? WAY TO USE LED'S ? WHAT DO U THINK. ?

[MrMaloo]

Here's a link to an old thread where I put LED's through my DE Star Wars Brett.

http://aussiepinball.com/index.php?topic=3478.msg52728#msg52728


For the GI I used the frosted led's . I find they spread the light more than non-frosted led's and look fantastic .

I have since done my IJ all with led's with similar results.

[beaky]

The colour enhancement that LED allows is pretty evident.. ive seen them in STNG and it does look bloody great!!

The notion of less current draw is an interesting one though. The reduced current draw is certainly not at your 240V wall socket where you pay your bills from. The power supply in pinballs is still a straight AC transformer. Its output is determined by the winding ratio between secondary and primary.
In other words, once you apply 240V across the primary winding the secondary will pump out the same power no matter what.
You do draw less current by using LED, but the transformer does not produce less current.. what is not used in the circuit is then lost in the form of heat in the windings, so you in fact cause your transformer to run warmer.

We find this all the time in the neon industry... the transformers should be loaded at 80% of their 30mA output limit. Under this amount and you run your load harder causing a loss of time that the neon will run as the electrode shells run warm, the transformer runs hot also. Anything over this 80% limit and you attempt to draw too much current and run your transformer hard causing loss of life in that.
Straight AC transformers are designed to work within a load limit... LED in your machine will not save you any $$$'s - you have to change your transformer to do that. It is also feasible that if using ALL led you will burn your transformer out... but this is theorising and i cannot of course prove this.

Now... were your power supply a switch mode type, then yes.. it churns out what is required dependant on load... but your AC winding transformer will always convert X to Y no matter what you do, unless you change the winding ratios

the comment about the heat may be true with neon transformers (high voltage secondary winding) but this is not the case with a transformer that has a secondary winding lower than its primary winding.

the later transformer will draw x milliamps when there is no load but the more you load the secondary winding the more current the primary windings will draw from the 240v ac supply.
I just set up a transformer infront of 2 people (1 from this forum) with an amp meter in series with the primary side. With no load the primary side was drawing 250ma, as soon as i put a 50watt lamp on the secondary side the current draw on the primary side rose sharply to 750ma then dropped back to 640ma. as soon as i disconnected the 50watt lamp from the secondary side the current on the primary dropped back down to 250ma.

the transformer that was used for the test had a secondary winding rated at 24Volts, and the maximum load it can take is on the scondary is 27 amp (around 648 watts)

with a wire wound transformer (that has a lower secondary voltage than the primary) the more you draw on the secondary the more you draw on the primary.
The more current you draw the hotter the transformer will run.

My old boss at hawko will back me up on this. Hawko manufactures there own wire wound transformers. They buy the E & I pieces, copper wire, & spools. Then they start by winding the thin primary winding, next the thicker secondary winding is wound on (the higher the va the thicker the secondary winding). the E & I pieces are then put on the spool, then it is dipped in isonol. it is then baked in an oven for about 6 hours to dry the isonol. And last, the terminal blocks and thermal circuit breaker is fitted to the transformer.


if need be i can video the test and up load to youtube

[beaky]

LEDs are no good for GI - the main reason is that they are too directional and for GI you need a more generous spread of light.

This criticism and that the leds are too white is often made.  I wonder exactly which leds people have used - they all seem to be lumped under the same de******ion as "leds", but there is quite a variety.  I see that cointaker have some 170° warm white ones that I've wondered how they'd go behind a BG or big bit of plastic.  I like the idea of reducing heat on BG.

I wonder if a led controller to turn them down a bit might help - not that easy to do as these normally control leds in series strings, whereas pins use parallel strings for GI.  I also wonder if a sheet of diffuser between leds and backglass might help, maybe something as simple as tracing paper.  I've also heard, maybe on this site, of people sanding the led surface to difuse it some more.

It is possable to make a unit to adjust the brightness of the leds, I wonder how many people would be interested in buying them if someone made a "plug and Play" type of dimmer with a trimpot you can turn to change the brightness?

[Caveoftreasures]

So what you are trying to say Andrew, is that a pinball machine that is plugged into a wall, with 100 normal bulbs, uses alot more power than a machine using only LED's.

