Revamping Old School Pinball with an ESP32 -- Episode-632

Mark had the opportunity to work on a vintage pinball machine from 1972. This machine, belonging to a friend, required some repairs, and Mark willingly took on the challenge. Before delving into the repairs, he provided a glimpse into the unique characteristics of vintage pinball machines. Lacking transistors, these machines rely on coils, relays, and two motors—one for moving a target left to right and another for driving a pulse wheel. 

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Revamping Old School Pinball with an ESP32 -- Episode-632

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Discovering Defects 

Unveiling the intricate mechanism, Mark encountered a few defects: the score counter for player two wasn't resetting, the machine produced excessive mechanical noise during initialization, and the right flipper exhibited constant overpowering, causing the coils to heat up. With over 100 relays and numerous contacts, pinpointing the issue initially seemed daunting. Fortunately, the pinball machine came with a schematic, allowing Mark to identify and repair three broken relay contacts. 

Innovative Sound Upgrade 

While contemplating these repairs, the idea of upgrading the pinball machine struck Mark. After a swift repair job that felt almost disproportionate to the effort invested, he discussed the possibility of an upgrade with the friend, keeping the specifics a surprise. The concept involved integrating sound, triggered by the ball hitting various targets and switches during gameplay. To tap into these signals without interference from the pinball's electrical chaos, Mark devised a special trigger board equipped with optocouplers and an optical transceiver. 

Challenges and Solutions 

Implementing the trigger board, Mark faced challenges, particularly with the optocouplers' rapid response creating unwanted signal fluctuations. Various attempts, including adding capacitors to stabilize the input signals, proved insufficient. As time pressed on, he opted for a pragmatic solution—adding more relays to physically separate the pinball signals from the microcontroller. This extra board successfully circumvented interference issues and provided a crucial reminder: real-world implementation often differs from simulations. 

Audio Innovation and Conclusion 

To enhance the gaming experience, Mark explored different methods of playing audio files using embedded systems. Options like Arduino with an SD card proved inadequate due to poor sound quality, while an Arduino Uno with an MP3 shield had undesirable latency. A one-size-fits-all MP3 trigger board shared similar latency concerns. Opting for an ESP32 with an external DAC and SD card provided acceptable latency and superior sound quality. This choice, influenced by previous successful projects, encapsulates the adaptability required for vintage technology. In the end, the pinball machine received not just repairs but a modern audio twist, showcasing the delicate balance between preserving nostalgia and embracing contemporary innovation. 

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