6 V variable power supply for illumination in Zeiss microscope.

[pe...@easthope.ca]

Hi,

The supply in this photo powers an incandescent bulb of a Zeiss
microscpe. http://easthope.ca/ZeissLampSupplyLPS7.5.jpg

That supply accepts 110 V input. The bulb is marked 6 V 15 W. For
several decades, the 'scope was commoplace in North America. Likely a
similar supply accepting 220 V input was common outside North
America.

I want to find a power adapter which accepts 220 V input. eBay has
this and similar listings. https://www.ebay.ca/itm/185935059631

If the output connection is compatible with the plug on the lamp cord,
the supply should work but the total price is approximately 670
Canadian dollars. =8~/ Rather pricey to power a small bulb.

A simple alternative is a 6 V brick adapter and potentiometer.

Other ideas?

Thanks, ... Peter E.

[John Robertson]

Simple to make a PWM (Pulse Width Modulation) power supply for 6VDC at a
few amps. Cost well under $100 with enclosure.

You need a pot that handles at least 15W, preferably 25 to 50W to avoid
overheating.

Something like this, but it would draw 1/2A if wired across the 6VDC supply:

https://flippers.com/catalog_oc/bat-power-potentiometer-5a-6202

Or if you can find a 24 to 50 ohm 50W potentiometer/rheostat.

John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
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#7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
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[Jeff Layman]

I assume you don't have the 110V power supply (or you do have it and it
doesn't work) as then the simplest solution would be a 220V - 110V
transformer. If you don't have the supply, can you get a connector for
the microscope power supply, or would you have to modify the wiring?

Anything here cheaper and suitable:
<https://picclick.com/Popular/zeiss-power-supply>

--

Jeff

[John Keiser]

Temu [usually ships quickly fron US] or AliExpress [ships slow from
China] has low volatage PWM motor controls for only a few dollars that
you could adapt.

[whit3rd]

On Sunday, September 10, 2023 at 10:55:47 AM UTC-7, pe...@easthope.ca wrote:
> Hi,
>
> The supply in this photo powers an incandescent bulb of a Zeiss
> microscpe. http://easthope.ca/ZeissLampSupplyLPS7.5.jpg
>
> That supply accepts 110 V input. The bulb is marked 6 V 15 W.

... but the adapter is missing.

[whit3rd]

On Sunday, September 10, 2023 at 10:55:47 AM UTC-7, pe...@easthope.ca wrote:

> Hi,
>
> The supply in this photo powers an incandescent bulb of a Zeiss
> microscpe. http://easthope.ca/ZeissLampSupplyLPS7.5.jpg

... and a replacement is wanted

> A simple alternative is a 6 V brick adapter and potentiometer.
>
> Other ideas?

The simple idea is expensive, if the potentiometer has to handle
the 15W power requirement.

A cheap alternative is a suitable power brick (old laptop power supply, 19V/3A being
a common rating) for plugging into the wall socket, and a switchmode
buck regulator (LM2596 is a keyword to try, or
<https://www.temu.com/dc-4-40v-8a-voltage-regulator-module-xh-m404-pwm-adjustabl-dc-dc-step-down-voltage-regulator-dc-xl4016e1-digital-display-g-601099513527641.html> )

You'll want to add a fixed resistor to the potentiometer output control, so it only goes zero-to-6V; that
bulb is likely to be a hard-to-replace item. Testing with an old auto headlamp bulb would be my recommendation.

[Peter W.]

You know.... A few rechargeable batteries and/or a small train transformer would do nicely. Filaments don't care whether they are seeing AC or DC, by the way, so even a small 6V bell transformer would do nicely. Adding a dimming control would be a simple few-watt pot.

Or: https://www.amazon.com/6V-Power-Supply-COOLM-Transformer/dp/B08BCBZ632/ref=sr_1_4?hvadid=616991248310&th=1

I am constantly reminded that this venue exists to find the most complicated solution to the simplest problem.

Peter Wieck
Melrose Park, PA

[legg]

On Mon, 11 Sep 2023 14:47:28 GMT, "John Keiser" <johnk...@juno.com>
wrote:

Keep in mind that these usually PWM the negative terminal without
filtering. Lack of filtering won't affect lamp, but sq wave on neg
terminal could present an interconnection issue, if the lamp assembly
assumes a chassis ground connection on the that terminal.

For long leads, it also presents a source of EMI in the immediate
viscinity that is not easily identified, unless you're intimately
familiar with the hardware.

RL

[Phil Allison]

Peter W. wrote:
------------------------
>
> Or: https://www.amazon.com/6V-Power-Supply-COOLM-Transformer/dp/B08BCBZ632/ref=sr_1_4?hvadid=616991248310&th=1
>

** SMPS's like the above may be incompatible with an incandescent lamp load as used in the op's microscope.
When starting up from cold, the filament wire presents a near short to the supply so it may shut down to protect itself - see the third point in the list of features.
A supply that can deliver 3A or so into a short will be OK, as expected with a linear DC regulator or a simple 6VAC transformer.

> I am constantly reminded that this venue exists to find the most complicated solution to the simplest problem.

** Just get posters to stop presenting us with complex problems while wanting a simple & cheap solution.


......... Phil