Do you think that would work for a led conversion?

Here you can discuss DIY adaptations to the microscope.
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Leitzcycler
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Re: Do you think that would work for a led conversion?

#31 Post by Leitzcycler » Wed Oct 20, 2021 8:16 pm

I was wondering if you mysteriously stumbled upon a light storing condenser that equalizes light output
Would be nice, however I have to be satisfied with kondensaattori.

As you see, it is too late for me to hang around here and my head is not clear any more. So it's time to go to sleep.

smollerthings
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Re: Do you think that would work for a led conversion?

#32 Post by smollerthings » Wed Oct 20, 2021 8:19 pm

dtsh wrote:
Wed Oct 20, 2021 8:15 pm
I use a wall-wart with mine, but I use an LED driver which converts the volts and amps to ranges appropriate to the LED and adding a driver increases the cost. I believe the driver was the single most expensive part on mine.
What about something like this then to get to the proper voltage range?

https://www.aliexpress.com/item/32897614510.html

smollerthings
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Re: Do you think that would work for a led conversion?

#33 Post by smollerthings » Wed Oct 20, 2021 8:24 pm

Leitzcycler wrote:
Wed Oct 20, 2021 8:16 pm
Would be nice, however I have to be satisfied with kondensaattori.
Actually there is a whole branch of physics that try to replicate the electronic components in the light area so we can go beyond the limitations of current electronics (much higher frequency). It probably already exists. Good night sir!

Hobbyst46
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Re: Do you think that would work for a led conversion?

#34 Post by Hobbyst46 » Wed Oct 20, 2021 8:37 pm

smollerthings wrote:
Wed Oct 20, 2021 8:19 pm
dtsh wrote:
Wed Oct 20, 2021 8:15 pm
I use a wall-wart with mine, but I use an LED driver which converts the volts and amps to ranges appropriate to the LED and adding a driver increases the cost. I believe the driver was the single most expensive part on mine.
What about something like this then to get to the proper voltage range?

https://www.aliexpress.com/item/32897614510.html
I would not choose it.
For one reason, its low voltage range (3-5V) is practically useless for LEDs. A LED starts shining when the forward voltage is typically ~3V (roughly; depends on the LED). But there are other components in the circuit. So the supplied voltage must be higher. The useful range for LEDs is north of 5V. Usually 9-12VDC.
Second, the current provided by the gadget in the link is merely ~2.5A at 12V maximum (I believe, since it is stated to give 30W).
If the forward voltage on a LED is 3V, and it should be rated at 6W, the current through the LED must be 2A at least.
2.5A is too close to that minimum.
A LED strip typically requires less than a high power LED.
To control LED intensity, variable voltage is not used. Rather, control either the current (best method) or the duty cycle (that is PWM).

dtsh
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Re: Do you think that would work for a led conversion?

#35 Post by dtsh » Wed Oct 20, 2021 8:48 pm

smollerthings wrote:
Wed Oct 20, 2021 8:19 pm
dtsh wrote:
Wed Oct 20, 2021 8:15 pm
I use a wall-wart with mine, but I use an LED driver which converts the volts and amps to ranges appropriate to the LED and adding a driver increases the cost. I believe the driver was the single most expensive part on mine.
What about something like this then to get to the proper voltage range?

https://www.aliexpress.com/item/32897614510.html
Not without an LED driver.
That would allow adjusting the voltage, but LEDs require adjusting the current. That said, I'm getting to the limits of my actual understanding of how LEDs operate; which is why the circuit I am using was designed by someone else. It works, but probably isn't the most cost effective solution. It met my criteria though, which was >6W (I believe all together it pushes 8W), dimmable, and reliable (time will tell on that last). Total parts cost was below $30, which was acceptable to me. Someone who really knows what they're doing could probably design something as good for less, but that person isn't me.

BramHuntingNematodes
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Re: Do you think that would work for a led conversion?

#36 Post by BramHuntingNematodes » Wed Oct 20, 2021 10:59 pm

smollerthings wrote:
Wed Oct 20, 2021 7:57 pm

I am a bit unclear on the dimming part. Potentiometer vs pwm. I guess potentiometer is better because it won't induce additional flickering in case one wants to make videos? I am a bit rusty on the sizing of the potentiometer. What did you use for the 10W?
Some LED drivers have a supplemental 5v circuit that can be used to dim the LED by introducing some resistance to it. I use a logarithmic taper pot to introduce the resistance to this circuit. Adding resistance between the driver and the LED will not work.

