Arcade Collecting > Miscellaneous Arcade Talk

Reproduction Atari Volcano Switch Voltage

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--- Quote from: Zebidee on January 25, 2022, 05:28:42 am ---There was a Facebook thread recently on volcano buttons and I mentioned the need to use a resistor with them, but somebody else commented that they now have a resistor built-in. Not a great authority, but there you are.

One thing we do know is that you can add another resistor, or use a higher value resistor, without breaking anything. The LED will probably still light, but with slightly lower brightness. Worst that can happen is the LED won't light.

--- End quote ---
That is consistent with the YT video above and Drakkorcia's experience using a ZD encoder.

Once we can reverse engineer the value of the resistor in the new repros, it looks like the best advice going forward is to do the inline amperage test described above to confirm the presence and value of the resistor since we don't know when a resistor was added to the repros but we do know that it wasn't in the original part.

For example, if they used a 150 ohm resistor so the LEDs conduct 20mA @ 5v . . .
. . . then by adjusting the LED current rating in the calculator you can figure out what would happen if you add a 220 ohm resistor. (370 ohms total -- the calc rounds to the nearest value 360 ohms)  The calc returns that size resistor with about 8.4mA.


You can go for much higher resistor values, if you want. it won't hurt anything.

For example on GreenAntz there is a power LED, a normal 3mm, 20mA rated, 2v green LED, powered by <5v, and I use a 68K current limiting resistor for that. The LED still lights and is bright enough to be easily seen, even if supply drops to 4.5v, and it only consumes a tiny ~0.04mA current. This is significant as the entire GreenAntz unit only uses about 80-90mA in total, didn't want to blow that out with a 20mA LED.

Viewed in this context, a 6.8k resistor for a volcano button LED does not seem unreasonable.

I installed the buttons in my main full size 2 player cabinet and it looked out of place so I opted for the white P1 and P2 start buttons instead. I originally used the repro's in my A1UP 12-in-1 which is Atari themed and looked really good. My A1UP's were all reverted to stock with the intention of selling them but the Deluxe is a discontinued Gen 1 so I'll keep that one and put the repro's back in with a 5v source and 220 ohm resistor.


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