Yet another LED question.

[shorts in montana]

I am employed at a bowling center. The pinsetters have two lights that indicate the first or second ball status of the machine. One light on = first ball & two lights on = second ball. The lights show through an opaque white panel at the end of the lane. The pinsetter powers these lights, which are 1252s, with 30VAC. Due to the constant on-off cycling and viabration we lose over 150 bulbs during a season. As a test, I rigged a circular group of seven 800mcd wide angle red LEDs, used 220ohm limiters on each and powered them with a 6 volt battery. I mounted them on the front of the masking units @ the appearance was great. My problem is that while I stumbled along and got the battery thing going, I dont know what to do when it comes to powering the LED group with the 30VAC from the pinsetter. Do I half-wave or full-wave rectify the AC? What wattage resistors would be required for the LEDs? Any help for this rookie from the great pool of knowledge would be greatly appreciated.

[dyarker]

Have you seen the LED nightlight article in August's N & V?<p>Use a full wave bridge rectifier. 30VAC is peak:
30VACrms * 1.414 = 42V peak<p>Put the seven LEDs in series. They will have:
~2V * 7 = 14V<p>The resistor, ahead of the rectifier:
(42V - 14V) / 0.02A = 1400 Ohms, use 1200 Ohms
(42V - 14V) * 0.02A = 0.56W, use 1 Watt<p>Do NOT put a big filter cap after the rectifier. Then you'd need a different resistor. 0.1uF across the LEDs should flatten any spikes.<p>Cheers,

[dacflyer]

what color leds are you using ?? if interested i got lots of red / yellow / green ones...more green that anything else...meggabright!<p>[email protected]

[dacflyer]

oh the horror... i used to be a bowling lane tech....GOD i hated it.. i lasted about a year then couldn't take it no more...the machines were too worn out..owner didn't do nothing but just try to keep them patched up..i begged for help...but i was only tech they had.one night i had enough and walked out on a 52 lane bowling league night...
needless to say...many were mad after i left..
i had a awsome idea for almost eleminating ball stuck calls...cause of the ball return belt had gotten a little oily...they had some sort of block there..polymerebased i think...i had let this rub on the belt and i wouldn't get no ball stuck call all night....but owner complained to me that some patrons were complaining that their ball would have a scuff mark on it...which readily rubbed off...but,,,he said i had to stop...so i did....then later on left...
worst is when the pins pile up on top of the loader...Grrrrrrrr

[shorts in montana]

DALE Y. Thank you very much for the reply. I've been doing 18/7's for the last two months and my reading has suffered accordingly so i did not see the article you pointed out. I have now. Tnks.
dacflyer. I intend to use red LEDs for this project and have already ordered from Jameco. Thanks for the offer. I think I recognize you from the BOWL TECH forum. I am in the fortunate position of working for a proprieter that gives me pretty much free reign in the expenditure of funds. My newest pinsetter was manufactured in 63 so I know what you had to put up with.

[dacflyer]

naaaaa i never was in bowl tech....but good luck anyway

[shorts in montana]

Dale Y. What type of cap should I use for the spike catcher? Thanks.

[dyarker]

50V or 63V rating, 100V okay. EWAG 0.047uF to 0.1uF. Ceramic, paper, mylar or poly.

[Enzo]

Hey something else to consider. Are these lights just switched by a relay and that puts the 30VAC across them? In any case, you might think about what they do in show biz - the pre-heat.<p>Stage lighting uses very expensive lamps (bulbs)and you don't want them failing all the time because it is inconvenient to change them. So rather than turn them completely off, when they are in the "off" mode, they are really still powered, but not enough to light them up. SO they are warm all the time. When the full power comes on there is no thermal shock.<p>If there is a relay, put a suitable resistor across the contacts. The resistor will keep the filaments warm, and the relay when it comes on will short across the relay and power the lamp as usual. If it is triac switched, it still ought to work, put a resistor across the main terminals of the triac. I bet 40 year old stuf didn't use triacs for the lights.<p>You would have to experiment a bit to get the right resistance and power rating. You want the resistance low enough that the filament is just about to glow, no lower. a dim redness indicating heat is fine. The bowlers will never see that.<p>Then from the resistance and the voltage across it - or the current through it -you can determine the wattage resistor you need. I would use a resistor rated for about twice what the circuit needs.<p>The beauty of this is there is no extra stuff to wire in except the resistor in each spot.<p>Just a thought. Try it on one lane.

[shorts in montana]

Enzo. Thanks for the input. We run a smoke & light show at the center on weekends, with around fourteen different lighting effect devices in use, so I'm well aware of what you're talking about in respect to the expense of the bulbs. However, I dont think I can use your excellent idea with the ball indicators. We use an automatic scoring system & the output from the 1-2 lights are tied into the computer through opto-isolaters. I'm afraid that any useful preheat power would probably be more than enough to activate them. Thanks again for your effort to resolve my problem.