---
layout: post
title: "Building a COSMAC/RCA CDP1802 learning computer"
date: 2024-05-01 13:00:00 +0200
comments: true
categories:
---

# PCB making

## Printing the transfer

I tried several methods to prepare the toner transfer intermediate:
* baking parchment paper with double sided tape
* glossy magazine with scotch tape
* glossy magazine with glue

What seemed to work best is the glossy magazine glued to a sheet of paper strong enough to not have irregularities.
:warning: Don't forget to mirror the image before printing :facepalm:

## Preparing the board

Grain #500 sandpaper -> steel wool -> acetone

## Transferring the toner

* **1st attempt** (glossy paper taped to carrying paper, max heat, 1.5 min): **failure** the paper sticks to the PCB, no transfer
* **2nd attempt** (parchment paper glued to carrying paper outside of printing zone, max heat, 3 min moving across surface, let cool): much better, good enough for silkscreen but probably not for etching
* **3rd attempt** (glossy paper glued, pre-scrubbed with isopropanol):
  * very good print, almost no defects
  * transfer with acteone/alcool (3:8): total failure, did not stick to copper at all.
* parchment paper, taped to carrying paper on all sides (outside of printing zone), pre-cleaned with isoprop
  * iron 2 min on each part of the surface, temp setting 2, lots and lots of pressure
  * let cool completely
  * transfer failed :-(

Looking for a laminator...