Therefore, if u were to put the machine in a test mode, say with all bulbs flashing, you could measure the consumption.

Then, you could measure the same draw, with the same machine that has only LED's and work out the difference.

So led's will save on power, but overall, only power usage on the lighting circuit which is only a part of the overall power consumption.

** We might kit out 1 x star trek next gen with only LED's, then kit out my other STNG with the std bulbs, and measure the difference. !

[Extra Ball]

LEDs are no good for GI - the main reason is that they are too directional and for GI you need a more generous spread of light.

This criticism and that the leds are too white is often made.  I wonder exactly which leds people have used - they all seem to be lumped under the same de******ion as "leds", but there is quite a variety.  I see that cointaker have some 170° warm white ones that I've wondered how they'd go behind a BG or big bit of plastic.  I like the idea of reducing heat on BG.

I wonder if a led controller to turn them down a bit might help - not that easy to do as these normally control leds in series strings, whereas pins use parallel strings for GI.  I also wonder if a sheet of diffuser between leds and backglass might help, maybe something as simple as tracing paper.  I've also heard, maybe on this site, of people sanding the led surface to difuse it some more.

I wonder how many people would be interested in buying them if someone made a "plug and Play" type of dimmer with a trimpot you can turn to change the brightness?

me for starters

[beaky]

So what you are trying to say Andrew, is that a pinball machine that is plugged into a wall, with 100 normal bulbs, uses alot more power than a machine using only LED's.

Therefore, if u were to put the machine in a test mode, say with all bulbs flashing, you could measure the consumption.

Then, you could measure the same draw, with the same machine that has only LED's and work out the difference.

So led's will save on power, but overall, only power usage on the lighting circuit which is only a part of the overall power consumption.

** We might kit out 1 x star trek next gen with only LED's, then kit out my other STNG with the std bulbs, and measure the difference. !

correct

[FirePower]

It is possable to make a unit to adjust the brightness of the leds, I wonder how many people would be interested in buying them if someone made a "plug and Play" type of dimmer with a trimpot you can turn to change the brightness?

It is posible to make led controllers and they do exist. Buckpuck are good examples but there are heaps of cheaper alternatives - look at Jaycar for a few and Deal Extreme for many examples. BUT you would need modifications to work in a pin.  Led brightness is regulated by current and that's how theses controllers work. To get them all the same current you want to pass the same current thru each led - this is done by arranging them in series.  Pins arrange GI in parallel, so you'd have to rejig the wiring, could be done - but I'm not sure it would be worth the effort unless you were rebuilding the pin.  If  you did you could get some interesting effects as some of these controllers will flash, dim etc and could be controlled programatically by the pin or features of teh gameplay. A sort of modern take on Blackout but with more bells and whistles.

For a variety of other (fairly boring to most!) reasons, the Cointaker or Ablaze leds would not be the best to use in this setuip either, so you want to look at making your own bases etc - it all starts to look a bit like too much work.

[beaky]

you only need to drop the voltage, when you drop the voltage the current will also drop.
you will need to make it so the voltage is adjustable from 6.3volts down to around 4.0 volts.

again i made the same type of variable power supply when i was working at hawko. the leds that are in there bud lighting works on 12volts with 1 led, or 2 leds in each fitting wired in series.
the led pcb would then plug in to a wedge socket, the wedge sockets were wired in parallel. The reason why they ran on 12 volts is because of the cable lengths.

any way some customers where complaining that the leds where to bright in some applications so I designed a regulated power supply with a trimpot (that controlled the voltage regulator) to dim the leds.

In saying that some led power supplies regulate the current as they are made to run x amount of leds as fire power suggested.

I still have a schematic diagram for the variable led power supply.

the led pcb for the wedge socket is pictured below, the pin configuration on the sockets used for these leds where different than the pinball 555 sockets, if you plug the pcb in the picture below onto a pinball socket it will just short the socket out. (the one pictured had a couple of wires soldered on to it at one stage, hence the untidy solder at the bottom)

[FirePower]

Hi Beaky, I read with interest your posts on electronics stuff and find them interesting and informative, but to be frank, and I mean absolutely no offence and cheerfully add that you should feel free to ignore me, I reckon your led techniques and understanding are far from current and good practise.

