Announcement

Collapse
No announcement yet.

Generic Tech Device Section For HomeBrew Pinball.

Collapse
This is a sticky topic.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Thanks Mr [MENTION=11194]kress[/MENTION]. What on time do you use? I was thinking of adding a 10 turn pot for fine tuning? I was thinking more for firing solenoids.
    Cheers Trev

    Sent from my SM-G930F using Tapatalk

    Comment


    • #17
      [MENTION=1535]thegrunta666[/MENTION] these are the mosfet boards I'm going to try on the Thomas Pinball.
      Ebay item number 191736193072
      Cheers Trev

      Sent from my SM-G930F using Tapatalk

      Comment


      • #18





        Well that will work however I think 1 second will result in a lot of switches not scoring but I think the biggest problem is just how many of those circuits you will need for a machine.

        I think a better approach would be to use that 555 timer to make an astable timer to make the clock pulse to run a collection of MC14490.

        Each MC14490 gate will do exactly the same thing but you get 6 switches per chip that way.

        As quoted from the data sheet of the MC14490....

        "The digital contact bounce eliminator circuit takes an input signal from a bouncing contact
        and generates a clean digital signal four clock periods after the input has
        stabilized. The bounce eliminator circuit will remove bounce on both the
        “make” and the “break” of a contact closure.
        The clock for operation of the MC14490 is derived from an internal R-C oscillator which requires
        only an external capacitor to adjust for the desired operating frequency (bounce delay). The clock may also be driven from an external clock".

        That external clock can be the 555 timer and your time interval can be controlled by adjusting the R-C network pot.

        The time interval of de-bounce on the MC14490 is the length of "4 clock pulses". Slowing down the pulses created by the 555 astable circuit will lengthen the time the 6 switches connected to it will de-bounce.

        That one 555 astable circuit could be used to drive the clock pulse input on multiple MC14490 chips and each chip can do 6 circuits.

        10 X MC14490 chips is nearly the 64 switches a pinball can decode. Doing this with indervidual 555 circuits would require 60 X 555 timer circuits but while the indervidual 555 circuit can have it's de-bounce duration adjusted by itself, the MC14490 cannot but neither can a pinball machine board.

        Is it now becoming apparient why I have choosen to use a cheap old pinball board set for a homebrew?.

        Just kidding. That answer has more to do with my hatred of software and love of hardware than anything else.

        I'm actually digging into this subject for my own use as things become more complete I build and this would save me building multiple de-bounce circuits per project like i have always done in the past.

        Comment


        • #19
          Originally posted by thegrunta666 View Post
          Great web store! Has some 'weird' but 'must have' props, for the wanna be 'Master Criminal'...
          Last edited by nmercury; 3rd July 2017, 08:56 PM.

          Comment


          • #20
            Originally posted by BIG Trev View Post
            255 sound wav board on Ebay (item number 222180828182)
            It has 8 input lines that can be used in any combination to play all the sounds that are stored on an SD card. It doesn't have serial input but uses a binary input to access each sound.
            For example. Inputs 2 and 5 would play sound 34.

            Sent from my SM-G930F using Tapatalk
            I'm going to use a 74ls595 serial to parallel shift out register ic to drive the sound board. The 74ls595 will go through two 74ls06 hex inverters (8 bits) then to the sound board as the sound inputs are active low.
            https://www.arduino.cc/en/Tutorial/ShiftOut
            I suppose you could drive leds this way too as shown in the examples.
            Cheers Trev

            Sent from my SM-G930F using Tapatalk

            Comment


            • #21
              Originally posted by BIG Trev View Post
              I'm going to use a 74ls595 serial to parallel shift out register ic to drive the sound board. The 74ls595 will go through two 74ls06 hex inverters (8 bits) then to the sound board as the sound inputs are active low.
              Cool, let me know how this board goes as it really appears to be a good, cheap solution.

              My intention is to use it to replace a Williams sound board and use the sound triggers off the MPU board/ driver board off the Williams board set to drive the sound board inputs direct.

              Once I work out how to replace the Williams sound board I see no reason why the sounds can't be replaced on all early Williams pinballs.

              Comment


              • #22
                Originally posted by Autosteve View Post





                Well that will work however I think 1 second will result in a lot of switches not scoring but I think the biggest problem is just how many of those circuits you will need for a machine.

                I think a better approach would be to use that 555 timer to make an astable timer to make the clock pulse to run a collection of MC14490.

                Each MC14490 gate will do exactly the same thing but you get 6 switches per chip that way.

                As quoted from the data sheet of the MC14490....

                "The digital contact bounce eliminator circuit takes an input signal from a bouncing contact
                and generates a clean digital signal four clock periods after the input has
                stabilized. The bounce eliminator circuit will remove bounce on both the
                “make” and the “break” of a contact closure.
                The clock for operation of the MC14490 is derived from an internal R-C oscillator which requires
                only an external capacitor to adjust for the desired operating frequency (bounce delay). The clock may also be driven from an external clock".

                That external clock can be the 555 timer and your time interval can be controlled by adjusting the R-C network pot.

