(Topic ID: 99567)

DIY: How to add a GI circuit switch to an LED backbox

By lyonsden

7 years ago


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  • Latest reply 3 years ago by Rensh
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    #1 7 years ago

    The motivation for this project came after I had finished replacing the florescent tube in my Tron with an LED backbox and a set of flashers connected to the playfield flashers. Tron has some very neat lighting effects, including shutting off the playfield GI at various points in the game such as when you drain a ball or the game ends. While the GI is off, the playfield lights and flashers put on a very nice show.

    After all the work in getting the flashers in the LED backbox, I thought it would look great if the LEDs in the backbox would also shutoff with the GI, so the flashers in the backbox would really pop (especially at night). I soon realized that to do this, I was going to need to learn some electronics and circuit design. After a long weekend of research on the web and lots of help from people who know more about this stuff than I do (big shout out to Copperpot!), I was able to put all the pieces together to make this work. The end effect is pure awesome.

    #3 7 years ago

    This is probably a bit more advanced that my other how-tos. Overall, it takes less time, but there is the soldering together of a few electrical components. However, I'd never done anything like this before. I'm pretty sure that as long as you can solder, and take your time making sure that everything is correctly connect and oriented, you should be able to do this without any problem. Still, it might be good to buy two of each component, just in case.

    If you want to the other tutorials (which I recommend doing before tackling this one):
    LED backbox: https://pinside.com/pinball/forum/topic/how-to-make-an-led-backbox-for-30-for-modern-sterns
    LED Flashers in backbox: https://pinside.com/pinball/forum/topic/how-to-make-flashers-or-under-cabinet-lighting-for-15-for-modern-sterns

    For this how-to, I am going to list all the parts you'll need (and where to get them), the tools you'll need, and a set of step-by-step instructions. Unfortunately, because I was doing a lot of testing while I figured this out (and undoing, redoing, and starting over), I do not have as complete a set of pictures as I've had in the other how-tos. Since I haven't done this on a second game yet (which is usually when I take photos) and I'm not sure when I'll get to that, I want to make sure that I get these written before I forget the details. As such, this won't be quite as detailed as the previous how-tos, but I hope it is enough to let people make this themselves (as well as help my memory in the future).

    #4 7 years ago

    Parts:

    Capacitor for signal smoothing (100uf, 50V): https://www.greatplainselectronics.com/proddetail.asp?prod=CER-100uF-50V-RLC

    Bridge rectifier (600V 2A): Part Number: 2KBP06M: https://www.greatplainselectronics.com/products.asp?cat=172

    Transistor: Part Number: TIP142T (100V, 10A) or Part Number: TIP122 (100V, 5A): https://www.greatplainselectronics.com/products.asp?cat=101
    Data sheet for TIP122: http://www.adafruit.com/datasheets/TIP120.pdf

    9-pin "0.156 header
    Great Plains sells a 24-pin header that you can cut ($1.35): https://www.greatplainselectronics.com/proddetail.asp?prod=26-48-1241

    9-pin "0.156 connector plug ($0.30):
    Part Number: CS156-09-LR at Great Plains: https://www.greatplainselectronics.com/products.asp?cat=81

    Crimp contacts x9 ($0.08):
    Part Number: 08-50-0134 at Great Plains: https://www.greatplainselectronics.com/products.asp?cat=80

    22 gauge wire
    heat shrink tubing
    electrical tape

    #5 7 years ago

    Tools:

    Wire cutters: cutting wire
    Wire strippers: stripping wire
    Soldering iron: soldering wire
    Solder: soldering wire
    Crimping tool/needle nose pliers: crimping contacts to wire
    Helping hands: holding connector and header while soldering
    Heat gun: shrinking heat shrink tubes
    Scissors: cutting electrical tape

    #6 7 years ago

    Directions: Stern SAM

    Making the harness:
    Step 1: Locate connector J15 on the I/O Board. This located in the upper-left corner.

    Step 2: Making sure that this connector is in the correct orientation is not a problem as it is keyed symmetrically (pin 5 is the key). You will want to make sure that the correctly lined with the header in the harness.

    Step 3: Cut 8 short wires that will be used to connect IDC header to connector

    Step 4. Cut the two long wires. You will need to be able to run these to where you have your color changing module mounted

    Step 5: Hold 9-pin header with helping hands

    Step 6: Solder 8 short wires to header pins
    Note: You will solder wires to pins 1,2,3,4 and 6, 7, 8, 9
    Note: Tinning (putting on solder) the headers and the wires makes attaching them together much easier.

