Quick cheap & easy LED conversion for my Halogen 'scope

[mrsonchus]

Hi John,

My last post seems to have disappeared.. I am anxiously waiting to see how the 5W G4 bulbs work out.. I once did a comparison test with a 2W G4 bulb vs a 50W halogen... The 2w lost out on brightness.. I was thinking... Half of the G4's COB LED's are on the back side... Maybe a small mirror placed there could help reflect the light towards the front.. Does your dimmer completely turn off the bulb? I have some of the same dimmers here and they do not completely extinguish the light.. I think these controllers are PWM devices... The beauty of all this is it is so inexpensive a person can experiment to no end...

The Best,
BillT

Hi Bill, yes the controller completely turns off the bulb, the voltage across the bulb drops to zero as measured by me. There is a difference in performance characteristics I notice, due to the power-supply (that which plugs into the mains and outputs the DC 12V for the dimmer's input) used. For the prototype I used an old manually switchable power supply that was able to output a range (discreet not continuous that is) of voltages from about 3V to about 14V. Using this PS the dimmer again turned the bulb completely off, but the bulb only started to work with the dimmer's 'dial' turned to about 25% on the dimmer's scale, and worked as expected from there up to the maximum.

When I used (as in the finished version) the new PS (bought online for £8) at a single 12V 'for LED lighting' the dimmer was/is now able to start the bulb from it's 0% position, again smoothly up to 100%. Also the new PS runs almost cold, hardly any heat at all in this new system, either in the mains PS or the bulb in my scope's 'field-illuminator' housing.
I can only conclude from this that the new £8 'LED power supply' is genuinely a very good device for LED control and is of a very good build and operation standard - I think I got very lucky for the price - the 'special' PS was in this case worth every penny I think.
A really cheap & easy conversion, looking forward to when the new 5W (also dimmable) LEDs to arrive.

The lamp-housing and mount that held the original halogen has as you may imagine a (very basic but polished by me some while back with metal-polish 'til I could see myself in it!) built-in reflector - it's a cheapo piece of what looks like Aluminium.. So, I should get a reflective contribution also, from those LEDs not facing directly up into the field-lens. I think! I could always take such a reflector from some other bulb or torch etc and simply fit it beneath the 5W easily enough also...

I really like the new LED, it's far nicer to use and I no-longer fret over my slides being cooked anymore, especially as they are often 'still wet' when first observed! Cheap & simple, works very well!

[Dale]

John, my G4 sockets are on your boat now, but I did get all the other parts. My question is on lamp placement. My stereoscope
has a large rotating mirror under the stage, but it is easily removable. I have not fired up the led yet, so I am wondering
if it projects beam-like, or wide-angle? I can glue the socket to the mirror, or to the plain steel side. If it projects a wide
beam the socket/led could even be fastened all by itself. I can't envision any need to swivel the light. Any thoughts?
Dale

[lorez]

Dale,

You may want to consider a translucent stage glass, or plastic disc to diffuse the light from the LED. Without a diffuser you will get a very bright spot that will really make viewing the specimen difficult.

Am I looking for a disc for you ?

lorez

[billbillt]

A section cut from a plastic throw away juice carton works for me as a diffuser.. You can stack several layers if necessary... Costs zero...

BillT

[Dale]

I bought a big polypropylene cutting board to cut discs from, so You can
stand down Lorez, but many thanks for offer. I spend more time looking at
than looking through my scopes!
Dale

[billbillt]

John, I went back and retried my 8A dimmers.. They both turn the lamp off.... I had the polarity from the power supply reversed... With that corrected both function as expected...

BillT

[mrsonchus]

John, I went back and retried my 8A dimmers.. They both turn the lamp off.... I had the polarity from the power supply reversed... With that corrected both function as expected...

BillT

Easily-done Bill, everything working A1 now though is good news. It's a great addition to my 'scope and I love it, smooth-as-silk dimmer and a lovely cool light that doesn't change colour with brightness!

[mrsonchus]

Hi all, the 5W LED bulbs arrived and after a slight adjustment to center the bulb properly I tried one out. They give a beautifully white light as do the 3W round versions although they don't look much brighter, some but not much.
I have a very basic 'reflector' under the bulb that is original to the 'scope but it's pretty poor (it looks like a piece of old Coke-tin to me.. ) and in no way shaped to give an optimal re-direction of light that's moving away from the direction I want it to go, i.e. straight-up into the field-lens below the field-iris. Room for an easy and significant improvement here though.,

Here's the 5W newbie in-situ,

ws_LED-5W-(2).jpg (139.56 KiB) Viewed 16415 times

I will take the time to fit a good reflector below this as the gain should far outweigh the small effort & tiny cost of fitting one.
This has been a super addition to my trusty Chinese 'scope, all's working very well!

[Dale]

You used a rectangular layout not a circular, any reason?
Dale

[mrsonchus]

You used a rectangular layout not a circular, any reason?
Dale

That's how the 'scope came - it looks horribly inefficient to me - (the 'reflector') I'm going to fit a 'proper' version when I get around to it.

