FreePlay 555 Coin Circuit
My Sega Star Trek Captain’s Chair is destined to be present at the 2012 Texas Pinball Festival. As a result; the game needs to have a FreePlay feature (IE a way for the public to play the game without needing quarters). I know Sega Star Trek has a freeplay rom hack available; however, at this moment, VectorLabs isn’t supplying freeplay roms with their devices. I haven’t spent enough time with the multi-vector boardset to determine how easy/hard it would be to convert to Freeplay. As a result; I wanted a simple inexpensive way to credit up the machine when the user pressed the Start button (1UP).
I toyed with the idea of using a cheap 8pin ATMEL microcontroller; but decided a simple 555 timer could be developed to do most of the heavy lifting. In the end I decided to go with a dual 555 timer (NE556) in a cascaded mono-stable configuration. The circuit features:
- PowerOn Reset to “credit up” a single credit when power is applied to the machine. Jumpered feature.
- Ability to drive COIN_NO signals
- Ability to “interrupt” COIN_NC
- Can be alternatively stuffed for AC power supplies (6.3VAC GI circuits in Pinball Coindoors).
- Jumper configuration to “disable” circuit.
- Barrier Diodes to help prevent “installation error”.
I have decided to release this design under to the public under the TAPR Non-Commercial Open Hardware License which indicates:
You may make products based upon this design, provided you do not make more than ten units in any twelve month period for your personal use.
Sounds like a great way to go. Now if I just had that Elvis Pinball Machine, that my Sisters family had, back when the kids were growing up... I was allot of fun to play, when we would get together on the Holidays:)
- Using 555 timers to add “free play” functionality to classic arcade machines
- Using 555 timers to add “free play” functionality to classic arcade machines - Hack a Day
- FreePlay 555 Coin Circuit | Zitt's Blog