The Vf of a led is a function of the junction material, they are not a linear device as you are presenting them. Most have a Vf of about 2.3 volts, the technique you've described works in limited cases with small numbers of leds (in each group) between the supply voltages and where the sum of the led Vfs (in each group) roughly matches the supply output voltage.

(This is also the reason the Cointaker and Ablaze leds can be used in parallel wired strings - as everyone who buys them uses them - they have an inbuilt resistor that acts as a current limiter, or a primitive current regulator if you like, in each led. This is also the poor feature that I alluded to in my earlier post)

Good practice drives leds in series and regulates current to vary brightness. A pretty fair summary can be found here http://www.ledsmagazine.com/features/4/8/1

A string of leds like the GI in a pin with about 40 to 50 driven all in parallel (with no current limit resister as described above) will suffer variations in brightness amongst individual leds due to variations in junction temperatures and the thermal runaway that will result. This would be made worse if you tried to use different coloured ones. I strongly suspect driving it this way will lead to failures of those that operate higher up on the Vf v If curve. This will lead to rapid increase in junction temp, lower junction resistance,  higher current flow and ultimately failure.

One technique people use is to place several strings of series leds in parallel to even out these differences - this is how I would go about it if I were trying to control strings of GI leds. Take a feed of about 25V, loose a few volts headroom for the regulator and then arrange, say, 4 or 5 parallel string each with ten series leds in them.

Anyway. I'm happy for us to disagree and we can each continue to drive our leds in ways that we like, each of us secure in the knowledge that the other is wrong! Good luck to you and your leds.

[Extra Ball]

may as well put a pic up of my homemades:



I didnt take photos, but I was able to squeeze 2 LEDs into a socket like that. They work absolutely fine, have for 6 months so far. You cant see it, but a resistor is in there.

[beaky]

Hi Beaky, I read with interest your posts on electronics stuff and find them interesting and informative, but to be frank, and I mean absolutely no offence and cheerfully add that you should feel free to ignore me, I reckon your led techniques and understanding are far from current and good practise.

The Vf of a led is a function of the junction material, they are not a linear device as you are presenting them. Most have a Vf of about 2.3 volts, the technique you've described works in limited cases with small numbers of leds (in each group) between the supply voltages and where the sum of the led Vfs (in each group) roughly matches the supply output voltage.

(This is also the reason the Cointaker and Ablaze leds can be used in parallel wired strings - as everyone who buys them uses them - they have an inbuilt resistor that acts as a current limiter, or a primitive current regulator if you like, in each led. This is also the poor feature that I alluded to in my earlier post)

Good practice drives leds in series and regulates current to vary brightness. A pretty fair summary can be found here http://www.ledsmagazine.com/features/4/8/1

A string of leds like the GI in a pin with about 40 to 50 driven all in parallel (with no current limit resister as described above) will suffer variations in brightness amongst individual leds due to variations in junction temperatures and the thermal runaway that will result. This would be made worse if you tried to use different coloured ones. I strongly suspect driving it this way will lead to failures of those that operate higher up on the Vf v If curve. This will lead to rapid increase in junction temp, lower junction resistance,  higher current flow and ultimately failure.

One technique people use is to place several strings of series leds in parallel to even out these differences - this is how I would go about it if I were trying to control strings of GI leds. Take a feed of about 25V, loose a few volts headroom for the regulator and then arrange, say, 4 or 5 parallel string each with ten series leds in them.

Anyway. I'm happy for us to disagree and we can each continue to drive our leds in ways that we like, each of us secure in the knowledge that the other is wrong! Good luck to you and your leds.

no probs and please take no offence to my statements.
all of the leds that i have run on a string has their own resisitor on each pcb (if you look at the picture you will see 2 small resistors)
the reason why we ran them in paralllel is the machine that makes the strings was used originaly to make pixie light strings with incandecent lamps.

i agree that an led is not a linear device.
the led systems i made for the company i worked for where made between 2000 and 2005, the majority of the systems i made are still in service today.

some of the circuit boards i made for light fitings (pool lights, garden lights and various other low voltage light fittings) had up to 100 leds in them, in that instance the pcb had the leds wired in series and then wired in parallel, depending on the colour we would have 3 or 4 leds in series. (blue and white 3 in series and all other colours 4 in series).

so as far as using them in a pinball no one i know has rewired there G.I circuits in series.
and with my past experiences with leds they can be used in parallel with a resistors on each led and then be dimmed via dropping the voltage with out shortening the life of the led.

when you drop the voltage the current also will decrease.

