gunrunnerjohn posted:Stan, your problem is you don't have a couple of these for those trimmers.
Au contraire mon ami. Pardon my French. 
I see you suggest the Spectrol version which runs $3.93 at DigiKey. You can get the Bourns version for $1.61. With the $2.32 I just saved you, you can buy half a dozen more of those 38 cent DC-to-DC regulators! That's my good deed for the day and it's still morning! Plus, the Bourns version is in blue which matches the color of the trimmers. Color coordination is very important for the circuit to work properly. 
Caterpillar yellow, John Deere green, Bourns blue... 
Seriously though, in some cases these regulator modules might be upside down under the layout/table/bench and it can be a pain to fuss with an adjustment tool. Much easier to use a long knob trimmer and your built-in tool (a.k.a. your finger) to adjust. 
