(Topic ID: 68357)

I need 12v for an led strip on my F-14


By Double_D

6 years ago



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  • 23 posts
  • 15 Pinsiders participating
  • Latest reply 1 year ago by indypinhead
  • Topic is favorited by 7 Pinsiders

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#1 6 years ago

I do not have much experience with the electronics of a pinball machine and I have a question.
I want to hook up a 12v dc led strip in my F-14 game. I'm not sure exactly where I'm going to place it since there is not a lip at the top of the pf so I'm still open to different points where I can find 12v dc. I did find a pin on the psb connector 3j6 that has a 12v dc unregulated pin. Pin 2 and 6. Would this work for what I need or is there a better place to get the 12v from? I'm trying to light up the upper pf area. I did find that an 12v unregulated circuit is not exactly 12v but usually higher. Also what is the difference between +/- 12v? I do appreciate the help, thanks.

#2 6 years ago

You do NOT want to use an unregulated power source. If there's not a regulated 12V DC option in the game, a lot of users will simply drop an ATX Switching Power supply (used in arcades, PCs, etc...) and pull the 12V from there. The power supply can either be plugged into the extra outlet in your game, or have the cable fed through the rear hole to a wall socket.

#3 6 years ago
Quoted from wxforecaster:

You do NOT want to use an unregulated power source. If there's not a regulated 12V DC option in the game, a lot of users will simply drop an ATX Switching Power supply (used in arcades, PCs, etc...) and pull the 12V from there. The power supply can either be plugged into the extra outlet in your game, or have the cable fed through the rear hole to a wall socket.

Thanks for the info. I feel alot better using a power supply than poking wires into connectors hoping it works. Thanks wxforecaster.

#4 6 years ago

On the power supply board connector 3J6 pins 3 and 6 have +12 volts on them. Pins 1 and 11 through 15 are ground.

Granted this is +12 volts unregulated, but for an LED strip it's close enough. People use LED strips in cars and the voltage can go as high as 14.5 volts. I think you'd be ok picking up your power at 3J6.

#5 6 years ago

I'd be interested how this comes out...follow up with us Double D...

#6 6 years ago

Ken,

I wouldn't do it, not because the LEDs will blow, but because the tolerance in voltage on an unregulated circuit is so much that you will very likely see oscillations in brightness. For a $5 or $10 power supply, I would personally keep the LED strip separate. Like you said, throwing it on 3J6 likely won't harm anything, but the results may or may not be desirable.

#7 6 years ago

Use the 3j6 as ken said or 12v unreg. You will be fine. It is easier to come off the post imoo.

#8 6 years ago

I've used that unreg to drive 12vdc leds on a System 11 a few times with no ill effects. Besides, its easier to do and if it does not look right, THEN add in the regulated PS.

#9 6 years ago

If you check http://www.dkpinball.com/ I have power tap products for just this thing.

I do have a Tap product that will fit F-14, i just don't have it up on the web site yet. Check out the Data East power tap and the online installation instructions. The data east is very similar to the system 11. You can see it here: http://www.dkpinball.com/DKWP/?page_id=601

It gives you two fused sources. One for 12v and one for 5v. If your mod shorts out or if you overload it, the fuse will blow on the tap rather than on your game.

And, you're fine with the 12v unregulated for LED strips.

PM me if you're interested and if you have any questions. I have a lot of different solutions for power distribution and control.

#10 6 years ago

Wow..Lots of great advice. Thanks everyone. Since I could do it today, I went ahead and put it in pin 3-12v dc and 1-ground. Works great and an easy fix. I'll let you know if it continues to work with no problems. Thanks Ken

dk - I like the look of the power taps and down the road will try this in at least one of my machines, probably the BSD.
I like the security of fused sources. Thanks

#11 6 years ago
Quoted from Double_D:

Wow..Lots of great advice. Thanks everyone. Since I could do it today, I went ahead and put it in pin 3-12v dc and 1-ground. Works great and an easy fix. I'll let you know if it continues to work with no problems. Thanks Ken

Lets see some photos then!

