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| Q*bert- Because who was alive in 1982 and doesn't want one?! |
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| PL1:
--- Quote from: bobbyb13 on July 17, 2022, 02:16:29 am ---As I was playing with the thing after I built it, it occurred to me that I wasn't sure how this thing really needed to be hung in the cabinet. Oriented to have the plunger fall back on it's tail in the bracket? (plunger pointing straight up?) How do these things sit in a real cabinet? --- End quote --- Mount the bracket so the small gap is toward the top coil wires are toward the bottom of the cab and the wood block on your bracket is toward the top. - Plunger fires up then gravity pulls the plunger down. Scott EDIT: Comparing your bracket to the original, you've got the larger gap on the top instead of the bottom so there's less room for the plunger to travel and reset. When the coil is energized, the electromagnetic field pulls the metal part of the plunger to the center of the coil which pushes the nylon end out of the coil. Can you turn the plunger 180 degrees and mount your bracket with the wood block down? That way, the nylon end of the plunger will hit the metal bracket on the smaller gap side when the coil fires and the plunger will travel further. |
| bobbyb13:
Ah, yes. You are correct! At least that fix doesn't require bending another bracket. Still seems as if the plunger should be striking something other than the bracket given the noise I have always heard from them, but I will give this a go. |
| PL1:
--- Quote from: bobbyb13 on July 17, 2022, 02:24:36 pm ---Still seems as if the plunger should be striking something other than the bracket given the noise I have always heard from them, but I will give this a go. --- End quote --- The impact of the plunger on the bracket transmits vibration to the coinbox (or cab side-panel if you don't have a coinbox) which acts as a resonant chamber. When you knock on drywall to locate a stud, you'll get different results knocking between the studs vs. knocking on the stud -- same knuckle, same drywall, different location ==> different sound. While you're testing, try it without a screw through the bottom of the bracket since securing both ends of the bracket might not transmit the vibration as effectively. ;) Scott |
| pbj:
Plunger should fall down on a piece of rubber from gravity after it fires. just glue a cabinet bumper or something at the bottom of that thing. |
| bobbyb13:
In between chores I stole time to work on the knocker. I decided it would be a good idea to wire it up to the power supply/iso trans bench unit I made and fire this thing to see the throw of the plunger so I could relocate the coil to the right spot, and facing the right direction. Funny how many people post things to youtube that are only half right, yeah? --- Quote from: PL1 on July 17, 2022, 04:02:53 pm --- --- Quote from: bobbyb13 on July 17, 2022, 02:24:36 pm ---Still seems as if the plunger should be striking something other than the bracket given the noise I have always heard from them, but I will give this a go. --- End quote --- The impact of the plunger on the bracket transmits vibration to the coinbox (or cab side-panel if you don't have a coinbox) which acts as a resonant chamber. When you knock on drywall to locate a stud, you'll get different results knocking between the studs vs. knocking on the stud -- same knuckle, same drywall, different location ==> different sound. While you're testing, try it without a screw through the bottom of the bracket since securing both ends of the bracket might not transmit the vibration as effectively. ;) Scott --- End quote --- I had been thinking about this all along and what I saw for videos from people in regard to sound bugged me (although they were informative otherwise!) Part of the sound that we are all used to hearing is the plastic part of the plunger hitting a pinball machine wood back box itself (not even a bracket.) Sometimes there is a plate to prevent wear on the box. That makes for a nice resonant chamber and gives a good amount of mass that the plunger is striking. I have been designing this along the lines of an original Q*bert knocker but don't like the idea of the plunger just hitting the bracket- hence the block of ply to get rid of the tinny sound of hitting metal. After a few tries I found what looked like a good spot for the coil, flipped it the way I wanted it and the plunger to face and then drilled fresh holes. --- Quote from: pbj on July 17, 2022, 04:47:57 pm ---Plunger should fall down on a piece of rubber from gravity after it fires. just glue a cabinet bumper or something at the bottom of that thing. --- End quote --- Absolutley correct of course. I started with a double wrap of rubber electrical tape but it still wasn't enough to get rid of the rebound noise so it got a little bit of weatherstrip foam too. That makes it pretty much silent. I was satisfied with bench testing so figured it was time to put it in. Of course I couldn't find the kind of fuse holder I wanted to use so had to settle for this in-line thing short term anyway. Mounted bracket, put in slow blow 1 amp fuse, wired to terminal J on the jamma harness and 12v on the power supply and bingo. Even mounted like this it makes a pretty satisfying 'thwack!' when it is supposed to. I had entertained the idea of having it mounted to strike the underside of the monitor chassis shelf (which I might do) but if the sound continues to deepen as I finish the bezel and rear door (as I am sure it will) then it might just stay where it is. Take that Coily. |
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