6 V variable power supply for illumination in Zeiss microscope.

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:

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

John :-#)#

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:

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.

... but the adapter is missing.

... and a replacement is wanted

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

)

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.

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:

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

Peter Wieck Melrose Park, PA

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

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

......... Phil