AMScope M200B-MS conversion 20 watt lamp to LED

[rabitt]

I was going to put more detailed info together but ended up having surgery on the 18th and will be awhile recovering.
So here are some photos of the conversion. The heart of the LED control is the BuckPuck 3023-D-E only 13/16 Square by 7/16" deep.
I used the 1000ma output model and set the max output to 500ma with an additional trimpot, this will limit max watts to 1.6 watts.

I would suggest for normal conversion a 3 watt LED and the BuckPuck with the 500ma output.
You have a selection of output currents 350, 500,700 and 1000ma.

You can find more info at LED Supply http://www.ledsupply.com/led-drivers/bu ... ed-drivers
All documentation is available on their web site.
This includes Cree LEDs their 3 watt heatsink, Wall Warts etc.

I used the soft white LED because of the ground glass lens supplied with the M200B scope.

[billbillt]

That is a great looking job!..

BillT

[75RR]

Nice arrangement.

Interesting that you got a BuckPuck. I picked up a A009-D-V-2100 to go with my XML Cree 3000mA 10W.

Was wondering if you got any heat issues with that box and if the LED dropped smoothly to 0. No sudden drop at the end!

What are you feeding it with?

[rabitt]

The wall wart is a 100, 240volt input 12volt 2.5 amp factory set to 2 amps max output.

The heat sink can handle up to 3 watts in free air, the heat shield for the original 20 watt
lamp is vented so there is little if any heat if running at 1.5 to 2 watts.

I run just above turn on with 4X and 10X objectives cranking up slightly with 40X. I adjust for more or
less light output when setting up my OMAX camera for best photos / video in order to fine tune everything.
Also turn up in order to see through semitransparent objects such as Amoeba Tests Algae etc.

I will replace the 5k pot as soon as I find a better quality replacement, it is intermittent at the low resistance
end. Note that the LED is turned off at zero ohms (short circuit). That is what I use the switch for, instant
on / off.

[rabitt]

The LEDs I purchased are the Cree 3000mA 10W, I'm planning to use them in other projects and will be replacing the
one in the scope with a 3 watt.
The BuckPuck runs pee warm at 2 watts.

[75RR]

I run just above turn on with 4X and 10X objectives cranking up slightly with 40X.

So it does not turn off smoothly? There is a cliff if you like - before it reaches 0?

[rabitt]

Hi 75RR,
Your question "So it does not turn off smoothly? There is a cliff if you like - before it reaches 0?"

If I had a decade box in place of the 5k pot the best way to establish exactly what happens at the
on off point would be to slowly step down towards zero (short circuit in this case). Also establish
at what point the LED will remain on.

In the next week I will place a trim pot (few hundred ohms) in series with the 5k pot in order to
determine the on / off point and reliable on point.
Will post the results.

Stay tuned.

[75RR]

Hi rabitt,

With my present arrangement (which I am no longer using) the minimum is far too bright.

The reason I got the A009-D-V-2100 was to hopefully achieve a smooth turn off,
with a minimum setting I can view in order to set up Köhler.

Have already bought the A009-D-V-2100 so I guess I will see how it goes when I get it.

[billporter1456]

rabitt, I really like your LED setup and your description of same. Very nice job!

75RR, I've been using two different LED setups, one of which uses a cheap PWM dimmer. I know what you mean about the minimum being too bright. My fix for that was to us ND filers ( a 2 and a 4) that i sat on top of the field lens when using a 10X objective. The other setup using a little DC-DC CC CV buck puck. I replaced the voltage trimpot with a 1k pot which limits the voltage output to about 4 volts and set the current trimpot to limit current to a bit over 1,000 milliamps. This second setup allows much better control at the low illumination levels and I don't need the ND filters with it. I'm using a 3W Cree neutral white LED.

[75RR]

Thanks billporter1456,

that is disappointing.

Limiting the voltage did give me a lower low range - problem with that was that I lost out on the high range which I also wanted.

Just to confirm: the A009-D-V-2100 dims by varying the current as opposed to the frequency of the flashes like a PWM does?
In other words it does not flash the LED. If true that is worth something.

[billporter1456]

Thanks billporter1456,

that is disappointing.

Limiting the voltage did give me a lower low range - problem with that was that I lost out on the high range which I also wanted.

Just to confirm: the A009-D-V-2100 dims by varying the current as opposed to the frequency of the flashes like a PWM does?
In other words it does not flash the LED. If true that is worth something.

I just looked at information on the A009 and it is definitely not a PWM device. Scroll down to illustration #14 on the the following link and you will see that a 20K pot will give you 0-100% dimming of an LED: http://www.ledsupply.com/content/pdf/le ... tation.pdf

Bear in mind that I don't have any first-hand knowledge of this setup and am not very smart about LEDs and electronic circuits. The dimming operation may produce some kind of unwanted effects for all I know.

[75RR]

Hi billporter1456,

Had read the part you link to, which was why I got it.
Was having trouble with the flashing (bothered my eyes) and with the minimum brightness.
This seemed ideal.

To be honest I don't know what to think now.
Guess I will just have to wait and see how it works.

[rabitt]

Hi Everyone,
Well I did more testing of my BuckPuck 3023-D-E-1000-P. Since I don't have a decade box I replaced the 5K pot with a 500 ohm
10 turn Bourns trim pot. This allowed me to get down in the mud around the cutoff point of the LED. As it turned out I was able
to get the LED light output below usable brightness even for the 4X & 10X objectives. Just below that point the LED gave a few very dim
pulses of light and turned off.

500 ohms is about 10% of the 1000ma output of the Puck or 100MA / 0.3 watts; with that info I wired it per my attached PDF file.
Since the A009-D-V-2100 & 3023 Puck are wired the same except for the value of the control pot you should be able to use a 2K or less
trim pot and do the same test with the A009. Refer to A009 PDF file figure 19, %IOT=R1\200.

I put as much info on my drawing that would fit. Also replaced the 500 ohm trim pot with a single turn pot & still have good control
of the low end brightness. For max brightness I believe anything over 1.5 / 2.0 watts is a waste.

[75RR]

Thanks for the extra info.
Have included your pdf in my LED Illumination file.
Now to await the BuckPuck and see what results I get.

[rabitt]

75RR,
I will be waiting for your results and comments, hopefully others on the forum will have input and we
can come up with a reliable, inexpensive lighting system.

Rich B