Arcade Collecting > Miscellaneous Arcade Talk
Reproduction Atari Volcano Switch Voltage
Drakkorcia:
I have a couple reproduction volcano button switches from Arcadeshop It has a 6.8K resistor and has 5A 250V printed on the switch. I originally used these with my zero delays and plugged them into the 5V power slot and they worked perfectly. But now I use a 12V molex LED chain for my LED buttons. I want to know if I plug this switch into my 12V chain, will it blow the LED? Seems like it should work if all the other button LED's do.
PL1:
--- Quote from: Drakkorcia on January 23, 2022, 03:55:00 pm ---5A 250V printed on the switch.
--- End quote ---
That is the rating for the switch, not for the LED.
They are in the same physical assembly, but are not electrically connected to each other.
--- Quote from: Drakkorcia on January 23, 2022, 03:55:00 pm ---It has a 6.8K resistor
--- End quote ---
That is a much higher value than expected for 5VDC or 12VDC power.
Only application I can picture that would use that large of a resistor is if you're using 120VAC to power the LED. :lol
--- Quote from: Drakkorcia on January 23, 2022, 03:55:00 pm ---I want to know if I plug this switch into my 12V chain, will it blow the LED? Seems like it should work if all the other button LED's do.
--- End quote ---
12v will blow that LED unless you use the right size current limiting resistor.
What you don't see about the other button LEDs is that there is a current limiting resistor hidden in the LED holder.
Javeryh used these volcano switches in his build here.
--- Quote from: javeryh on December 13, 2020, 08:05:06 pm ---So anyone have any idea how to wire the volcano buttons? I got them from Arcade Shop.
--- End quote ---
You'll find lots of useful info in that thread.
- The one change is that instead of using 5v to power the LED, you plan to use 12v so you'll need a much larger current limiting resistor than the 220 ohm that he used.
- Javery's setup dropped 2v across the LED and 3v across the current limiting resistor -- 5v total.
- Your setup will need to drop 2v across the LED and 10v across the current limiting resistor -- 12v total.
Running these numbers through an LED calculator, returns a current limiting resistor value of 510 ohms, 1/4W.
- Power supply voltage = 12v
- LED voltage drop = 2v (found in Javery's thread)
- LED current rating = 20mA
- Number of LEDs = 1
https://ledcalculator.net/#p=12&v=2&c=20&n=1&o=w
- Note: You'll need a 5% (or better) tolerance resistor because 10% and 20% don't come in this value.
https://www3.nd.edu/~jott/Measurements/Sensors/Standard_Resistor_Values.pdf
If you reduce the LED current rating to 15mA, you get a 680 ohm, 1/4W resistor.
- This will be almost as bright, and should extend the life of the LED.
- The current limiting resistor will also have less wattage to dissipate (153mW vs. 204mW) so it will be cooler.
- Note: 680 ohm resistors are available in all tolerances.
Scott
Drakkorcia:
Scott,
Thank you for the detailed and thorough assistance. I just realized I have an i-pac 2 which has 5v pins on it. The only problem is I have never used header pins before so I have no idea what kind of connector I need to crimp on the + wire so I can attach it. I don't want to solder. I also assume for the ground you would just use either the P1 or P2 ground slots, right? I understand it has been recommended to put a resistor on the wire too but I hooked these buttons to 5v on my zero delay with no trouble at all. But if it is really necessary I'll give it a shot. Never installed a resistor before...
PL1:
--- Quote from: Drakkorcia on January 24, 2022, 12:16:00 pm ---The only problem is I have never used header pins before so I have no idea what kind of connector I need to crimp on the + wire so I can attach it.
--- End quote ---
They are commonly referred to as Dupont pins.
They can be a bit tricky to crimp properly, but you can avoid that by using pre-crimped wires or jumpers.
--- Quote from: Drakkorcia on January 24, 2022, 12:16:00 pm ---I don't want to solder.
--- End quote ---
Then Euro-style terminal strips are your friend. ;D
--- Quote from: Drakkorcia on January 24, 2022, 12:16:00 pm ---I also assume for the ground you would just use either the P1 or P2 ground slots, right?
--- End quote ---
Correct.
That's how Javery did it for his build here.
- He asked the same type of questions that you're asking. That's why I included the link to his thread earlier. ;)
- If you're using 5v to power the LED, use a 220 ohm resistor.
- A 1/4 W or 1/8 W resistor is more than large enough -- 1/2 W as recommended in this image is a bit of overkill.
--- Quote from: Drakkorcia on January 24, 2022, 12:16:00 pm ---I understand it has been recommended to put a resistor on the wire too but I hooked these buttons to 5v on my zero delay with no trouble at all. But if it is really necessary I'll give it a shot. Never installed a resistor before...
--- End quote ---
I'm really surprised that the LEDs didn't fry when you hooked them to 5v on your ZD.
- Maybe there is some sort of current-limiting circuit in the ZD that protected the LEDs. :dunno
You need to limit the current to around 15 to 20mA for most LEDs or they'll blow like a fuse -- that's why a current-limiting resistor is your friend.
Scott
Drakkorcia:
It would help if there was actually some documentation on these repro's. Maybe the LED on it can handle 5 volts? Maybe I just got lucky? In any case a resistor should be very cheap and could easily be soldered and shrink wrapped inline and there would be no doubt.
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