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?
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.
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
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.
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.
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.