If you have more than one set of leds running in series off a power supply and you dont use a resistor to current limit each set of leds and use a current limiting power supply you can run into some serious problems if 1 of the series go out.
I.E. if i had a power supply running 3 sets of leds that are running in series and each series of leds take 30ma, and you have your current limiting power supply set at 90ma (3 sets of leds @ 30ma = 90ma) and one of the series go out then you will be running 90ma into 2 sets of leds that only need 60ma, the 2 remaining sets of leds wont take long to die.

another problem you would have in the same scenario is 1 set of leds will have a lower foward voltage than the other 2 sets, it is very rare to have a identical foward drop in 2 leds.

in my opinion using a current limiting power supply to run more than 1 set of leds in series is not practical.

B.T.W. the power supply that i use to drive my leds at work and at home is a switch mode power supply. the way it regulates its output is via pulse width modulation so the power supply gives out very little heat.

again no offence

here is the desri p tion of the I.C. that is used in my power supplies:

The MAX724/MAX726 are monolithic, bipolar, pulsewidth
modulation (PWM), switch-mode DC-DC regulators
optimized for step-down applications. The
MAX724 is rated at 5A, and the MAX726 at 2A. Few
external components are needed for standard operation
because the power switch, oscillator, and control
circuitry are all on-chip. Employing a classic buck
topology, these regulators perform high-current stepdown
functions, but can also be configured as inverters,
negative boost converters, or flyback converters.
These regulators have excellent dynamic and transient
response characteristics, while featuring cycle-by-cycle
current limiting to protect against overcurrent faults and
short-circuit output faults. The MAX724/MAX726 also
have a wide 8V to 40V input range in the buck stepdown
configuration. In inverting and boost configurations,
the input can be as low as 5V.
The MAX724/MAX726 are available in a 5-pin TO-220
package. The devices have a preset 100kHz oscillator
frequency and a preset current limit of 6.5A (MAX724)
or 2.6A (MAX726).

And here is the link that has a basic power supply and the data sheet
http://pdf1.alldatasheet.com/datasheet-pdf/view/73748/MAXIM/MAX724CCK.html

[Caveoftreasures]

Well, I have worked something out, 

IF WE CAN GET BEAKY AND FIREPOWER ON ONE OF THOSE TV SHOWS AND SAY
"YOU HAVE 4 HRS TO MAKE AN ELECTRICAL SOMETHING, AND HERE ARE A LIMITED SET OF PARTS, AND SOME BASIC TOOLS, GO FOR IT, TIME STARTS NOW, WORK TOGETHER"

I am sure you two electronic bloody wizards would probably end up making a friggin satellite that cooks toast and flashes plus a whole extra whack of excellent stuff cause you blokes have lost me with technical nobel prize Einstein stuff.

But at least we know you guys are very cluey indeed. If i ever get ship wrecked, I want you two to build me the radio so we can get saved (only if the local native women arent worth staying for) 

Back on topic, lets see more photos of pinballs with LED's please anyone.

 

[beaky]

may as well put a pic up of my homemades:



I didnt take photos, but I was able to squeeze 2 LEDs into a socket like that. They work absolutely fine, have for 6 months so far. You cant see it, but a resistor is in there.

what happend to the photo you had up before?
 
any way that led in the my picture would be more suited to use in a flasher. the manufacture specify that you run it at 50ma

[Extra Ball]

may as well put a pic up of my homemades:



I didnt take photos, but I was able to squeeze 2 LEDs into a socket like that. They work absolutely fine, have for 6 months so far. You cant see it, but a resistor is in there.

what happend to the photo you had up before?
 
any way that led in the my picture would be more suited to use in a flasher. the manufacture specify that you run it at 50ma

What photo Beaky? Did I ever post version 1 of my homemades? That one wont be posted again lol

[shootar]

My T2 fully LED'ed. Blue frosted GI under return lanes and red under the slings.

came up a treat - way better than new. In the dark its a light show!