Re (2): Voltage halver.

Roger Hayter <roger@hayter.org> wrote:

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"?

Certainly adjustment while looking down the scope must be convenient.

Input voltage is another factor I should have mentioned. The scope is
going to Africa where the wall socket will probably be 220 V. The 3-12 V
adapter I have accepts 110-240 V input.  Good.

6 V is roughly the bottom 1/8 th of the range of the adapter.  Halving
the output with efficient switching would allow use of the full range
of adjustment.

I was hoping someone would cite a voltage halver as simple as this.
https://www.ebay.ca/itm/404142157480

Soldering leads to an IC would be a reasonable 2nd possibility.

Thx,                                ... P.