AO Illuminator - LED replacement?

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bralex
Posts: 86
Joined: Mon Jan 22, 2018 11:34 am
Location: Colorado, USA

AO Illuminator - LED replacement?

Post by bralex »

Good day all. I have an 1036A AO scope with a halogen bulb - I've seen it referenced as either 15 or 20W. It came without the power supply, so I was looking online for a suitable replacement - specs are 6.5W and 2A, easy enough to find for under $20. Is there any reason, besides some wire splicing, that something like this would not work?

https://www.amazon.com/Universal-Switch ... 213&sr=8-6

I've also been looking at possibly wiring in an LED instead, any special concerns there?

Cheers,
Scott

Pau
Site Admin
Posts: 5163
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

Hi Scott,

To drive an LED you need a constant current driver, not just a power source. For the microscope you want one dimmable and an LED with a size similar or a bit bigger than the lamp filament it replaces and ideally to place it at the very same position.

We can discuss it later, now I'm quitting home (the lockdown has been relaxed a bit here in Spain...)
Pau

bralex
Posts: 86
Joined: Mon Jan 22, 2018 11:34 am
Location: Colorado, USA

Post by bralex »

6-v power supply did nothing, so I suspect a bad bulb. The housing is almost exactly the size of the head of a Jansjo lamp, hmmmmm!

chris_ma
Posts: 252
Joined: Fri Mar 22, 2019 2:23 pm

Post by chris_ma »

if you have a voltage meter, then a bad bulb is easy to check:
nearly all of them have a resistor meter, if the halogen is burnt out it will show infinity, otherwise some other value.

LEDs has some advantages, you can easily get more brightness without generating a lot of heat, and you can also get less orange biased light.

downside is, the cheap ones don't have a good spectral color uniformity, meaning some colors can be distorted. you also need a power source with limits the current (or put a properly calculated resistor in series).
chris

bralex
Posts: 86
Joined: Mon Jan 22, 2018 11:34 am
Location: Colorado, USA

Post by bralex »

Voltmeter confirmed a dead bulb; I went ahead and sacrificed a Jansjo lamp for the cause; an ugly hack but it seems to work just fine! I had to file down the housing to fit - needed about 2 mm on both width and depth, the Jansjo could handle that with no problems. A few parts removed (bulb socket, flip cover), an o-ring to hold the stem of the Jansjo, some electrical tape (duct tape seemed like overkill).

I can't speak to the change in light quality as I never had a working AO power supply or bulb. As hack, it seems ok though!

One pic to show the ugliness!

Image

mawyatt
Posts: 2479
Joined: Thu Aug 22, 2013 6:54 pm
Location: Clearwater

Post by mawyatt »

bralex wrote:Voltmeter confirmed a dead bulb; I went ahead and sacrificed a Jansjo lamp for the cause; an ugly hack but it seems to work just fine! I had to file down the housing to fit - needed about 2 mm on both width and depth, the Jansjo could handle that with no problems. A few parts removed (bulb socket, flip cover), an o-ring to hold the stem of the Jansjo, some electrical tape (duct tape seemed like overkill).

I can't speak to the change in light quality as I never had a working AO power supply or bulb. As hack, it seems ok though!

One pic to show the ugliness!

Image
Hi Scott,

Nice rework!!

Might consider some additional mods to the Jansjo. Mine had a yellowish cast (2700K) and not too bright (220 lumens). Replaced the LED COB module with a higher power and 5000K COB and added a current mode controller that can be also used as a strobe.

Best,

https://www.photomacrography.net/forum/ ... ght=Jansjo
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

bralex
Posts: 86
Joined: Mon Jan 22, 2018 11:34 am
Location: Colorado, USA

Post by bralex »

Thanks, I was following your thread at the time too. Lighting is the next great task for me in my camera rig - this scope was just one I had around, I don't yet do much with it.

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