    Step 7: Solder the long wires to header pins. The GI lighting is in pairs: 1-6, 2-7, 3-8, 4-9. Any pair is fine to use.
    Note: Tin the header and wires.
    Note: I connect the short wires on one side of the header pin and the long leads on the other side. When soldering the long leads on, the short wires can fall off when the solder melts. Soldering at a slight upside-down angle (short wires on top), helps keep the short wires in place.
    Note: If you are using a bundled set of wires (as shown), put the heat shrink tubing on before you attach the leads.

    Step 8: Cut and place heat shrink over the wires and exposed pins
    Note: Having different size tubes helps for covering pins with or without the long leads.

    Step 9: Heat and shrink with heat gun

    Step 10: Pin small wires with crimp contacts.
    Note: Try to keep all the pins aligned with one another front/back this makes inserting them into the connector easier.

    Step 11: push pins/push wires into IDC connector
    Note: Needle nose pliers can help pushing the crimp contacts and wires into the connector
    Note: Make sure that you have the crimp contacts aligned correctly before inserting into the connector (see pictures)

    Step 12: Clip the key pin on the header (Pin 5)

    Adding the transistor to the LED backbox circuit:

    Note: Transistors have three pins:
    1. Base/Gate: This is what will take the input from the AC line (after converted to DC). Then there is current to the Base, it will let current through the transistor from the collector to the emitter
    2. Collector: This is connected towards the color changing module (or LED strip)
    3. Emitter: This is connected towards the ground

    Step 1: Find the negative wiring coming from the coloring changing module (or LED string if you don't have a module).

    Step 2: Cut the wire and leave some length going to the module.

    Step 3: Put a piece of heat shrink tubing on both wires and slide away from the splice junction

    Step 4: If you are using TIP122, solder the middle pin (collector) to the wire going to the color changing module

    Step 5: If you are using TIP122, solder the right pin (emitter) to the wire going to the ground.

    Step 6: Slide on the heat shrink tubing, heat, and shrink

    Making the AC->DC converter:

    Note: In order for the transistor to act like a switch, it needs DC current going to its gate. The Gi circuit is AC and cannot trigger the gate on the transistor as it is. It needs to be converted to DC.

    Step 1. Put heat shrink tubing on the long leads coming from the wiring harness (these are a pair of AC wires)

    Step 2: Solder the AC wires to the bridge rectifier. These are very clearly marked. In this example, it is the middle two pins of the bridge rectifier.
    Note: It doesn't matter which way the wires are wired

    Step 3: Cut two short wires (used to link the bridge rectifier to the capacitor)

    Step 4: Solder two short wires to the + and - of the bridge rectifier

    Step 5: Add heat shrink tube, heat, and shrink

    Step 6: Cut two more wires (longer)

    Step 7: Twist and two new wires to the wires coming from the + and - of the bridge rectifier

    Step 8: Slide on heat shrink tube over both of the wires and slide away from the end.

    Step 9: Solder the twisted wires to the capacitor.
    Note: Some capacitors are directional and one sides needs to be solder the positive and the other to the negative

    Step 10: Slide up the heat shrink tube, heat, and shrink

    Step 11: For the free positive wire coming from the capacitor, add heat shrink tubing

    Step 12: Solder the free positive wire coming from the capacitor to the Base/Gate of the transistor.

    Step 13: Slide up heat shrink tube, heat, and shrink

    Step 14: Connect the negative wiring coming from the bridge rectifier to a ground. In this example, I spliced into the ground cable coming from the color changing module (below the transistor).
    Note: Don't forget your heat shrink tube.

    Step 15: Plug in wiring harness, reattach coloring changing module, connect Backbox, and test.

    Step 16: If it works, put it back together and enjoy

    #7 7 years ago

    Description of the problem:

    The transistors in a pinball machine that drive the coils and flashers are acting like switches, and I thought I could use one of them to act as a switch for the backbox LEDs. For example, the transistors powering your flipper coils are normally in an "off" state. When you hit a flipper button, it sends a current to the gate of the transistor, which then allows power to flow through it to activate the coil.

    I though it would be a simple matter of adding a transistor to the circuit driving the backbox LEDs and then using the GI circuit to set the state of the transistor to be on or off. When the GI was on, the backbox LEDs would be on; and when GI off, backbox off. However, what makes this problem a bit more complicated is the LEDs in the backbox are driven by DC, while the GI lights are driven by AC. In order for a transistor to act like a switch, DC current needs to be applied to the gate. AC current will not work.

    Fortunately, there is a relatively easy way to convert AC current to DC current with a bridge rectifier, then to smooth the current with a capacitor to remove the bumps/waves caused by AC. Anyone who knows electronics probably thinks that building the AC to DC converter is pretty basic stuff, but for me, it was my electronics project so I had a lot to learn and figure out. But in the end, it worked.

    Here is the circuit diagram. Again, I'm a complete novice about these things, so please feel free to tell me how to correct it if you find any errors.