I have done many LED installations for these microscopes and other stuff and have only had one burn out. It was an SMD that I soldered by hand and it is my belief that its contact with the substrate was not good. 10 watts is a bright LED but it's not very much heat really. The main problem is that the LED is very small, but a good thermal substrate often provides decent heat dissipation particularly for intermittent use with some dimming usually applied. The Nikon lamp gets a good bit of airflow also, which may not be the case deep in your scope's guts.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

smollerthings
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Re: Do you think that would work for a led conversion?

#37 Post by smollerthings » Thu Oct 21, 2021 8:38 am

Thanks everyone for sharing your experiences. I have now a good idea of what should be done.

viktor j nilsson
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Re: Do you think that would work for a led conversion?

#38 Post by viktor j nilsson » Thu Oct 21, 2021 9:09 am

My favorite solution by far is the BuckBlock from LedDynamics:
https://www.luxeonstar.com/2100ma-dimma ... iver-leads

Clean, constant 2100mA current, and easy to add a potentiometer for dimming. No PMW dimming with flickering and banding, but actually changing the current, which is ideal for LEDs.

They also have smaller BuckPuck version that goes up to 1000mA.

Leitzcycler
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Re: Do you think that would work for a led conversion?

#39 Post by Leitzcycler » Tue Oct 26, 2021 7:25 am

My favorite solution by far is the BuckBlock from LedDynamics:
https://www.luxeonstar.com/2100ma-dimma ... iver-leads
Where do you buy these? It would be convenient to find a European supplier.

viktor j nilsson
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Re: Do you think that would work for a led conversion?

#40 Post by viktor j nilsson » Tue Oct 26, 2021 8:58 am

Leitzcycler wrote:
Tue Oct 26, 2021 7:25 am
My favorite solution by far is the BuckBlock from LedDynamics:
https://www.luxeonstar.com/2100ma-dimma ... iver-leads
Where do you buy these? It would be convenient to find a European supplier.
I've ordered them from digikey, they are shipped from the US so you pay VAT but shipping to Sweden was not too expensive and very quick (4 days or so). Unfortunately I haven't found a European supplier. I've done a lot of research on different options, and these are the only ones I've found that tick all my boxes.

MichaelG.
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Re: Do you think that would work for a led conversion?

#41 Post by MichaelG. » Tue Oct 26, 2021 9:26 am

Digi-Key U.K. lists them:
https://www.digikey.co.uk/en/products/f ... B2SkBdAvkA

… so they are probably available throughout Europe

MichaelG.

.
This looks promising, Viktor:
https://www.digikey.se/products/sv/powe ... uck%20puck
Too many 'projects'

viktor j nilsson
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Re: Do you think that would work for a led conversion?

#42 Post by viktor j nilsson » Tue Oct 26, 2021 10:09 am

MichaelG. wrote:
Tue Oct 26, 2021 9:26 am
Digi-Key U.K. lists them:
https://www.digikey.co.uk/en/products/f ... B2SkBdAvkA

… so they are probably available throughout Europe

MichaelG.

.
This looks promising, Viktor:
https://www.digikey.se/products/sv/powe ... uck%20puck
Available yes, but I believe that most of the time (or always) they'll ship from the US.

From the FAQ:
Where is Digi-Key Located?
Digi-Key's headquarters and product distribution center is in Thief River Falls, Minnesota, USA. Regional support centers are in Israel, Germany, the Netherlands, China, Hong Kong, South Korea and Japan.
It was super smooth to order from them, though. The goods arrived in a couple of days. I got a text message with information on how to pay for VAT, and the delivery guy called me and asked to make sure that I had paid VAT, before dropping it off outside my house.

MichaelG.
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Re: Do you think that would work for a led conversion?

#43 Post by MichaelG. » Tue Oct 26, 2021 1:27 pm

viktor j nilsson wrote:
Tue Oct 26, 2021 10:09 am
Available yes, but I believe that most of the time (or always) they'll ship from the US.
Apologies, Viktor … I was trying to help, not interfere.

Things may be different in Sweden, but the U.K. site currently lists the BuckPuck items as ‘immediately available’
My interest in purchasing from the domestic site is that the VAT and delivery side of things is handled locally.
… so there should be no surprises.

I will stay silent on the matter now.
MichaelG.
Too many 'projects'

viktor j nilsson
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Re: Do you think that would work for a led conversion?

#44 Post by viktor j nilsson » Tue Oct 26, 2021 2:05 pm

MichaelG. wrote:
Tue Oct 26, 2021 1:27 pm
viktor j nilsson wrote:
Tue Oct 26, 2021 10:09 am
Available yes, but I believe that most of the time (or always) they'll ship from the US.
Apologies, Viktor … I was trying to help, not interfere.

