Electron Workshop

By Marc Harris

Originally published in EUG #02

Introduction

Hello and welcome to the first Electron Workshop! In this series we will be looking at how to create your own hardware add-ons. In later workshops we will be seeing how to make full use of your Rombox and Plus 1 but for now all you need is your good old Acorn Electron computer.

Break Key Disabling

How often have you pressed the BREAK key in the middle of a program? I've done it quite a lot. It's annoying and valuable data could be lost. As this is the first workshop, we will give two solutions (both from old editions of Electron User - may it rest in peace!). Only one of them will require soldering skills, but in future workshops this will become more and more necessary.

Firsrtly, I give you Dan Eden's Anti-BREAK system:

Method 1: Anti-Break System

Advantages

  1. Fairly easy to make
  2. No soldering required
  3. Will not cause interference with system
  4. Cheap to make

Disadvantages

  1. Looks tacky
  2. Can be knocked to the floor and trodden on

How To Make It

Cut a piece of aluminium (0.5mm) to the dimensions in figure I, score along the dotted lines and carefully bend. Smooth the edges with emery cloth and slide it over the BREAK key as in figure II.

To use the BREAK key again, simply slide the ABS out of the way. Yes, it really is that simple!

Method 2: Break On/Off Switch

Next, we have Peter Julian's BREAK On-Off switch.

Advantages

  1. Quite easy to make
  2. Only limited soldering skills required
  3. Cheap to make
  4. Looks professional
  5. Cannot be broken easily

Disadvantages
  1. Some soldering skills necessary
  2. If BREAK key is turned off when the computer is first switched on, then the Elk will 'Hang up'. To reverse this effect, simply turn the key on and press it. This will not cause damage to the computer
  3. Incorrect installation can cause expensive damage!

How To Make It

First, undo the four screws on the bottom of the Electron (if it is not under any service guarantee) and gently ease the keyboard connecting cable from the row of pins on the main circuit board so that the keyboard can be taken off for easier access and closer examination.

All that needs to be done is for a deep cut to be made in the track on the circuit board that leads to the BREAK key as shown in figure III. Next, a two position double-pole slide switch is fitted (See Figure IV).

Accurately mark out where the slot and fixing holes will go. Drill carefully two holes at the ends of where the slots will go. Use a small file to enlarge and square the holes until the slot is the correct size. The fixing holes should then be drilled and countersunk with a large drill bit. This is best done by hand as even using a hand drill it is quite easy to go straight through the plastic, making a hole which is much too big.

Finally, a 3mm hole is drilled next to the BREAK key to take a 3mm light emitting diode. This draws power from the keyboard and dims/goes off when the BREAK key works and lights up when the BREAK key is switched off.

The circuit diagram is shown in figure V, and figure III shows where and how the switch and LED are wired to the keyboard. Figure VI shows the point under the protective pad where the power is taken for the LED. The insulating pad has to be pulled back to reveal the connection, and for safety a thin piece of card must be taped over the exposed circuit board once the wire is soldered in place.

Components

Both of the above are good ideas but if you can think of a hardware project that's as good or better for the workshop to consider, please contact EUG! The components for the BREAK switch can be obtained from any good electronics supplier.

Disclaimer

Please note that you undertake any hardware project at your own risk and we cannot accept responsibility for any damage, loss or injury which may occur.

Next Time

Next time we'll be looking at some basic electronics and alter we'll make a multi-purpose user port, with which we can interface with such things as 'buggies', robot arms and other computers. Finally, could some kind soul lend me a Rombox manual for a few days please?

Marc Harris, EUG #2