Board Design

A project log for PolyMorph Receiver

A minimalist direct conversion radio receiver. 4 general purpose transistors and a Polyakov 2 diode mixer.

morphmorph 05/08/2020 at 17:240 Comments

Since I ordered my small kit CNC machine after I saw a blog post about it on Hackaday I've been fine tuning my rapid prototyping techniques. Above is the machined PolyMorph receiver pcb board. Currently I'm experimenting with the muppet style construction with my own twist; I keep everything very close and squarey.

I start the design process on Inkscape. In the document properties I set the grid size to 2.54 by 2.54 mm, major lines every 4. I then make adjacent squares of 5.08 mm depending on what I want to lay on the board. For example on the far left of the pcb image there is a tetris T shape, that's for the base of a common emitter RF amp. The top long strip is the vcc. 

Next, I open up JSCut in my browser, load the svg from Inkscape and generate some Gcode. Then it's time for Chilipeppr, still on the browser. Finally, voila a machined pcb!

I've made quite a lot of boards this way. I love the speed of it once you get the knack of it. I think of a design and in 30 minutes I'm soldering components onto the board. One big advantage of this unorthodox method is that I can mostly fix any mistakes by extending the through hole components to where they need to go and split squares by hand, or a blade... my hands are not that sharp :D

In the next update I will post some pictures of some scavenged components on the board and some component trickery. There'll some tips on how to get some serious 'pff' out of standard varactor diodes as varicaps and a relief for those of you who either don't have ferrite toroids on hand or would like to know another method of notorious e-imp-matching-dance courtship practice.