A quick review of a 3V-12V 5A powersupply

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DrPhoxinus
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A quick review of a 3V-12V 5A powersupply

#1 Post by DrPhoxinus » Sun Mar 14, 2021 9:00 pm

I was intrigued when I saw this type of power adapter in another post

https://www.ebay.com/itm/Adjustable-AC- ... SwNeFeV3eX

It was $13.55 plus $2.99 shipping, and it came from China in 2 weeks.

According to my wife, I have 13 scopes (I don't think she saw all of them).

They vary in requirements. Some are the old AO with those pins, some are Leitz, one one Leitz has pins separated that it doesn't fit a Leica power supply. Some are 6 volt incandescent, 6 volt halogen, 12 volt LED, 12 volt halogen.

So an adjustable supply would fit the bill.

I bought these for connectors
https://www.amazon.com/Pigtail-Connecto ... 818&sr=8-6


but I should have bought these as the wires are 18 gauge and the others look maybe 24 AWG. I worry about running up to 5 amps through those.

https://www.amazon.com/dp/B08SYM9KZ7/re ... ljaz10cnVl

The supply fits these connectors, 5.5 mm x 2.1 mm.
The display reads down to 1/10 of a volt. Checking it with a multi-meter it was pretty much right on, maybe a tenth or so off at some voltages.

Surprisingly, the center pin on the supply is negative, not positive like most supplies, so this needs to be taken into account with LEDs.

Gerard

MichaelG.
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Location: NorthWest England

Re: A quick review of a 3V-12V 5A powersupply

#2 Post by MichaelG. » Sun Mar 14, 2021 9:07 pm

I think you are right to be concerned about the AWG sizes
:geek:

https://meters.co.uk/american-wire-gaug ... tor-sizes/

MichaelG.
Too many 'projects'

DrPhoxinus
Posts: 128
Joined: Mon Jan 28, 2019 5:17 pm
Location: Rochester Hills, MI

Re: A quick review of a 3V-12V 5A powersupply

#3 Post by DrPhoxinus » Sun Mar 14, 2021 10:34 pm

Yes,

I ordered a new set of connectors with 18AWG wire.

The voltage adjustment is not linear.

6 volts is about 9 o’clock, 12 volts about 12 o’clock and turning it further doesn’t change voltage

PeteM
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Re: A quick review of a 3V-12V 5A powersupply

#4 Post by PeteM » Mon Mar 15, 2021 6:01 am

Just to add on this power supply, it is small enough that it can often be stuffed into the base or the upright of a microscope with a failed power supply. As an example, I fit one into a Leica DMLS. Popping it out of the case, if suitably protected, might also allow better cooling.

In addition, it's was possible in this case to disconnect the potentiometer and re-connect wires from the stand's own potentiometer. You'd want to check the resistance across both pots before doing so, but my recollection on the Leica is that they were nearly the same - something like 5K or 10k ohms each.

MicroBob
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Re: A quick review of a 3V-12V 5A powersupply

#5 Post by MicroBob » Mon Mar 15, 2021 6:48 am

Hi together,
these are really interestinng power supplies. I use on to power a fan to remove unfriendly gasses im make while curing Pleurax. It is a 12V version and the potentiometer works nicely over the whole range.

It would be interesting to use them to power an LED. Cree XHP35 and 50 LEDs come in 6V and 12V versions. What I don't know is how to make an illumination from this that can be regulated nicely from 0 to full power. Any Ideas? And have you checked whether they supply continuous power or are ther PWM gaps, problematic for photography?

Bob

DrPhoxinus
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Re: A quick review of a 3V-12V 5A powersupply

#6 Post by DrPhoxinus » Mon Mar 15, 2021 9:57 pm

Bob,

My pot is not linear. Maybe the substituted a pot with a different value or taper.

How long have you had yours?

Gerard

DrPhoxinus
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Re: A quick review of a 3V-12V 5A powersupply

#7 Post by DrPhoxinus » Wed Mar 24, 2021 6:52 pm

Here is an update on the power supply.
The first one I ordered from ebay and it shipped from Hong Kong.
My pot was not linear and it went to 12.5 at the 12 oclock position

Then I saw the same model at Amazon!

https://www.amazon.com/YUNBO-Adapter-Vo ... ces&sr=1-1

It was Prime and came in 2 days. Both units have the same model number KLY-120500 yet the second unit's pot is much more linear.

