Design and produce a digital signal amplifier

Job ID: 31191301

Budget: $25 – $50 CAD

I am looking for a freelancer that could help me design and assemble digital signal amplifier (DSA). Mostly for TTL signaling.
I already have a design and some production made, but I need to scale up the production and need some support for further enhancement of the device.
Attached is the current user's documentation of the DSA.
Production need is about 20 to 50 devices per year.