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Wiring Atari volcano buttons in series?

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maraxle:

Hi.  I'm trying to get 4 Atari volcano (cone) buttons to be always lit on my control panel.  Can I wire them in series to either the +5V on a KeyWiz or straight to the PC power supply?

RayB:

I think so, but you'd need some resistors.
Search this board for "Atari lit buttons" or "Atari volcano button" and maybe the word Resistor too.


NoOne=NBA=:

They will need to be in parallel, or they won't get 5v.
If you wire them in series, they will only get 1.25v each.

Think of it like cookies.
If you pass one cookie down the line to four people, everyone only gets 1/4 of a cookie.
If you pass out FOUR cookies to start with, everyone gets a full cookie.

I'm not sure on the resistor part though.
They may have one in the case, but I'd check the specs somewhere before you hook it up.

Witchboard:

From what I've read doing my own searches you'll need 330R ohm resistors on your +5V line.  I think some body mentioned the switches actually say "Max +-2V" on them.  Of course I would do my own searches to verify this if I were you.  ;D  Let me know if my findings are the same as yours.

rdagger:

You could run them in series, but you would need a power supply greater than 5 volts.
First you need to determine the LED voltage which I believe is usually about 1.7 volts for a red (not a super bright) LED.  Next you need a power supply that can supply well above the total voltage used by all the LED's.  You don't want the total LED voltage to exceed 80% of the supply voltage.  If you used a 12 volt power supply and assume 1.7 volts & 15 mA per LED then you would use a 360 Ohm resistor.
Formula:  
(Supply Volts - Total LED Volts)/Current
(12-6.8)/.015 = 347
Then find the next standard resistor value above 347 which is 360.

Here's an online LED Series Resistance Calculator:
http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm

If you have to run them off 5 volts than you could run them in parallel.  It is recommended to use a separate resistor for each LED.  You also need to make sure your KeyWiz can provide enough current; otherwise you could damage it.

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