Arcade Collecting > Pinball

Optical Pinball Plunger Circuit for MAME machine?

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bdeshazer:
Apologies in advance to the pinball purists, it looks like this board is primarily used for the discussion of real Pinball machines and not emulation, but it seemed the best place for this post.

I found this simple circuit for building an optical switch for detecting a pinball plunger pull here:

http://www.johnsretroarcade.com/hardware_pinball.asp

The Sharp GP2L24 Reflective Opto-switch he said he used is discontinued. There is an image at the link that references QRB1133/QRB1134, and searching on mouser.com for QRB1133 shows that it is discontinued as well, but there is a "similar product" link that points to this active product:

http://www.mouser.com/search/ProductDetail.aspx?R=828-OPB703WZ

That looks to me like it should work as a replacement but figured I would check here to see if a) anyone has built this or a similar circuit and b) whether anyone had any opinions on this substitution part.

I tried using the "contact" form on the site to e-mail John but the mail script he is using is broken.

I know I could use a simple switch contact for this, but the chances of mechanical failure seem much more likely and frequent than the solution this circuit provides.

Thanks!

drventure:
Using a standard mechanical switch (like in typical buttons) but with a roller on it, you can mount that such that it engages when the plunger is pulled back, and it basically gives you the same effect, and so far it's been quite solid.

But that circuit is pretty interesting.

Q*Bert_OP:
How about a magnetic reed switch?

bdeshazer:
Thanks for the replies guys, but I really want to avoid a mechanical switch if I can.

I'm aware of the NanoTech kit at http://nanotechent.com/mot-ionkit.php but do not need that kind of accuracy for my casual game play and I don't want to spend another $140 on my MAME machine when a $10 "good enough" circuit will probably do for me.

Guess I'll just order the parts I need (probably just the opto as I think I have everything else on hand) and give it a try!

drventure:
You know, reading through that circuit description again, i believe it's probably overkill if you're using an IPAC.

The reason is that the IPAC already has debounce functionality built in (after all, standard arcade button switches can bounce too).

So really, all that should be necessary is a typical IR transmitter receiver pair.

http://www.radioshack.com/product/index.jsp?productId=2049723

You'd hook the button leads through the reciever, such that presence of IR light on it would "close it". Then mount so that it receiver can't see the emitter normally (and the circuit would be open), but pull back the plunger and the circuit closes.

Now, as for the circuit itself?

I'm no EE, so I just googled IR beam break detector and came up with tons of hits

Here's one

http://pcbheaven.com/circuitpages/IR_Short_Distance_Beam_Cut_Detector/

Essentially, instead of powering an LED to indicate the beam break, youd connect the "button" across it to drive the input to the IPAC.

There's probably better (or more applicable) circuits out there, but I thought that one was interesting because it uses a timer to modulate the IR signal so that stray IR sources (sun, lamps, etc) won't set it off.

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