#12 6 years ago
Quoted from practicalsteve:

Lets see some photos then!

Pics please.

#13 6 years ago

I solder male connectors on the coin door circuit board sometimes to pick up 12v. I also make use of the power supply at the transformer. I stay away from the backbox wires. I have had no issues.

#14 6 years ago
Quoted from wxforecaster:

Ken,
I wouldn't do it, not because the LEDs will blow, but because the tolerance in voltage on an unregulated circuit is so much that you will very likely see oscillations in brightness. For a $5 or $10 power supply, I would personally keep the LED strip separate. Like you said, throwing it on 3J6 likely won't harm anything, but the results may or may not be desirable.

No offense intended as I see this time and time again, but just wanted to say that LED lamps are either on or off - there is no change in brightness due to input voltage level. If the input voltage drops below the cut off threshold, the LED simply turns off. Adjusting the input voltage will not cause a change in brightness

Brightness control of a LED is a relative term.

LED "brightness" can [u]only[/u] be controlled by pulse width modulation. It is a perceived intensity change that the human eye see due to it's limitations. By adjusting the pulse width or how long power is supplied vs off to the LED determines it's "brightness" (we are talking msec here). There is a point where the duty cycle (the time on vs the time off) will produce a flicker.

#15 6 years ago

Are you going to post a pic of the finished game ?

#16 6 years ago
Quoted from pinballbrat:

Are you going to post a pic of the finished game ?

Not ready for pics yet. As soon as I figure where I'm going to locate the strip for the best result of lighting the upper pf. Now that I have the voltage located I might end up with spotlights instead. Thanks again.

#17 6 years ago
Quoted from LongJohns:

No offense intended as I see this time and time again, but just wanted to say that LED lamps are either on or off - there is no change in brightness due to input voltage level. If the input voltage drops below the cut off threshold, the LED simply turns off.

You're right to suggest that PWM should be used to vary the brightness of LED's, but altering the input voltage does alter the brightness. They aren't just on or off. The brightness is driven by the current and with a fixed resistor, the current will go up or down based on the input voltage. It doesn't do it linearly, and you can get outside of efficient ranges quickly, so altering the current isn't the preferred way to control LED brightness.

If you put two of the same LED/Resistor combinations next to each other and feed one 4v and the other one 12v, you will definitely see a brightness difference. Real life example: This past week I was fitting cheapo 555 LED's to clear flipper buttons to make an inexpensive lit flipper button. I plugged it in and was really happy with how bright they were. Then I saw the smoke. I had connected the 6.3v pinball LED to 12v. Changing to 5v made the bulb significantly less bright. I swapped out new bulbs because damaged LEDs will appear less bright. It was still significantly less bright.

With 12v strips though, you're not going to see much difference between 11 volts and 13 volts, that's why I said that 12v LED strips on an unregulated 12v supply are fine.

#18 6 years ago
Quoted from LongJohns:

No offense intended as I see this time and time again, but just wanted to say that LED lamps are either on or off - there is no change in brightness due to input voltage level. If the input voltage drops below the cut off threshold, the LED simply turns off. Adjusting the input voltage will not cause a change in brightness
Brightness control of a LED is a relative term.
LED "brightness" can [u]only[/u] be controlled by pulse width modulation. It is a perceived intensity change that the human eye see due to it's limitations. By adjusting the pulse width or how long power is supplied vs off to the LED determines it's "brightness" (we are talking msec here). There is a point where the duty cycle (the time on vs the time off) will produce a flicker.

No offense taken, and in my mind I now realize that what I posted doesn't make sense at face value. However, I had read recently that you could put in a variable resistor (pot.) in line and alter the brightness by modifiying the resistance. It would seem to reason that the intended purpose of a resistor is to limit the forward voltage down to that required by the semiconductor material in the LED. There is obviously some wiggle room in here and exceeding that forward voltage by some fixed amount would blow the LED?

