Air Hockey Scoreboard

Discussion in 'The Projects Forum' started by zzz_tired, Nov 12, 2011.

  1. zzz_tired

    Thread Starter New Member

    Nov 12, 2011
    5
    1
    I built an air hockey table with my friend but it didn't come with a score board.
    So I found some extra garage door safety sensors laying around, and I figured I could some how use them to make a counter with some 8 segment displays.

    Problem is, I have no idea HOW to make a circuit from scratch, and circuits from most websites seem pretty unreliable.
    (This forum seems like a good place to start from what I saw)
    Anyways...(back on topic), could one of you guys come up with a circuit that could use these sensors (as the puck passes through them) to keep score of the game as we (my friend and I) play air hockey.

    *edit
    I am currently learning electronics at a trade school so I have parts in shop that I can use
     
    Last edited: Nov 12, 2011
  2. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Welcome to AAC!

    I can help you, but before diving into this, could you post a simple drawing or schematic of what you have in mind, e.g., how many digits (max number of points) per side, timer and length of time and buzzer, if any, etc. Like your instructors at school, we like to see some work on your part instead of just giving you the answer so you learn in the process. This will be a great project to go with your studies.
     
  3. zzz_tired

    Thread Starter New Member

    Nov 12, 2011
    5
    1
    I'll attempt one, but I'm sorry if its too simplistic. I want it to go 1~9 and then have a button or switch to reset it...(I dont really know how to make circuits from scratch...so sorry if it sucks)
     
  4. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    No problem, that's a good start. Also note these are usually referred to as 7-segment displays, not eight although most of them have 7 segments and a decimal point.

    We have many people who request a completed project without providing much detail or showing any work and who almost never answer questions for more detail. Since you're studying electronics and building a circuit is challanging in itself for someone new to it, I'll put together a schematic for you. This is a fairly straightforward circuit, so give me a couple of days and let me ask a a few questions.

    Questions:

    1) 0-9 points per side, correct?

    2) What is the operating voltage (and if you can measure it the current draw) of the garage door sensors you are using?

    3) What is the voltage output of the sensor when the sensor is not tripped?

    4) What is the voltage output of the sensor when it is tripped (something is blocking the path)?

    5) Have you tested to see if the sensor can be tripped by the puck at the distance you plan to keep the transmitter and receiver apart?

    6) How big do you want the digits to be? Common 7-segment displays are 0.56" high, but some people like making big digits to look more like those found at sporting events. A bigger display is doable, but will require more parts and time to build. I think you just want a simple display to start with, but I want to ask to be sure.

    7) Any other features? What you have is plenty - just be warned I am an engineer and often follow the motto "If it ain't broke, it doesn't have enough features.". :D

    Reset button is easy with the right IC and I have just the one in mind. You can look at the datasheet for the CD40110. Many 7-segment display circuits built with discrete logic (vs. microcontroller) use two ICs, one to change a clock input into binary-coded decimal (BCD) and one to change the BCD to 7-segment output. The CD40110 performs both of these functions in one IC and it has a reset input.
     
  5. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Okay, here you go. The CD4093 is used as a switch debounce so nice, clean pulses go to the CD40110s preventing the counter from jumping. As I do not know anything about the sensors you plan to use, I've added NPN transistors in case the output voltage is below 12V. Other voltages can be used to power this circuit, but let me know if 12V won't work so I can make any necessary changes.
     
    zzz_tired likes this.
  6. zzz_tired

    Thread Starter New Member

    Nov 12, 2011
    5
    1
    sorry for responding late
    1. yes
    2-4 I couldn't find a lot of info about the sensor, it wasn't on the package, and I'm not very good at finding product information otherwise.
    5. no, but if it doesn't work at the distance I want, I already have a back up plan.
    6. atm I'm using a small display
    7. atm I'm just trying to streamline
    I'll edit later for more information about the sensors
     
    Last edited: Nov 16, 2011
  7. zzz_tired

    Thread Starter New Member

    Nov 12, 2011
    5
    1
    Sorry for posting late, and if I am currently breaking a rule I see on most forums(double posting) I have been busy with shop fair at my school, so I haven't had much extra time.
    Anyways...the sensors run at around 5V~8V, and the change in voltage varied from what I measured. Alone its about a .5V change and if a load is applied its around 2.5V change.

    *edit: I got this info by testing them during shop and if you are wondering why I had time for this, I am programming one of the schools boebot's using basic stamp to be a scoreboard...I already found out that it works as a variable resistor and I cannot program it in. This project (on the forums) is a way to have a scoreboard after shop fair since I can't keep boebots.
     
  8. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Adding additional information regarding your post is never a bad thing, no worries. :)

    Ah, the BOEBOT, it's been years since I've tinkered with mine. Many fond memories from my college days . . .

    Okay, I need a little more explanation on the sensors.

    1) When you say the sensors run between 5-8V, do you mean you apply between 5-8V to get them to operate?

    2) When you say the change in voltage, is this a change in voltage from the receiver (I assume you have a transmitter and a receiver, please correct me if I'm wrong).

    3) When you say load and no load, do you mean when you block the beam (load) and when you leave the beam undisturbed (no load)?

    4) If there is a dedicated receiver and transmitter, what is the voltage output of the receiver when a) you don't block the beam and b) when you block the beam with a puck? When measuring this, it would be ideal to position the transmitter and receiver the same distance apart as you plan when in the hockey table. I'm guessing this will be about 8-10 inches.

    5) If possible, could you take a picture of the sensors and post it here?

    If you limit the max voltage to 5VDC using a voltage divider (done with two resistors), I think you could use the sensor with the Basic Stamp using the POT command if I remember correctly - just if you want to play with the sensors and Basic Stamp.
     
  9. zzz_tired

    Thread Starter New Member

    Nov 12, 2011
    5
    1
    1. yes, the transmitter needs a minimum of 5V to run
    2. It's the receiver
    3. what i meant by load is a resistor, I was using it as a voltage drop (if...im using terminology correctly...)
    4. with resistor (tested on a boebot with a DMM) a: about 5V b: about 2.5V
    5. got an image off of google...


    oh I didn't know that,I just taught myself how to use a boebot two days ago, so I didn't really know a lot of commands. I had fun using one, I might try tinkering with it.
    Only problem, the calculated change in resistance on the receiver is about 100Ω(if I remember right)...so I don't know if that'll still work.
     
    Last edited: Nov 18, 2011
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