I have a bunch of resistors 10k 5W.
Connected to 230V AC line that is a pretty good heater of 5W.
So 6 of them between 2 Aluminium sheets to become a 30W Heater for my chili seed boxes.
The little corns need 28°C. I will build 3 heaters now.
one month later the little chilis can go out in the room for normal temperature, when they have 4 libs.
Test gear: John Fluke, 2190A with K Type sensor.
I have some chili from india, spicy,
some from thailand, hot,
Jalapeno from mexico, spicy,
and the Trinidad Moruga Scorpion Chili, skull, 2 mill. scovilles
baby water melones, some cocktailtomatoes...
all to seed now. The climatic change provides some hot things in the garden