Things may be different in Sweden, but the U.K. site currently lists the BuckPuck items as ‘immediately available’
My interest in purchasing from the domestic site is that the VAT and delivery side of things is handled locally.
… so there should be no surprises.

I will stay silent on the matter now.
MichaelG.
Immediately available from their US warehouse, with 48h delivery to the UK. And "All duties, taxes and brokerage fees will be due at time of delivery.".

I still think it's a very good option, but it's Important to know that it's not a domestic site, it just looks like that. But honestly, the shipping was faster than from many domestic swedish vendors...

DrPhoxinus
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Re: Do you think that would work for a led conversion?

#45 Post by DrPhoxinus » Tue Oct 26, 2021 3:05 pm

I still remain a fan of this power supply
https://www.googleadservices.com/pagead ... EBY&adurl=

3-12 V at up to 5 amps adjustable

Works with anything including old incadescent and halogens

smollerthings
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Re: Do you think that would work for a led conversion?

#46 Post by smollerthings » Fri Oct 29, 2021 12:16 pm

DrPhoxinus wrote:
Tue Oct 26, 2021 3:05 pm
I still remain a fan of this power supply
I can't see the link DrPhoxinus.

I found a cheap dimmable constant current driver:

https://www.aliexpress.com/item/1005001298092034.html

DrPhoxinus
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Re: Do you think that would work for a led conversion?

#47 Post by DrPhoxinus » Fri Oct 29, 2021 1:21 pm

That device looks great.

Here is a different link for the 5amp device

https://www.xump.com/science/3-12v-5a-a ... GkQAvD_BwE

smollerthings
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Re: Do you think that would work for a led conversion?

#48 Post by smollerthings » Fri Oct 29, 2021 2:15 pm

DrPhoxinus wrote:
Fri Oct 29, 2021 1:21 pm
That device looks great.

Here is a different link for the 5amp device

https://www.xump.com/science/3-12v-5a-a ... GkQAvD_BwE
Interesting. Does it work with LED? I thought LEDs needed to be driven by current and not voltage.

DrPhoxinus
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Re: Do you think that would work for a led conversion?

#49 Post by DrPhoxinus » Fri Oct 29, 2021 3:17 pm

I use that supply to drive a 5amp 6 volt incandescent bulb in an Ortholux I, halogens in American Opticals,
LED 12v COB

I have 14 scopes and I use the supply on 10 of them.

The led drivers need a voltage supply and this can do the job as well as others

dtsh
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Re: Do you think that would work for a led conversion?

#50 Post by dtsh » Fri Oct 29, 2021 4:04 pm

smollerthings wrote:
Fri Oct 29, 2021 2:15 pm
Interesting. Does it work with LED? I thought LEDs needed to be driven by current and not voltage.
DrPhoxinus wrote:
Fri Oct 29, 2021 3:17 pm
I use that supply to drive a 5amp 6 volt incandescent bulb in an Ortholux I, halogens in American Opticals,
LED 12v COB

I have 14 scopes and I use the supply on 10 of them.

The led drivers need a voltage supply and this can do the job as well as others

DrPhoxinus is using that to put power into an LED driver, but not to drive the LED directly, correct?
I have a similar setup, except mine is a set voltage wall wart putting out 12v@1.25A into the above mentioned LUXDrive driver.

DonSchaeffer
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Re: Do you think that would work for a led conversion?

#51 Post by DonSchaeffer » Fri Oct 29, 2021 10:15 pm

Here's my suggestion for an LED light source. Keep your old one and add this.
2021-10-29_170917.jpg
2021-10-29_170917.jpg (109.65 KiB) Viewed 7113 times

Gatorengineer64
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Re: Do you think that would work for a led conversion?

#52 Post by Gatorengineer64 » Sat Oct 30, 2021 12:41 am

about as cheap and easy as its gets.

https://www.ebay.com/itm/283514624337

It shells out easily, and I use it with

https://www.amazon.com/gp/product/B00OX ... UTF8&psc=1

I use with my sub 1" zeiss lamps, works great. You absolutely DO NOT need a heatsink at 3 watts, the surface of the LED does get hot, but I don't think most folks make a habit of touching it, and you may loose a little oomph but makes it easier without one. I glued mine to a 3/4" copper pipe coupler, but the back of the LED does not have a heat sink. I have accidently left it on overnight and the view is great in the morning. There is some flicker at the low end, but most of the time I am in the 60-100 percent range.

I will be doing a 10 watt with better LEDs and a Triac dimmer $18 from LED tech shortly. These will get a heat sink.

Leitzcycler
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Re: Do you think that would work for a led conversion?

#53 Post by Leitzcycler » Sat Oct 30, 2021 8:01 am

Does it work with LED? I thought LEDs needed to be driven by current and not voltage.
I have used variable voltage as I didn't know it won't work :)

However, the controllable range is very narrow. Is it more wide using variable current?

