New project: LED conversion for LOMO Biolam

[Crater Eddie]

I need a new project to work on, so have decided to experiment with an LED retrofit for my LOMO Biolam. There is some excellent information about LED projects on the "old forum", as well as the archives of Micscape, I'll be using those as a starting point.
I took the plunge today and ordered some 3 watt Cree XT-E neutral white LED's and a couple of driver modules. Total expenditure so far less than $20.
Should be fun.

[microgreen]

Hi Les
I have a Lomo that didn't have a lamp ,only the double mirror. I made a lighting base that has a Halogen and an LED lighting system just by changing the lamp holder.
I'll try and post some photographs(now that I've learned how to post images,its not elegant- but it works
Tony
East Riding of Yorkshire(UK)

[Crater Eddie]

That would be great Tony, please do!
I would like to see your solution.

[zemblya]

I would be interested to see it-I've cobbled together an LED fridge lamp into the old lamp unit, using a cheap bedside light for the lampholder. Works well enough at low magnification and a lot easier than using the mirror!

[75RR]

I second the motion. Can everyone "please post photos" of your devices.

[Crater Eddie]

My project is progressing slowly. My LED driver boards arrived a few days ago directly from China. Considering it came from Hong Kong I thought my package got here reasonably quickly. Of course there was no documentation whatsoever, but as they are the same boards used in the tutorial on the old forum that should be no problem. I'll be playing with getting one hooked up and running in the next few days, will hopefully work on the installation during Christmas break.
In the meantime, it sure would be nice to see some photos from other members who have made similar modifications.
<cough cough> (Tony) <cough cough>

[75RR]

Will lead the way with some links to a Led Flashlight adaptation for microscope use.

http://www.photomacrography.net/forum/v ... c&start=75

and

http://www.photomacrography.net/forum/v ... hp?t=25718

Hi Crater Eddie, can you post the links to the tutorial from the old forum?

[microgreen]

OK!

Here are some photos(I hope) of my light base which I made a few years ago and it's still going good

1/ this is the simple wiring
3/

This light base can be used with halogen using an ordinary domestic low voltage transformer(240v input/12v output)and a domestic dimmer switch.It can also be used with a 12v LED and a 1k potentiometer for dimmer using a charger for the supply via a changeover switch.
You can see at the front of the base a reflector on which is the lamp holder.The two threaded rods are fixed to the reflector at the rear,these rods pass through the front of the base and have two BSA Bantam motorcycle spark plug connection screws, This is the means by which the lamp can be centred.

It's all very Heath Robinson - but it works - at little expense.
Just remembered I haven't shown the interior of the upright box at the rear.Now that I have got some images on the forum I'll take a photograph and post it in another posting

I hope this all makes some kind of sense but if anyone wants any clarification please PM

Tony
East Riding of Yorkshire(UK)

[75RR]

Just remembered I haven't shown the interior of the upright box at the rear.

Looking forward to seeing the contents. Thanks for the photos.

[microgreen]

The contents are nothing more than wire and a domestic 12v lighting transformer

[Crater Eddie]

Thanks for the photos Tony! I like the positioning screws, very handy. Very tidy setup.
Here is the link to the thread on the old forum which inspired my project:

http://www.microbehunter.com/forum/home ... icroscope/

This was for a different scope, so I will have to use my own ingenuity when it comes to mounting the LED. My Biolam is a little different than Tony's, as mine is the newer model with the fine focus wheel built into the base. It also has a built-in halogen bulb holder which I am considering modifying to hold the LED. I had some LED's and driver modules left over from a prototyping project at work, but none turned out to be suitable for this application. The above linked thread was useful in helping choose more suitable components.

CE

[microgreen]

Hi Les

My Biolam had the wheel fine focus, but I didn't like it so I got an older model off eBay and swapped the base. In fact the whole microscope has undergone many mods, I bought it new (my first microscope) ,in the early 90's.

I now have a few more than that now

Tony
East Riding of Yorkshire(UK)

[Crater Eddie]

I have often thought of doing that Tony, as I dislike that fine focus wheel arrangement intensely.
By the way, I had to look up "Heath Robinson", though I inferred your meaning from the context. Looks like he was a very creative fellow.
CE

[75RR]

This in an interesting link for the more technically minded.
Made by a Caver for his head lamp; I believe the principals are also valid in Led conversion in microscopy.

http://radiolocation.tripod.com/LEDdimm ... immer.html

[microgreen]

Why make a complicated (technical)circuit when a simple,and safe,circuit will do the job?

I've used this lighting base for a number of years with no problems at all.
I have other microscopes(including an Olympus inverted and a Watson System 70)with built in lighting and this "non technical" base works as good as any of them

Tony
East Riding of Yorkshire(UK)

[75RR]

I've used this lighting base for a number of years with no problems at all.

The idea was to avoid electric pulses that are a problem with video.
See: http://www.photomacrography.net/forum/v ... hp?t=25718

If your setup does not have this problem I would like details on how to make it.
I have no electrical skills so I would need step by step instructions.

[microgreen]

OK
Here are some more piccies.

