ΔStop 100 Timer PCB

Do you want to build your own ΔStop 100? Then you can just order the PCB that powers the tool! This includes:

• A professionally manufactured PCB
• All components soldered
• Fully tested
• Microcontroller flashed with ΔStop 100 firmware

You will need to separately provide the housing, knob hardware, power supply (5VDC 1A), and an appropriate external relay to activate your enlarger. (Such as this)

ΔStop 100 is a dedicated enlarger timer that uses logarithmic, f-stop based timing instead of linear seconds. You set a base exposure in stops and every click changes exposure by a fixed fraction of a stop, so the math stays the same no matter the print size or paper type. That means faster test strips, clearer intent with every change, and less guesswork when a print needs a tiny nudge instead of a full second.

It behaves the way photographers already think: exposure as stops, not time. The interface is focused on repeatable decisions, so you can move from test to final with confidence and keep a consistent record of the choices that got you there.