zero Blanking". So a count of 12 comes out "12" in stead of "0012". Blank leading zeros.

    "Reset" button. On the front panel?, hidden inside? Not at all?

    Brightness control? Manual control. switch or pot? Automatic? None at all? If full brightness it appears to bright at night. If set for night it is too dim for day time.

    Displays come with a decimal point. You won't need them but they can be used to indicate low battery power or something.

    What size and kind of battery? Or use the car battery?

    Type of display? LED, LCD, ???

    "Lamp Test" feature?
     
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  13. MrChips

    Moderator

    Oct 2, 2009
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    Some very thoughtful considerations.

    Any dash mounted LED display should have auto-dim features. That is, the LEDs should be dimmed when darkness sets in otherwise they would be blindingly bright at night.

    This feature can be implemented with a light dependent resistor (LDR) and a pass transistor feeding the LED supply current.
     
  14. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    0

    Hi, thanks for the reply.
    Zero Blanking sounds like a good option.
    I was hoping it could be wired into the car battery with an on/off switch. I think a manual brightness control would be good. In the ideal world I was hoping to go with blue LED to match the vans colour scheme.

    I'm overwhelmed by the response on here, so nice to see that people are willing to help. I really am pretty ham fisted, and have a woeful track record when it comes to DIY, so I will certainly need plenty of help. It might be something that i might have to outsource if its too complicated for me. IMG_0482.JPG IMG_0851.JPG IMG_0852.JPG IMG_0849.JPG

    I hopefully have been able to attach a few pics.
    Firstly the van ! Named 'Grover' after the Sesame Street muppet. Theres the centre console, with the 3 socket /usb 12v power bar which will be fitted into it. Theres a picture of the ash tray and the set up there, and finally, I've measured up and tried to sketch what I had in my head. The 2 displays, and the buttons to advance the counters are positioned over what would be a void once the ash tray is removed. the idea would be to have a piece of dash trim (I have offcuts) mount everything to that, with (if its possible) all the workings fitting into that void, and fitting the plastic flush to the dash. if its not clear, its 135mmx 80mm.

    I hope this clarifies things, and that people are still able to help!

    thanks in anticipation !
    JK
     
  15. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    it was a big ask for me to get that right first time !
    here's the sketch. FullSizeRender.jpg
     
  16. nerdegutta

    Moderator

    Dec 15, 2009
    2,515
    785
    Hi, cool project.

    I'm in!
     
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  17. GroverT4

    Thread Starter New Member

    Oct 10, 2016
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    well all help greatly appreciated, i literally am clueless ! o_O
     
  18. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    I have some PCBs remaining for LED displays

    A small kind with 12 pins max = 4 digits can drive 20mA kinds directly.
    A larger PCB with 2x 24 IO and dual 16F59 possible.

    Id rather recommend just a low and high intensity switch. It will be easier.
    https://www.instagram.com/p/BLjTGHtBnR1/?taken-by=moonapteacup100

    Ive built one just a few days ago its literallly just a tiny TSSOP IC and one 22uH coil + display.
    It is possible to cram in a counter firmware so you dont need a master PCB using this as serial display.

    For pushbuttons add a resistor to vcc then ground them and test the pins for a small time slice.

    If you have the C language skills get a PICKIT3 + one PIC IC like the 16F54 or 16F57, solder a 5 pin header pretty much nothing else is needed.

    If not get a ready made module.

    Using TTL ICs is an option but its a lot of work to wire up a 7seg display since the 74XX dont use multiplexing.

    Arduino of course too I think the Atmel ICs source too much current to connect displays directly.

    There are 2 kinds serial displays on ebay, one with TM1637 the other with 74HC595 2x, so its pretty easy to send the serial bits while the TM1637 need a protocol, on the Arduino for sure theres a library.
    Very little needs to be changed to use the code for a PIC, besides, not possible for beginner.

    But these are just serial displays you couldnt cram in a counter firmware as well. So you need a host controller like Arduino.

    If you want permanent memory it gets a little complicated two options are battery backup and power down the controller, or write into EEPROM. So the 16f54 has not enough FLASH but the 16f59 could accomodate I2C.

    When you use a buck converter from 12v downto 5, it will work for almost 2 seconds with a small display after powering off and you can monitor digitally just with a Z diode and detect loss of external power dont need A/D converter measure the voltage.

    You could get all ready made modules to convert to 5v, serial displays and Arduino, or build some yourself.

    The Amazon product retains the counter when powering off + can work from 12v already.
     
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