1
2
3

I hope they show how simple it is

Tony
East Riding of Yorkshire

[75RR]

Hi microgreen.

A few of questions.
1) Are you dimming the mains current before it reaches the 220v to 12v ac transformer?
2) What is the DC source? How many volts/amps.
3) Details of the led bulb?
4) Have you taken video with the led light? Any Pulse problems?
5) Are the items I circled in yellow, fuses?

Thanks

[microgreen]

In answer to your questions :-

1/ Yes

2/ I use a universal regulator
input - 230v~50Hz 33.4w
output - 3v 4.5v 6v 7.5v 9v 12v
current1200mA 14.4VA(max)

3/ 10mm 12v White

4/ No -I'm not interested in doing video - I only take a photograph if I need to

5/ No - they are switches - if you look at the photo of the rear cover you will see the switches

I use the Halogen only when I need a brighter light.I find the LED is normally bright enough

Not much help to you I'm afraid.

Tony
East Riding 0f Yorkshire(UK)

[75RR]

Many thanks

[Crater Eddie]

Most modern LED driver modules / circuits use some form of Pulse Width Modulation scheme to achieve high efficiency, that is, good brightness control with the least wasted power. Unfortunately, this can result in annoying interference patterns in recorded videos resulting from the PWM beating against the recording sampling rate. This can be prevented by using a nice clean DC supply for the LED and adjusting the brightness with a good old fashioned linear regulator. This setup results in a smooth non-modulated light output from the LED, and no interference in the recorded video. Unfortunately, this type of controller is inefficient, wasting the unwanted power as heat. That's why you don't see many of these circuits anymore. The good news is that they are fairly simple to build, requiring a minimum of components. When I get to work on my LED source over Christmas break, I'll also try and put together one of these circuits and document it as well for anyone interested.

[75RR]

When I get to work on my LED source over Christmas break, I'll also try and put together one of these circuits and document it as well for anyone interested.

Interested :) Thanks

[gekko]

https://ppcdn.500px.org/92907827/8b7dc7 ... 4697/4.jpg

Yes, I get interference (horizontal dark bands) in my videos with the built-in tungsten-halogen illumination using AC.

[Crater Eddie]

Gekko, I remember that from previous discussions on the old forum, I had assumed that you had solved it. I should have a couple of suitable regulators in my junk box, I'll take a look when I get home. If I don't find any I can order a couple to play with.

[gekko]

Gekko, I remember that from previous discussions on the old forum, I had assumed that you had solved it. I should have a couple of suitable regulators in my junk box, I'll take a look when I get home. If I don't find any I can order a couple to play with.

No, I haven't--the only way to solve it would be to use DC, I think, but it doesn't really bother me much. Many thanks but I really do not think I want to try to use LED: I'd rather use what time I have to use the microscope rather than to try to convert it (too many things to consider to make sure I maintain Koehler and to fully illuminate the objective aperture at the same time: actually now I'm very happy that I got those Zeiss tungsten-halogen bulbs that I found on ebay [I posted about them in the Suppliers, buying, selling section] as they allow me to fully illuminate the objective aperture with the diffuser out). Thanks again.

[Crater Eddie]

Ok Gekko, that's fine. I'll look into it anyway, for 75RR. I might need to make myself one if the LED driver board I have gives me this problem.

[microgreen]

Hi Les
Isn't the circuit I use for my LED lighting the same"nice clean DC supply for the LED and adjusting the brightness with a good old fashioned linear regulator" ?
I haven't had heat problems in any part of the circuit - and I've used the same 12v LED bulb for approx. 4-5 years.
As you say the circuit is"simple to build, requiring a minimum of components"

Tony
East Riding of Yorkshire(UK)

[Crater Eddie]

Probably so Tony, though your "transformer" is actually an electronic switching power supply instead of a plain old transformer with diodes and big filter capacitors, that's why it is so small. Since it is a switcher, even though the output is dc there is still the possibility of noise in the output that could conceivably cause artifacts in the video. If you haven't noticed them, then I guess it is clean enough to get away with it.
Regardless, I don't happen to have a supply like this, they aren't that common over here that I have noticed.
If 75RR has access to one of these it would be a good option.
CE

[microgreen]

I haven't noticed any artifacts in video as I don't do video through the microscope,I do take the occasional still image for reference,but then I use the halogen lighting.

For general microscopy I'm very happy with the 12mm LED.

You may have spotted the lamp on the Lomo? It's a barrel from a camera lens into which I fitted an iris and a couple of lenses(after much experimenting)I managed to fill the back plane of the objectives with a nice even light - with the exception of the x3.5 plan,but the condenser subsidiary lens solves that.

I have a Lomo/Swift hybrid microscope(official) and a few other microscopes that may be of interest to the forum, I'll post some photographs(not in this thread)

Tony
East Riding of Yorkshire(UK)

[Crater Eddie]

I had wondered about your lens assembly, thanks for that information.
I am really not too concerned about video these days myself, but once in a while something interesting pops up and I like to take a few seconds of vid to review later. That would be a whole lot easier with a tricoc assembly, but that's another thread.