[Dale]

I am ready to launch my conversion, just waiting for the scope, a Biostar 1820 with a dead bulb.
I bought all the parts you did to build an understage light on a dissection scope. It tested fine but
nothing was mounted permanently.
I would ask these three questions:
1. During phase observation do you get more or less brightness with the LED,s?
2. Do you get satisfactory brightness for photography?
3. Why did you use a voltage controller? Doesn't the SP200 feed the bulb socket
2 - 6V vac power?
Dale

[mrsonchus]

I am ready to launch my conversion, just waiting for the scope, a Biostar 1820 with a dead bulb.
I bought all the parts you did to build an understage light on a dissection scope. It tested fine but
nothing was mounted permanently.
I would ask these three questions:
1. During phase observation do you get more or less brightness with the LED,s?
2. Do you get satisfactory brightness for photography?
3. Why did you use a voltage controller? Doesn't the SP200 feed the bulb socket
2 - 6V vac power?
Dale

Hi Dale,
1 - I don't have PC capability unfortunately.
2 - Yes, I find that photography feeds hungrily upon contrast - this is equally as important as brightness I find. Also of course we will each have different light-sharing features on our 'scopes so I can't give you a helpful answer here beyond the fact that my setup is fine for photography old chap.
3 - LED has a different type of dimmer I believe, also I now use 12V rather than the SP200's 6V simply because it gives many more lighting options. I can't advise on any electrical connections etc as I'm totally unqualified to do so Dale.

Good luck, it's an easy conversion and working very well indeed.

[Dale]

Thank you John, you answered everything, and fast. 5 stars
Dale

[mrsonchus]

Thank you John, you answered everything, and fast. 5 stars
Dale

Always a pleasure to help if I can Dale.

[wmodavis]

Another good discussion fitting into my posts with questions elsewhere.
My 2cents as an electronics design engineer in a previous life (actually most of my now retired career) wherein I design multiple pieces of equipment using LEDs though more for indicators rather than for lighting as this thread discusses.

White light LEDs are not just simple white light LEDs. They are mainly (I think) composed of a Blue Light LED which is a monochromatic light at ~450nm then that emission excites built in material that phosphoreces to produce a broader spectrum light in the approx range of 500-600nm. The combined emission simulates white light in our perception. If true white light is composed of all frequencies in the visible spectrum then these white LEDs aren't quite there but maybe enough so for our purposes.

And all that (TMI) to pose this related thought to the UV/blue tinge effect - It seems logical to me because the visible emission from these "White" LEDs is composed of a strong peak at 450nm (blue). Now that is just above but not in the UV wavelength range but is a monochromatic blue light wave. Has anyone actually measured of there is some UV leakage? Seems to me that the blue predominance could tint a condenser and perhaps contain a bit of UV tendency (what ever that is).

Learning lots, thinking lots, maybe someday soon I'll have my own scope and practice and experiment lots.

[Dale]

The spectral output of led's should be well documented, it is finding the data on the
harmful results of UV exposure to the eye. That would be some nasty research!
UV filters are so cheap, and it would be so easy to put one in the scope.
Dale

[billbillt]

Hi Dale,

I recommended using such for an added insurance for people concerned about UV radiation.... A person needs to use what they are comfortable with..

BillT

[mrsonchus]

Another good discussion fitting into my posts with questions elsewhere.
My 2cents as an electronics design engineer in a previous life (actually most of my now retired career) wherein I design multiple pieces of equipment using LEDs though more for indicators rather than for lighting as this thread discusses.

White light LEDs are not just simple white light LEDs. They are mainly (I think) composed of a Blue Light LED which is a monochromatic light at ~450nm then that emission excites built in material that phosphoreces to produce a broader spectrum light in the approx range of 500-600nm. The combined emission simulates white light in our perception. If true white light is composed of all frequencies in the visible spectrum then these white LEDs aren't quite there but maybe enough so for our purposes.

And all that (TMI) to pose this related thought to the UV/blue tinge effect - It seems logical to me because the visible emission from these "White" LEDs is composed of a strong peak at 450nm (blue). Now that is just above but not in the UV wavelength range but is a monochromatic blue light wave. Has anyone actually measured of there is some UV leakage? Seems to me that the blue predominance could tint a condenser and perhaps contain a bit of UV tendency (what ever that is).

Learning lots, thinking lots, maybe someday soon I'll have my own scope and practice and experiment lots.

Many thanks for this info - it's absolutely fascinating and gives logic to our real-world experiences, very clearly and succinctly explaned for one such as myself that knows nothing of this subject. I am now seriously considering a prompt return to Halogen at least until I learn a little more. Would the purchase of a replacement (LED) bulb for a branded LED microscope be any closer to acquiring a trustworthy (i.e. safe) LED bulb? My system as it now is can take just about anything I choose to put into it, LED, filament or Halogen....

A very interesting and indeed important thread that I for one am delighted to have seen. Thank you again.