    Screen Shot 2014-08-07 at 10.14.51 AM.png

    Breadboard of the circuit
    Testing the circuit. Most things are connected by alligator clips, but the thing worked!

    #8 7 years ago

    Directions (detailed): Stern SAM

    Making the harness:

    Step 1: Locate connector J15 on the I/O Board. This located in the upper-left corner and controls the GI.

    IMG_3184.jpg

    #9 7 years ago

    Step 2: Making sure that this connector is in the correct orientation is not a problem as it is keyed symmetrically (pin 5 is the key). However, you will want to make sure that the correctly lined with the header in the harness.

    Finished harness. Note that there is no bridge wire for pin 5.

    #10 7 years ago

    Unfortunately, I didn't take pictures at each these steps. However, I have detailed pictures for how to make these harnesses in my other how-tos linked a the top of this thread.

    Step 3: Cut 8 short wires that will be used to connect IDC header to connector

    Step 4. Cut the two long wires. You will need to be able to run these to where you have your color changing module mounted

    Step 5: Hold 9-pin header with helping hands

    Step 6: Solder 8 short wires to header pins
    Note: You will solder wires to pins 1,2,3,4 and 6, 7, 8, 9
    Note: Tinning (putting on solder) the headers and the wires makes attaching them together much easier.

    Step 7: Solder the long wires to header pins. The GI lighting is in pairs: 1-6, 2-7, 3-8, 4-9. Any pair is fine to use.
    Note: Tin the header and wires.
    Note: I connect the short wires on one side of the header pin and the long leads on the other side. When soldering the long leads on, the short wires can fall off when the solder melts. Soldering at a slight upside-down angle (short wires on top), helps keep the short wires in place.
    Note: If you are using a bundled set of wires (as shown), put the heat shrink tubing on before you attach the leads.

    IMG_3153.jpg
    #11 7 years ago

    Step 8: Cut and place heat shrink over the wires and exposed pins
    Note: Having different size tubes helps for covering pins with or without the long leads.

    IMG_3154.jpg
    #12 7 years ago

    Step 9: Heat and shrink with heat gun

    IMG_3155.jpg
    #13 7 years ago

    Step 10: Pin small wires with crimp contacts.
    Note: Try to keep all the pins aligned with one another front/back this makes inserting them into the connector easier.

    IMG_3159.jpg
    #14 7 years ago

    Step 11: push pins/push wires into IDC connector
    Note: Needle nose pliers can help pushing the crimp contacts and wires into the connector
    Note: Make sure that you have the crimp contacts aligned correctly before inserting into the connector (see pictures)

    Step 12: Clip the key pin on the header (Pin 5)

    IMG_3158.jpg
    IMG_3160.jpg
    IMG_3161.jpg

    #15 7 years ago

    The wiring harness is complete.

    #16 7 years ago

    Adding the transistor to the LED backbox circuit:
    Note: Transistors have three pins:
    1. Base/Gate: This is what will take the input from the AC line (after converted to DC). Then there is current to the Base, it will let current through the transistor from the collector to the emitter
    2. Collector: This is connected towards the color changing module (or LED strip)
    3. Emitter: This is connected towards the ground

    Screen Shot 2014-08-07 at 8.39.25 PM.png
    #17 7 years ago

    Step 1: Find the negative wiring coming from the coloring changing module (or LED string if you don't have a module).

    Step 2: Cut the wire and leave some length going to the module.

    Step 3: Put a piece of heat shrink tubing on both wires and slide away from the splice junction

    Step 4: If you are using TIP122, solder the middle pin (collector) to the wire going to the color changing module

    Step 5: If you are using TIP122, solder the right pin (emitter) to the wire going to the ground.

    Step 6: Slide on the heat shrink tubing, heat, and shrink

    IMG_3150.jpg IMG_3151.jpg IMG_3146.jpg
    #18 7 years ago

    Making the AC->DC converter

    Note: In order for the transistor to act like a switch, it needs DC current going to its gate. The Gi circuit is AC and cannot trigger the gate on the transistor as it is. It needs to be converted to DC.

    #19 7 years ago

    Step 1. Put heat shrink tubing on the long leads coming from the wiring harness (these are a pair of AC wires)

    Step 2: Solder the AC wires to the bridge rectifier. These are very clearly marked. In this example, it is the middle two pins of the bridge rectifier.
    Note: It doesn't matter which way the wires are wired

    IMG_3162.jpg IMG_3163.jpg IMG_3164.jpg
    #20 7 years ago

    Step 3: Cut two short wires (used to link the bridge rectifier to the capacitor)

    Step 4: Solder two short wires to the + and - of the bridge rectifier

    Step 5: Add heat shrink tube, heat, and shrink

    Step 6: Cut two more wires (longer)

    Step 7: Twist and two new wires to the wires coming from the + and - of the bridge rectifier

    Step 8: Slide on heat shrink tube over both of the wires and slide away from the end.

