How to amplify 3.3v servo signal to 5v, tiny amplifier construction welcome.

What would be the smallest, most space-efficient circuit that could do that ?

Reason; some servos pick up a lot of noise (and shake) when using 3.3v over a meter servo cable. - I also added 20uF capactitor on the power near the servo, that reduced the problem a little, not much.

Use a comparator .

(to make things easy, go for a "rail to rail" type).

If you need to drive lots of servos then a CD4050 might be better.

With some luck , I even have a HEF4050 around, but I hoped to make the amp very tiny, integrated between an male and female connector and drowned in epoxy. That would make it easy to use it on only the lines of the affected servos.

AndreK: but I hoped to make the amp very tiny, integrated between an male and female connector and drowned in epoxy. That would make it easy to use it on only the lines of the affected servos.

You can get comparators in SOT23 packages...

Why not just use a N-MOSfet (BSS138, or so) as a low side switch?

thank you both, will try both solutions (for tiny circuit, and both source/sink with 4050)