Reducing voltage of laptop power supply

On Tue, 18 Apr 2023 10:34:53 -0000 (UTC), Jasen Betts
<usenet@revmaps.no-ip.org> wrote:

>On 2023-04-16, Clive Arthur <clive@nowaytoday.co.uk> wrote:
>> On 14/04/2023 14:59, Lamont Cranston wrote:
>>> I have a Toshiba 3.4A, 19V laptop power supply that I want to reduce to 12V.
>>> Is it as simple as finding a 19V zener and changing it to a 12v zener?
>>>                  Thanks, Mikek
>>
>> Given that 19V is a *very* common laptop supply voltage, I wouldn't be 
>> surprised if they used a fixed 19V supply chip.
>
>with a built in opto-isolator?

Some flyback controllers sense the flyback voltage and don't have the
optocoupler. Saves money and is usually good enough for a wall wart.

I'm trying to keep everything food grade. So, the buckets that were food buckets. The heaters are, not food grade are kept from the water, so should not contaminate. I laid some thin copper tape, put the heater on and covered it with another piece of copper tape. I offset the twp pieces of tape to get more area, but I'm not happy with the heater reaching 147*F. I think I may need more heaters (or a different type) to get the required Wattage but a lower temperature.
 My original plan was to use a 5 gallon bucket and foam in a 3.5 gallon bucket for insulation, but I decided against it as, I didn't see a way, to keep it food safe. Actually, now that I have the two buckets that seem to be a good solution, I could put this all in a foam insulated 5 gallon bucket. Maybe something for the future development.
                        Mikek