    Step 9: Solder the twisted wires to the capacitor.
    Note: Some capacitors are directional and one sides needs to be solder the positive and the other to the negative

    Step 10: Slide up the heat shrink tube, heat, and shrink

    IMG_3165.jpg
    #21 7 years ago

    Time to connect the harness to the transistor and complete the circuit!

    Step 11: For the free positive wire coming from the capacitor, add heat shrink tubing

    Step 12: Solder the free positive wire coming from the capacitor to the Base/Gate of the transistor.

    Step 13: Slide up heat shrink tube, heat, and shrink

    Step 14: Connect the negative wiring coming from the bridge rectifier to a ground. In this example, I spliced into the ground cable coming from the color changing module (below the transistor).
    Note: Don't forget your heat shrink tube.

    Untitled.001-77.png Untitled1.002.png
    #22 7 years ago

    Step 15: Plug in wiring harness, reattach coloring changing module, connect Backbox, and test.

    Step 16: If it works, put it back together and enjoy

    #23 7 years ago

    Here is how I have the harness strung and color changing module attached in the backbox. The wires from J15 run up and over the top using the existing wire holders, then I have the color changing module (with AC->DC converter) mounted in the upper right. I have the antenna for the color changing module taped with electrical tape to keep in pointing towards the translite with the hope that the IR remote can send it signals more easily.

    IMG_3186.jpg
    IMG_3188.jpg

    #24 7 years ago

    That is pretty much it. I may have missed something in this writeup because of my lack of pictures, so please post any questions. Also, advice on how to make this better or easier is always appreciated.

    #25 7 years ago
    Quoted from MustangPaul:

    WOW!!! That is REALLY something.

    Thanks!

    #28 7 years ago
    Quoted from Out-West:

    A "GI buddy" from DK pinball might be easier to control the 12v with gi circuit.

    That's really neat in a nice small package. Overall, it is basically the same thing as what is described here (look at their circuit diagram -- bridge rectifier and capacitor), but as Out-West pointed out, you'll want to use a transistor to drive the LEDs in the backbox. Also, you'll need to still to build a harness to tap into the GI.

    6 months later
    #30 6 years ago
    Quoted from Jasontaps:

    Thanks for these directions Eric.
    Here is a diagram I created using your directions
    I just finished mine last night.
    Wiring Diagram.jpg (Click image to enlarge)

    Nice work!

    #33 6 years ago
    Quoted from BR80:

    I don't have a Tron, but this is one great DYI write-up. Thanks for taking the time to document everything with the step by step walk through. Missed this thread when you started it 6 months ago, glad it got bumped. Not enough recognition for everything put into this project. Thumbs up here!

    Major thanks! I have a set of them posted on pinside (search for DIY), and some more if you are interested in using Arduinos and addressable LEDs to brighten up a game: http://goo.gl/TwQRp8



    2 years later
    #35 3 years ago

    Perhaps driving too much current through the transistor or a short? The TIP142T collector can handle 10A and the base 0.5A: http://www.st.com/content/ccc/resource/technical/document/datasheet/6d/08/86/eb/dc/af/41/f5/CD00000917.pdf/files/CD00000917.pdf/jcr:content/translations/en.CD00000917.pdf. However, 10A is enough to drive 10 meters of LEDs. . .

    Did the LEDs work when driven straight off the 12V?

    #37 3 years ago

    Did the transistor short out?

    #39 3 years ago
    Quoted from foxicp:

    i tested the transistor and it is dead . other components seems to be ok.

    If you have another transistor, try it again. Maybe a bum component. Of course, double check the circuit and see if there is the possibility of a short somewhere.

    #41 3 years ago
    Quoted from yaheath:

    That circuit needs a resistor in front of the transistor's base. Otherwise, there's nothing to prevent the base current from exceeding the maximum that it can handle. The TIP142T datasheet says the maximum is 500mA, but that transistor should saturate at a much much lower base current (e.g. 2mA).
    I would put a 2.2K ohm resistor (1/4W) in between the capacitor's positive terminal and the transistor's base pin. That'll limit the base current to ~3mA (assuming 7vdc across the capacitor).

    Excellent!

    #44 3 years ago

    Great to hear. The length of time thE LEDs stay on is due to the capacitance of the capacitor. Use a smaller one and the lights will cut out sooner (or remove for an instant off).

    8 months later
    #53 3 years ago

    Just pull 12V from J118. I’m betting that you aren’t getting 12VDC from the 6.3AC used for the GI. Have you measured the voltage with a multimeter?

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