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Main => Main Forum => Topic started by: NoBonus on April 05, 2005, 04:07:28 pm

Title: Standalone LED system?
Post by: NoBonus on April 05, 2005, 04:07:28 pm
I want to add some LEDs to my control panel, but I do not want to tap into the power from my MAME pc.  I realize that standalone systems exist, but none are cheap enough for me (that I have seen).
Title: Re: Standalone LED system?
Post by: cholin on April 05, 2005, 04:16:35 pm
Ahh easy!  You CAN use an old power supply with LEDs and resistors.  Make sure you calculate the values right and whether you're doing it in series or parallel.  Also, as for the on/off switch, you wire a switch to the +5 or +12 or whatever side of your circuit.  So where you get the molex, on the red wire, you would place the switch somewhere along that line before any of your LEDs.

Edit:  Why wouldnt you just use the power on your mame system?  It's basically the same, except it saves you a PSU.
Title: Re: Standalone LED system?
Post by: NoBonus on April 05, 2005, 04:22:39 pm

Edit:
Title: Re: Standalone LED system?
Post by: cholin on April 05, 2005, 04:48:32 pm
Im not sure what you mean.  Are you saying you're building just the control panel to interface to a computer, or are you building one of those panels with a computer inside of it, so that you can just hook it up to a TV?  Good luck with it either way  ;D
Title: Re: Standalone LED system?
Post by: NoBonus on April 05, 2005, 04:52:52 pm
I am building a free-standing control panel that can be hooked up to any computer with MAME on it.
Title: Re: Standalone LED system?
Post by: johnnysmitch on April 05, 2005, 05:05:45 pm
^ a computer power supply might be kind of an overkill for just lighting up some LEDs for your panel... depending on how much lighting you have in mind, you might want to look into just battery powering it (LEDs have very low draw, even the ultrabrights), or getting a small AC adaptor or something along those lines (check out mouser.com, allelectronics.com), which would save you a bunch of space, and possibly even some wires. If you're really feeling adventurous, you could rig it up to power the lighting off the USB port, too.
Title: Re: Standalone LED system?
Post by: Trimoor on April 05, 2005, 05:08:26 pm
Don't bother with a spare PC power supply for just a few LEDs.  Use a 5-12V DC adapter, commonly called a wall wart.  They are cheap and extremely simple to use.

Or you could use batteries.  Buy a 12V rechargeable lead acid battery, and it will drive LEDs continuously for months before needing a recharge.
Title: Re: Standalone LED system?
Post by: NoBonus on April 05, 2005, 05:15:14 pm
How do I rig up a switch and leds to a battery?  Do I find a LED flashlight and rip it apart? If so, where do I get one for cheap?
Title: Re: Standalone LED system?
Post by: oldsage on April 05, 2005, 05:17:50 pm
I've been thinking about adding an extra PSU for my "interface box"... You guys make it sound horribly unneeded, but I'll keep mine because of extendability - might want to add a "shocker module" to my cab one day... :)

Back to the topic - do i need an individual resistor for each led if i power them off a PSU? I'm not that familiar with this stuff... What do you need a resistor for anyway?

(sorry if I'm hogging your thread... If this is unrelated feel free to ignore me...)
Title: Re: Standalone LED system?
Post by: tetsujin on April 05, 2005, 05:20:44 pm
Back to the topic - do i need an individual resistor for each led if i power them off a PSU? I'm not that familiar with this stuff... What do you need a resistor for anyway?

You need the resistor to prevent too much power from going to the LED.  Too much power will cause it to burn out.  You need to have one resistor per LED if they're in parallel - if they're in series, you can use just one.
Title: Re: Standalone LED system?
Post by: cholin on April 05, 2005, 06:34:22 pm
AS LONG AS THEY'RE THE SAME COLOR!  Electricity takes the easiest path.

Absolutely beautiful tutorial: http://lsdiodes.com/tutorial/

It's short and it explains everything.
Quote
How do I rig up a switch and leds to a battery?
Get a battery pack with wires first of all.  Then, wire them up the same way as you would with a PSU, red is positive, black is negative(ground).
Title: Re: Standalone LED system?
Post by: NoBonus on April 05, 2005, 07:49:20 pm
So, I guess the real question is how many 5mm Blue 5900mcd LEDs do I need to properly illuminate a transparent blue trackball?  Is there a better Blue LED choice? is 5mm overkill? Should I look for the THC3 11000mcd LEDs?
Title: Re: Standalone LED system?
Post by: cholin on April 05, 2005, 08:11:55 pm
I think that 2 regular blue ones should do the trick, especially if you buy a cheap dollar-store flashlight and use the shiny plastic reflector.
Title: Re: Standalone LED system?
Post by: Gamecab on April 05, 2005, 11:03:04 pm
I want to add some LEDs to my control panel, but I do not want to tap into the power from my MAME pc.
Title: Re: Standalone LED system?
Post by: Trimoor on April 05, 2005, 11:18:07 pm
Or you could use the 5V connection on your keyboard encoder...
Title: Re: Standalone LED system?
Post by: cholin on April 05, 2005, 11:18:49 pm
That's what I dont understand, why you wouldn't just take the 5v from the MAME machine through the keyboard socket.
Title: Re: Standalone LED system?
Post by: NoBonus on April 06, 2005, 12:06:13 am
I'm using a Keywhiz eco, where is the 5v?
Title: Re: Standalone LED system?
Post by: Tiger-Heli on April 06, 2005, 10:38:30 am
I'm using a Keywhiz eco, where is the 5v?
Lower left pin, labelled V - (when viewed with the logo up and the keyboard connector to the left)