[wmodavis]

And MRSONCHUS - There's more. Here's a good Q&A presentation about LED stuff.
http://www.lrc.rpi.edu/programs/nlpip/l ... nation.asp


Here is a small hobbiest device that can be used for measuring UVA & UVB intensity. Those are the damaging and tanning UV bands. Looks like one might incorporate this board into an instrument for measuring UV radiation in a lighting system. ADDED: Not sure it would have the appropriate sensitivity to be of real measurement value for this.

https://learn.sparkfun.com/tutorials/ml ... 1459026307


Would be very interesting to compare various microscope lamp systems both before and after the lenses to see UV strength. Know of anyone with electronics background who might take it on?

[billbillt]

Hi John,
I would not get TOO upset about UV emission from LED's.... An inexpensive UV filter such as this would block most of it.. I can actually not find any documented accounts of LED's causing eye damage in humans from UV emission... The word used is POSSIBLE in almost all cases..
Place this filter over your light source and be done with it... You invested too much time in your LED upgrade to be turned away with "possible" eye damage...

http://www.ebay.com/itm/52mm-Haze-UV-Fi ... Sw37tWERuS

BillT

[wmodavis]

Re UV filters - here is a test of various ones. I'd pick the Tiffan Haze-1

http://photo.net/equipment/filters/

[mrsonchus]

And MRSONCHUS - There's more. Here's a good Q&A presentation about LED stuff.
http://www.lrc.rpi.edu/programs/nlpip/l ... nation.asp


Here is a small hobbiest device that can be used for measuring UVA & UVB intensity. Those are the damaging and tanning UV bands. Looks like one might incorporate this board into an instrument for measuring UV radiation in a lighting system.

https://learn.sparkfun.com/tutorials/ml ... 1459026307


Would be very interesting to compare various microscope lamp systems both before and after the lenses to see UV strength. Know of anyone with electronics background who might take it on?

Hmm, had a look at your link and the material appears to be from 2003 - this I personally will disregard as being of little use. I will however look further into the subject but am considering the fact that reputable microscope manufacturers or at least the companies happy to put their name onto such 'scopes are selling LED-illuminated microscopes without any problem/s that I'm aware of here in the UK.

This is where I find myself at this time, I think I will simply continue as I am, I don't have the time or inclination to delve deeply into this as I'm pretty sure news of any dangers from the almost ubiquitous LED lighting 'out there' would certainly have been publicised.
Thanks for the food-for-thought though, an interesting question and inherently interesting subject also, but not my area - it's back to Botany for me!

[mrsonchus]

Hi John,
I would not get TOO upset about UV emission from LED's.... An inexpensive UV filter such as this would block most of it.. I can actually not find any documented accounts of LED's causing eye damage in humans from UV emission... The word used is POSSIBLE in almost all cases..
Place this filter over your light source and be done with it... You invested too much time in your LED upgrade to be turned away with "possible" eye damage...

http://www.ebay.com/itm/52mm-Haze-UV-Fi ... Sw37tWERuS

BillT

Hi there Bill old fellow, you are of course right, and I've several UV filters for my camera/s that will help also if I feel the need!

[Dale]

Nobody mentioned the huge liability issue that mfr's would face if this UV hazard
could be documented as true retinal damage.

[mrsonchus]

Nobody mentioned the huge liability issue that mfr's would face if this UV hazard
could be documented as true retinal damage.

Assuming of course that there is a Hazard to be documented - and if there is surely it would have been documented by now? The ever-ravenous news-hounds in the UK would have fainted with happiness if this had been a story I suspect...

[billbillt]

I intend to continue on with LED... It is much fun putting together different configurations.... I have one I built for older stands that only have a mirror... It is a 10W element that works great!...

BillT

[Gasman]

Hi John
Trying to source that disc type led but can`t seem to find the identical one to yours and wondered where you got it from please?. The controllers seem easily available and there are other types of disc led`s which might do the job also!!.
thanks
Steve

[mrsonchus]

Hi John
Trying to source that disc type led but can`t seem to find the identical one to yours and wondered where you got it from please?. The controllers seem easily available and there are other types of disc led`s which might do the job also!!.
thanks
Steve

Hi Steve, here's a list of links to the various parts I used, all from e-bay UK....

This is the power-supply I used - it runs very cool and has been 100% safe & reliable..
https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
Here's a snip,

psuppicsnip.JPG (85.24 KiB) Viewed 15826 times

This is an inline-switch for the fully on-off assurance,
https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
A snip,

switchsnip.JPG (52.82 KiB) Viewed 15826 times

The smd round led,
http://www.ebay.co.uk/itm/161432722444? ... f95e9&cp=1
A pic snip,

smdledsnip.JPG (54.85 KiB) Viewed 15826 times

Finally this is the dimmer I used,
https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
A snip,

dimmerpicsnip.JPG (53.9 KiB) Viewed 15826 times

I hope this helps Steve, let me know if you want any more info old chap.

[Gasman]

Excellent cheers for that John

[Oxalis80]

I recently bought the dimmer and two cold light led lamps, to replace the incandescent bulb on my cheap microscope. I'd like to convert it to low voltage and to have a dimmer, but...
The original lamp has a VERY reddish light, and the manufacturer put under the lens an opaque blue filter. When I tested the LED under the lens... I had a perfectly blue light!

I'm afraid that it won't be enough to use a warm light led. Maybe I should remove / replace the opaque filter.