Miniscan LED conversion

[musht]

The LED is actually made up from two strings of six LEDs, so while the LED as a whole needs around 42V I only need to supply two 20-ish volt supplies. I've done it this way because LED drivers are more readily available for 24V supplies than 42V supplies.

 

Inspirational, quality design and build :-)

 

Sure you know but for others, LED drivers come in 2 flavours, constant voltage, supply voltage = LED voltage, used for things like LED tape then constant current, supply voltage > LED voltage usually used for big LEDs, where the voltage is settled to maintain a current through the LED(s).

 

The 700mA used by the LEDEngin device is common for 3W LEDs.

[gyro_gearloose]

I've turned the fan around so that it is pushing air directly over the heatsink rather than relying on the airflow through the unit to cool the LED. I'm not worried at all about the motors heating themselves up as the greatest source of heat in the original Miniscan was the HMI lamp. The lamp alone puts out so much heat that it gets the entire metal body of the unit quite warm, and this in turn gently cooks the stepper motors.

 

Heres a pic showing the LED and heatsink mounted in the Miniscan. The big silver box next to the LED is the power supply.

 

http://i157.photobucket.com/albums/t41/gyro_gearloose/ledcloseup.jpg

 

If anyone is interested in converting their Miniscans let me know. I can supply the plastic and metal parts, and put together a guide on how to do it yourself. You would then need to supply the LED, LED drivers, heatsink, and power supply. You would also need to wire up the LED. This might be a bit tricky as it is impossible to solder anything to the LEDs metal clad PCB with a soldering iron. I ended up using conductive epoxy, which is quite expensive and time consuming to use. Because of this I could wire up the LED for you if you wanted. Anyway, let me know if any of you are interested.

[Stuart91]

Presumably without the HMI lamp there is no UV present, so it would be safe to remove the pesky interlock switch?

 

(I've found they can become temperamental, especially on older units that have been bashed around)

[ladyjayne]

I am very impressed with your work but have a quick question. How is the dimmer/shutter/strobe now controlled IE mechanically or electronically and if mechanically is there a way of switching the LED source on and off via DMX?

[Jamtastic3]

LadyJane, I'm guessing that the shutters still control dimming attributes. The Miniscan HPE doesn't have a lamp control function. Although this has led me to a similar question....

 

When you power up the Miniscan (cover on) does the LED come on straight away (like how the lamp used to strike straight away)?

[timsabre]

You would also need to wire up the LED. This might be a bit tricky as it is impossible to solder anything to the LEDs metal clad PCB with a soldering iron. I ended up using conductive epoxy, which is quite expensive and time consuming to use.

 

You can solder to metal clad LED boards like that, I do it regularly. It's just a case of having a chunky enough soldering iron to transfer the heat. I've got a 45W weller with a big chunky tip and it does it no problem. However if I fit a narrow tip to the same iron, it won't do it.

 

Obviously (I hope) you should solder the wires on before you put it on the heatsink, otherwise you really will have problems.

[norty303]

Very nice! ;)

[pjb304]

I agree with timsabre having soldered about 230 of these, which although aren't quite as chunky as the LEDs in question certainly can absorb some heat with a powerful iron and a chunky tip it's perfectly possible. Just remember once soldered they take a while to cool down :(

[gyro_gearloose]

I ended up using conductive epoxy as I was wary of cooking the LED if I tried to solder it by hand. I only have a 25W iron and it couldn't heat the LED fast enough for the solder to melt! To be honest the epoxy wasn't particularly easy to use either. It takes 24 hours to set, and even then I had to keep it above 25 degrees or it wouldn't have set at all. Not an easy task in the middle of winter. In the end I pointed a pair of birdies at the LED to keep it warm. Once it had set I then encapsulated the conductive epoxy in regular epoxy to give it some strength as it would have been too brittle without it.

 

As for how the LED is powered, I simply wired the LEDs power supply so that it comes on as soon as the unit is switched on. The dimming is mechanical using the original shutters, and the lamp stays constantly at full. However the drivers I am using have the option to attach a switch so I could fit some microswitches that are activated when the shutters are closed. This would turn the LED off when the shutters are closed and help reduce power consumption still further. There wouldn't be any problem with doing this as LEDs turn on and off instantly without the 5-10 minutes warm-up time that discharge lamps need.

 

I removed the interlock as the plate it is attached to gets in the way of the heatsink. I don't need it anyway as there is now no need to open the hatch. The thumb bolt can be replaced with a regular bolt to prevent people from gaining access to any live parts.

[Jamtastic3]

So if you were to use a brighter LED source, what power of LED could you use in relation to the simplicity of your set up? (OK it's not exactly simple, but seems very straight forward rather than extremely complex). Would you need more or larger equipment?

 

It would be good to see if you could fit a brighter LED like 90w, etc. That would really get heads turning....

[gyro_gearloose]

It would be good to see if you could fit a brighter LED like 90w, etc. That would really get heads turning....

 

Fitting the 90W LED would be straight forward enough, but what would really get heads turning would be the 90W LED in something like a Coemar Prospot 250 or Robe 250 (which use condenser optics so would be easy to convert) or a Mac 250 (which doesn't use condenser optics so I would have to make my own). Watch this space.......( but also don't hold your breath :) )

[timsabre]

I have a nice simple circuit using the Allegro A6210 for 0-100% dimming of those Ledengin LED arrays. However you do need a PWM control signal from somewhere which could be hard to achieve in a retro-fit like that.

[Jamtastic3]

So what kind of drivers and equipment would you need to run this 90w LED (I know nothing in terms to voltage and LED strings etc)....

 

http://uk.farnell.com/ledengin/lzp-00cw00/led-90w-cool-white-mcpcb/dp/1901516#accessories

[gyro_gearloose]

The 90W LED is just a scaled up version of the 40W LED that I'm using. The 90W version uses four strings of LEDs at around 20-ish volts per string. You'd need four separate LED drivers, and a 24V 100W power supply. I use these LED dynamics drivers as they are fairly cheap and do what I need them to do. I wouldn't use the cool white LED though as its a bit too blue. The neutral or warm white LEDs might be a bit better.

 

Edit: Even though I'm using two 1A drivers, I have used their control pins to throttle the LED current back to just under 800mA. Its not really recommended to run the LEDEngin LEDs at 1000mA unless you can keep their junction temperatures down. Since my LED doesn't even get warm, I may try running it at 1000mA to see what happens.

Edited February 15, 2012 by gyro_gearloose

[DonkiDonki]

The 90W LED is just a scaled up version of the 40W LED that I'm using. The 90W version uses four strings of LEDs at around 20-ish volts per string. You'd need four separate LED drivers, and a 24V 100W power supply. I use these LED dynamics drivers as they are fairly cheap and do what I need them to do. I wouldn't use the cool white LED though as its a bit too blue. The neutral or warm white LEDs might be a bit better.

 

Edit: Even though I'm using two 1A drivers, I have used their control pins to throttle the LED current back to just under 800mA. Its not really recommended to run the LEDEngin LEDs at 1000mA unless you can keep their junction temperatures down. Since my LED doesn't even get warm, I may try running it at 1000mA to see what happens.

 

have you got around to trying them at 1000mA?