Reading dkpinball's response, I'm now confused even more so. Time to experiment. There are two key questions here. Given forward voltage XXX of an LED, can the brightness be altered by means other than PWM? Secondly, what do you have to exceed XXX by to blow up the LED. In otherwords, if you have a super blue LED with a forward voltage of 3.2V and apply 12V to it, bad things are going to happen.

#19 6 years ago
Quoted from wxforecaster:

In otherwords, if you have a super blue LED with a forward voltage of 3.2V and apply 12V to it, bad things are going to happen.

Not necessarily. The short answer is that it's just not that simple. We're used to the experiment where we take an incandescent bulb and we alter the voltage and the light bulb changes brightness.

I know how the math all works but I'm still working on knowing enough about this to teach it. The LED is rated with a forward voltage of 3.3v. Any excess voltage rolls right on through. Resistors don't resist voltage, they resist current. If you had no resistor on the circuit and you fed it 5v, then 1.7v (5 - 3.3) would flow on through and with 0 resistance you would be forcing 1.7 amps through an LED that has a max rating of 30ma per the data sheet. (https://www.sparkfun.com/datasheets/Components/YSL-R542B5C-A11.pdf)

What you need to do is to put a resistor in series with the LED that will limit the current to an acceptable level for the LED. 20ma is really common for a lot of LEDs as the highest brightness with the longest life.

To get the circuit limited to 20ma you need to do this math:

(Source Voltage - Forward voltage) / .02 = Resistor Rating in Ohms.

5v - 3.3v / .02 = 85 ohm resistor.

1.7v * .02amps = .034 watts. So you could get away with a resistor rated at 1/8 watt.

I had a project that required an LED to go on when a 48v circuit was live. The LED had a forward voltage of 2.2v and of course an ideal current of 20ma.

48 - 2.2 / .02 = 2290 ohms (a 2.2k resistor was close enough).

However, 45.8v * .02 amps = .916 watts. So I needed a resistor rated at 1 watt in order to dissipate the heat.

The Blue LED shows a max current of 30ma. So you could squeeze a little more brightness out of it but the lifespan would diminish. Or you could get less brightness by allowing only 10ma through the LED.

It's just not practical to alter the resistance dynamically. You would need a crazy potentiometer that wasn't linear and had a weird lower range.

Using PWM is the preferred way because you're keeping the LED's balanced electronically but even PWM isn't completely linear where brightness is concerned. There are a lot of arduino threads on PWM curves for achieving an affect that is as close to linear as possible.

1 year later
#20 5 years ago

I will post a word of warning. I was doing this mo hooked up two of the grounds to 89 ground lugs and the 12v to an 89 lug. I hooked the 3rd ground to a 1251 ground and.... .chaos ensued. Just now cleaning that up. Not sure how much damamage but....so word to the wise. Stick to one volt type!!!

3 years later
#21 1 year ago
Quoted from KenLayton:

On the power supply board connector 3J6 pins 3 and 6 have +12 volts on them. Pins 1 and 11 through 15 are ground.

Thanks for this info! Used it to put some under cabinet lights on my Whirlwind yesterday. Total cost, $14.

IMG_20180531_224800~2 (resized).jpg
#22 1 year ago
Quoted from swilson143:

Thanks for this info! Used it to put some under cabinet lights on my Whirlwind yesterday. Total cost, $14.

See, that would just illuminate my crappy floor and show off the dirt. But, yes - I also tapped the games unreg +12VDC for flipper button LEDs. For small mods that don't draw a lot of current, usually you can find a source on the game to use. For big mods, best off installing an auxillary supply.

#23 1 year ago

On the power supply board connector 3J6 pins 3 and 6 have +12 volts on them. Pins 1 and 11 through 15 are ground.

Ken, Would this work on a DE Simpsons? I purchased a Laseriffic topper that is designed to be used on a TSPP.

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