Hobbyst46
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Re: Do you think that would work for a led conversion?

#54 Post by Hobbyst46 » Sat Oct 30, 2021 9:19 am

Leitzcycler wrote:
Sat Oct 30, 2021 8:01 am
Does it work with LED? I thought LEDs needed to be driven by current and not voltage.
I have used variable voltage as I didn't know it won't work :)

However, the controllable range is very narrow. Is it more wide using variable current?
LED brightness is roughly proportional the the current that passes through the LED. Hence controlling the current is the proper brightness control.
The voltage across the LED terminals is constant when the LED is turned on (LED is a diode). So changing the supply voltage will not directly control the LED brightness.
PWM control is a viable alternative since it controls the duty cycle, the time fraction that the LED stays on. Since LEDs instantly turn on and off. However, PWM causes banding that shows in photography.

jfiresto
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Re: Do you think that would work for a led conversion?

#55 Post by jfiresto » Sat Oct 30, 2021 9:58 am

Hobbyst46 wrote:
Sat Oct 30, 2021 9:19 am
.... LED brightness is roughly proportional the the current that passes through the LED. Hence controlling the current is the proper brightness control....
That is often an acceptable to the better approach near an LED's "binning" or "grouping" current, the current at which it is tested and sorted.

LED manufacture, however, remains a comparatively poorly controlled process. It only makes batches of LEDs, sharing similar colors and intensities over a limited current range, that can become much less so below the test-and-bin current. A manufacturer will typically not guarantee a batch will appear similar, below a quarter of the LED's rated current. I have put a batch in series and watched some, but not all, go dark, as I further lowered the current. :(

The upshot is that you probably want to use PWM to dim LEDs more than about 4:1, particular if there are more than one, and pulse them at the rate of kilohertz for a camera or if the illuminated objects and/or observer move.
-John

smollerthings
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Re: Do you think that would work for a led conversion?

#56 Post by smollerthings » Sat Oct 30, 2021 12:52 pm

DonSchaeffer wrote:
Fri Oct 29, 2021 10:15 pm
Here's my suggestion for an LED light source. Keep your old one and add this.
That was my initial setup but I think it doesn't take advantage of a lot of the initial's design qualities.
Leitzcycler wrote:
Sat Oct 30, 2021 8:01 am
I have used variable voltage as I didn't know it won't work :)

However, the controllable range is very narrow. Is it more wide using variable current?
Whatever works! But yes, I think it will work better with variable current or PWM.

Thanks @jfiresto @Hobbyst46. Very interesting.

smollerthings
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Re: Do you think that would work for a led conversion?

#57 Post by smollerthings » Sat Oct 30, 2021 1:00 pm

All, I received a cheap PWM led dimmer so I though I would share some experience.

Working Voltage: DC9V-24V
Max Output current: 2A
Output channel: 1CH
Work temperature: -20~60c
Static power consumption: 1W

Everything works fine. I tried with a 12V 3W led bulb and 12V 20W halogen bulbs. The PWM's frequency is too low and videos with the LED bulb have banding. But it is a cheap and acceptable choice for eye observation or a setup with a 20W halogen.




MichaelG.
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Re: Do you think that would work for a led conversion?

#58 Post by MichaelG. » Sat Oct 30, 2021 2:10 pm

Buck converters like this: https://www.ebay.co.uk/itm/353674625191 are widely available at various prices

But note that the tiny preset ‘pot’ is inconvenient for use as a dimmer.

The important feature is their use of the LM2596 chip, which provides high frequency PWM

MichaelG.

.
Ref. https://www.ti.com/lit/ds/symlink/lm2596.pdf
Too many 'projects'

jfiresto
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Re: Do you think that would work for a led conversion?

#59 Post by jfiresto » Sat Oct 30, 2021 3:40 pm

MichaelG. wrote:
Sat Oct 30, 2021 2:10 pm
Buck converters like this: https://www.ebay.co.uk/itm/353674625191 are widely available at various prices

But note that the tiny preset ‘pot’ is inconvenient for use as a dimmer....
Not to mention that it will probably start wearing out within a few hundred adjustment cycles.
-John

MichaelG.
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Re: Do you think that would work for a led conversion?

#60 Post by MichaelG. » Sat Oct 30, 2021 3:50 pm

jfiresto wrote:
Sat Oct 30, 2021 3:40 pm
Not to mention that it will probably start wearing out within a few hundred adjustment cycles.
Quite so … [although you did mention it]

My post was just a convenient way of introducing people to the chip.

MichaelG.
Too many 'projects'

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