Kaizen Posted September 29, 2019 Share Posted September 29, 2019 (edited) I just knocked up this Jamma pass through PCB which allows you to add credits by holding button 1 and pressing either the P1 or P2 button. The output goes to the Service input pin on the game board. https://drive.google.com/open?id=14Tg_6zshCgoTofXGC1SW6LCf4-aqCPvT The image and video explains whats happening in the circuit above and I've built and tested it with no issues. Then I got to thinking this could possibly be done with a 74LS74 but was wondering what needs to happen with the outputs which would be tied HI via the pull ups on the game board and one flip flop's output is LO when the other flip flop's output is HI if they are both connected to the same Service input pin on the game board. Any thoughts on how to achieve the same result as the above schematic with a single chip? Edited September 30, 2019 by Kaizen Link to comment Share on other sites More sharing options...
hvc01 Posted September 29, 2019 Share Posted September 29, 2019 Can u just wire outputs from 1st 2 nor gates into 3rd? That way u lose the other chip Link to comment Share on other sites More sharing options...
Kaizen Posted September 29, 2019 Author Share Posted September 29, 2019 (edited) Can u just wire outputs from 1st 2 nor gates into 3rd? That way u lose the other chip Simulation says it will work, thanks mate... PCB redesigned with a single chip. Edited September 29, 2019 by Kaizen Link to comment Share on other sites More sharing options...
Kaizen Posted September 30, 2019 Author Share Posted September 30, 2019 (edited) So here's the updated schematic, such a simple circuit and I'm surprised no one has done it this way before. I did some searching and couldn't find anything. I've drawn up a board that can be screwed to the inside of the cabinet and connects through a header so if you want to disable it you just pull the connector off. The bare board costs $0.40 when you order 10, shipping not included but if putting another order through it's worth adding them in. All parts available from Jaycar for a total of $3.40... I knocked up a prototype on Vero and tested this afternoon. Gerber File Edited September 30, 2019 by Kaizen Link to comment Share on other sites More sharing options...
hvc01 Posted September 30, 2019 Share Posted September 30, 2019 i'll have to get one for my cocktail, sick of feeding in quarters :) Link to comment Share on other sites More sharing options...
Kaizen Posted October 11, 2019 Author Share Posted October 11, 2019 (edited) Credit PCBs arrived today, both tested and working. I could only order 30 of the small PCBs in a small batch order otherwise it would have taken a few more days before they would arrive. All boards are sold but will order more the next time I order some PCBs and put up a sale thread. If anyone wants some let me know (no commitment) and it'll help me order enough next time. Edited October 12, 2019 by Kaizen 2 Link to comment Share on other sites More sharing options...
taito Posted December 23, 2019 Share Posted December 23, 2019 This is kick ass mate! :) Elegant solution! Link to comment Share on other sites More sharing options...
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