There is an interesting range of reviews on Amazon. Some complained of the non-linearity of the pot like my first unit, but overall the tone is quite positive with one reviewer loving it for powering his microscope LEDs.

So like other things from China there may be quality control issues, but for the money it is pretty cool.

Gerard

DrPhoxinus
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Re: A quick review of a 3V-12V 5A powersupply

#8 Post by DrPhoxinus » Mon Mar 29, 2021 9:38 pm

Earlier I said the center pin was negative. This is my error because of polarity at the meter.

The center pin is positive as with most supplies.

Also I found that this common LED dimmer rated 12 to 24 volts

https://www.ebay.com/itm/12V-24V-8A-Swi ... Swc~tbRbnH

will function if fed 6 Volts DC

Gerard

Voyager-1
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Re: A quick review of a 3V-12V 5A powersupply

#9 Post by Voyager-1 » Thu Apr 15, 2021 2:51 pm

DrPhoxinus,

Thanks for the info! Have been purchasing the 50 year old transformers for the AO microscopes and it is hit or miss if they work.
One of power supplies you listed will serve about 7 different power ranges on my microscopes!
Have also been trying to switch out the high wattage lamps to the LEDs (have ordered a few car taillight LEDs, which have a flat
surface, not like the corncob LEDs).
If all goes well will post results.
Thanks again!

V

dtsh
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Joined: Wed May 01, 2019 6:06 pm

Re: A quick review of a 3V-12V 5A powersupply

#10 Post by dtsh » Thu Apr 15, 2021 3:54 pm

Voyager-1 wrote:
Thu Apr 15, 2021 2:51 pm
DrPhoxinus,

Thanks for the info! Have been purchasing the 50 year old transformers for the AO microscopes and it is hit or miss if they work.
One of power supplies you listed will serve about 7 different power ranges on my microscopes!
Have also been trying to switch out the high wattage lamps to the LEDs (have ordered a few car taillight LEDs, which have a flat
surface, not like the corncob LEDs).
If all goes well will post results.
Thanks again!

V
I have a parts list I used for an AO10 if that might help. I took a more expensive route with a potentiometer controlled driver and LED, parts were something like $25 or so. I don't really think the adjustability is necessary though, the ND filter largely works as well.

BramHuntingNematodes
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Re: A quick review of a 3V-12V 5A powersupply

#11 Post by BramHuntingNematodes » Thu Apr 15, 2021 4:19 pm

Linear tapers for switching to different systems might make sense, but logarithmic taper is better for voltage controlled dimming as subjectively people interpret log changes in flux as linear changes in "brightness"
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

DrPhoxinus
Posts: 128
Joined: Mon Jan 28, 2019 5:17 pm
Location: Rochester Hills, MI

Re: A quick review of a 3V-12V 5A powersupply

#12 Post by DrPhoxinus » Wed Apr 28, 2021 9:31 pm

I would be interested in your parts list.
Besides the AOs I have two Ortholux I that have missing illumination systems

Gerard

dtsh
Posts: 310
Joined: Wed May 01, 2019 6:06 pm

Re: A quick review of a 3V-12V 5A powersupply

#13 Post by dtsh » Thu Apr 29, 2021 3:17 am

DrPhoxinus wrote:
Wed Apr 28, 2021 9:31 pm
I would be interested in your parts list.
Besides the AOs I have two Ortholux I that have missing illumination systems

Gerard
In case my parts list is of value, this is what I used. Not included is a resistor, I think 15k? and a 10k potentiometer. If there's an interest in the schematic I can make a copy of it, but there isn't much to it.

LED substrate:
https://www.mouser.com/ProductDetail/be ... cycode=USD

Cree LED
https://www.mouser.com/ProductDetail/cr ... cycode=USD

LED Driver (0-10v dimmer)
https://www.digikey.com/en/products/det ... 00/2720720

It definitely needs a good heatsink as I cooked one of the LEDs with about 2 hours of use. My guess is there was too much thermal adhesive and not enough direct metal to metal contact.


I have little doubt one could make something cheaper and better as I'm not very skilled in electronics.

DrPhoxinus
Posts: 128
Joined: Mon Jan 28, 2019 5:17 pm
Location: Rochester Hills, MI

Re: A quick review of a 3V-12V 5A powersupply

#14 Post by DrPhoxinus » Thu Apr 29, 2021 11:53 am

I would be interested in seeing the schematic.
There may be some engineers that could comment on it.

Thanks

Gerard

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