Re: Voltage halver.

On 3 Apr 2024 at 21:40:27 BST, "Roger Hayter" <roger@hayter.org> wrote:

On 3 Apr 2024 at 21:29:19 BST, "Liz Tuddenham" <Liz Tuddenham> wrote:
 

<peter@easthope.ca> wrote:
 

A variable power adapter is required to drive a 6 V, 30 W incandescent
bulb in a microscope.
 
Similar to the 3-12 V 5 A adapter here.
https://www.ebay.ca/itm/305207182573
An adapter providing 1.5-6 V output would be better but I haven't
found one.
 
Rather than limit the adjustment to 6 V, I think of halving the
output.  An integrated circuit in a 4 port package is conceivable.
https://www.youtube.com/watch?v=VJfqBQ2ybpk
 
Does the marketplace offer a solution?
Another idea?

 
A 6v transformer and an adjustable resistor made from an old electric
fire bar and two jubilee clips?

 
I thought of that, but it is not very useful to adjust while looking down the
microscope and I wondered if AC might affect microphotography.  Have you seen
the price of 30W WW pots or "rheostats"?

Also, an electric fire element is going to be about 30ohms in North America,
and since you want fractions of 2ohms adjustment over 1 to 3 turns is going to
be somewhat fiddly.

--
Roger Hayter