                The time interval of de-bounce on the MC14490 is the length of "4 clock pulses". Slowing down the pulses created by the 555 astable circuit will lengthen the time the 6 switches connected to it will de-bounce.

                That one 555 astable circuit could be used to drive the clock pulse input on multiple MC14490 chips and each chip can do 6 circuits.

                10 X MC14490 chips is nearly the 64 switches a pinball can decode. Doing this with indervidual 555 circuits would require 60 X 555 timer circuits but while the indervidual 555 circuit can have it's de-bounce duration adjusted by itself, the MC14490 cannot but neither can a pinball machine board.

                Is it now becoming apparient why I have choosen to use a cheap old pinball board set for a homebrew?.

                Just kidding. That answer has more to do with my hatred of software and love of hardware than anything else.

                I'm actually digging into this subject for my own use as things become more complete I build and this would save me building multiple de-bounce circuits per project like i have always done in the past.
                The on time is determined by the rc network pins 6 and 7
                I use these as a 100ms one shot.555 timers I think can run at about 3 megahertz these days so timers of microseconds can be achieved.
                fOr No rAIsOn

                Comment


                • #23
                  Originally posted by kress View Post
                  The on time is determined by the rc network pins 6 and 7
                  I use these as a 100ms one shot.555 timers I think can run at about 3 megahertz these days so timers of microseconds can be achieved.
                  Problem using a 555 is it can re-trigger within the outout span (Different from being held on).
                  You'd be better using 74hc221 for 100ms, As they are a Dual non-retriggerable monostable multivibrator with Schmitt-trigger input (b).

                  Comment


                  • #24
                    Your not going to get a much simpler circuit. It is using just one of the 6 gates found in either a 4049 or 4050, depending on whether you require switching to low or high), and a handful of passive parts.



                    Your time is set by the value of C1 and R2 however for really small delay periods, as CMOS chips always have a small resistor already on the inputs, you can do without R2.

                    Comment


                    • #25
                      Originally posted by ozfalcon View Post
                      Problem using a 555 is it can re-trigger within the outout span (Different from being held on)
                      .
                      You'd be better using 74hc221 for 100ms, As they are a Dual non-retriggerable monostable multivibrator with Schmitt-trigger input (b).
                      I don't want to be pedantic but in regards to the 555
                      Circuit you are wrong, all pulses inside the timed output window are ignored.
                      The circuit wasn't handed over in speculation that it might
                      work it actually works.
                      I have used this circuit mainly for pop bumpers in several pinballs.
                      Also a 555 can drive a relay or power Transistor without a buffer circuit...don't underestimate the mighty 555
                      fOr No rAIsOn

                      Comment


                      • #26
                        Originally posted by Autosteve View Post
                        Your not going to get a much simpler circuit. It is using just one of the 6 gates found in either a 4049 or 4050, depending on whether you require switching to low or high), and a handful of passive parts.



                        Your time is set by the value of C1 and R2 however for really small delay periods, as CMOS chips always have a small resistor already on the inputs, you can do without R2.
                        Yes, That is the classic debounce. You can also invert it with a simple transistor.
                        Click image for larger version

Name:	74hc221_InvertDebounce.png
Views:	1
Size:	11.6 KB
ID:	1821684

                        - - - Updated - - -

                        Originally posted by kress View Post
                        I don't want to be pedantic but in regards to the 555
                        Circuit you are wrong, all pulses inside the timed output window are ignored.
                        The circuit wasn't handed over in speculation that it might
                        work it actually works.
                        I have used this circuit mainly for pop bumpers in several pinballs.
                        Also a 555 can drive a relay or power Transistor without a buffer circuit...don't underestimate the mighty 555
                        Do be pedantic, I thought they were re-triggerable.

                        Comment


                        • #27
                          Just to add to the debounce discussion, Here is the link to "A Guide to Debouncing"

                          A must read for this topic.

                          Comment


                          • #28
                            Originally posted by ozfalcon View Post
                            Just to add to the debounce discussion, Here is the link to "A Guide to Debouncing"
                            That's a really useful resource, thanks for that!

                            Michi.
                            May the pinballs tumble in your direction!

                            Comment


                            • #29
                              Originally posted by ozfalcon View Post
                              You can also invert it with a simple transistor.
                              [ATTACH=CONFIG]112841[/ATTACH]
                              Some helpful notes about this debounce circuit.
                              I use the inverted version - So I like to limit/sink @1mA (Hence the 5k resistor @ R1)

                              For ease of use (Lazy), I substitute capacitors for approximate timing.
                              1.00uF = ~40mS
                              0.47uF = ~20mS (Recommended for general use)
                              0.22uF = ~10mS

                              Comment


                              • #30
                                I found this circuit for driving large seven segment leds from an Arduino.


                                Sent from my SM-G930F using Tapatalk
                                Last edited by BIG Trev; 14th July 2017, 03:26 PM.

                                Comment

                                Users Viewing Topic: 0 members and 1 (guests)
                                Working...
                                X