Build your own Games Machine
By Matthew Preston
We never had a video
game at home, but I remember playing Pong and Breakout
at an after school club. I also remember putting
coin after coin of my pocket money into a machine with
a big yellow PacMan painted on the side. Those days
are now gone, but we can recreate those memories by
building our very own games machine that will plug into
most television sets or video recorders.
I recently came across
such a kit quite by accident whilst browsing the latest
Maplin Electronics catalogue. The Velleman kit entitled,
"Classic TV Tennis Game", caught my eye as
there was a small picture next to it which reminded
me of Pong. At only ten pounds, I thought it was worth
a go. A week or so later I purchased the kit from a
local store and set about building it.
I have built Velleman
kits before and know from experience that they generally
go together quite easily and have practically everything
you need in the box. I have quite a bit of experience
with amateur electronics and came across a number of
stages that could potentially confuse the inexperienced
builder. What follows is an account of how I went about
building my kit and the pitfalls I encountered (which
will hopefully enhance the documentation that comes
with the kit should you decide to build your own).
Before I begin, I would
like to say that although the finished product is of
excellent quality, it is not really a toy and should
be treated as part of your computer collection. As a
result, it's not something for the children to bash
To assemble the kit,
I you will need the following:
- Soldering iron
18-24 watt is enough with a small to medium sized
with the flux inside it is recommended. Try to make
sure that you get the thinnest solder as possible
(I use 0.7mm which should last you ages if you get
a small reel of it).
- Solder station or
stand with a damp sponge.
- A comfortable place
to work with good lighting.
- Small pair of side-cutters.
- Cross-head screwdriver.
- Magnifying glass.
- Three AA batteries.
- Patience, lots of
When you buy the kit
you may wonder where the circuit-board is - I did. For
some reason, it is hidden inside the packaging, along
with the main instructions (so don't throw anything
away). Before you begin, check that you have everything
you need by looking through the instructions and familiarise
yourself with all of the components. If you are new
to building kits, Velleman have printed the best practice
for soldering at the top of the instructions, however,
I would recommend practicing before building your kit.
This is exactly
what you get
Building the kit
Begin by warming
up the soldering iron, tin the tip by applying a little
solder to the hot tip and wiping it gently across the
damp sponge. You will need good eyes, I use a magnifying
glass to check components as they are generally too
small to read properly. Starting at stage one look down
the list of resistors and solder each one to the circuit
board in turn. I find it easiest to only take them
from the strips as needed so as not to mix the components
The resistors in place.
Stage two, the diodes. Don't
be mislead by the diagram, the first one is tiny, it
also looks a bit like the Zener diodes in the next stage. To
identify the required diode, take your magnifying glass
and look very carefully at what is printed on them and
how they are constructed. There is only one diode with
the number 1N4148 and it is cylindrical in shape with
a black bar at one end, quite different from the Zener
diodes that look a bit like grains of rice with a silver
crack in the middle. Make sure the black bar on the
diode matches the white mark D1 on the circuit-board
and solder it in place. The second diode D2 is huge
by comparison and is quite easy to identify. This
time however, the silver bar marks the polarity.
Stage three, the Zener
diodes. These are very small and there are four of them. Making
sure that you observe which way round they go on the
board and solder them in place.
Stage four, the IC socket. This
can be a tricky one if you have not soldered one before,
as you must be quick with the iron or you will melt
the socket. Making sure the notch on the socket matches
the picture on the board and put the IC socket in place.
Holding the socket turn the board over and place it
flat on the bench. The socket should now be held firmly
with the pins sticking out the copper side of the board.
Start by soldering alternate pins on the socket and
complete the four corners, this will hold the socket
in place. Carefully complete soldering the rest
of the pins and then use your magnifying glass to check
that you have not accidentally made a solder bridge
between any of the pins.
The microprocessor is
marked 121PAL and is copyrighted to Velleman. The component
used is a Programmable IC, or PIC, number PIC16C505.
They are quite robust but basic static precautions should
be taken. The fascinating thing is that the IC has no
real independent function, just inputs and outputs,
the entire game, video and sound output is generated
by the chip with pre-programmed software, amazing stuff.
Bend the legs in a little and place it gently into the
holder. When you are sure that all the legs are correctly
placed, push the IC home.
Stage five, push buttons.
These are quite simple to push in place. Once you have
done this, solder the legs to the board.
Stage six, quartz crystal
(this can be a little tricky). Push the long legs through
the board leaving enough to lay the crystal flat. Bend
out these legs slightly, this will stop the crystal
from falling out of the board as you try to solder it
to the circuit. Solder the small wire across the crystal
as shown in the diagram to keep the crystal from moving.
Stage seven, trim/potentionmeter.
Push into place and bend the legs over on the copper
side of the board, this will hold it firmly as you solder
Stage eight, capacitors. C1
and C2 have the number 18 printed on them, there is
no polarity to observe just solder them to the board.
Stage nine, electrolytic
capacitors. The instructions indicate that they should
be lay flat on the circuit, I found it easier to poke
them through the board and bend out the pins so as to
make them less awkward to solder. The polarity on these
is very important, luckily they have the negative symbol
printed quite large down one side, no chance of making
a mistake here.
Stage ten, LED. Take
a close look at the instructions, you want the shortest
leg nearest the LD1 label.
Stage eleven. There are
a couple of nice gold-plated sockets here, Push them
in place, you want the outer most holes or they will
keep falling out. Apply enough solder to the legs to
hold them, don't flood the board with it.
The build is almost complete,
Stage twelve is a bit of a pain, mainly due to me having
two left arms and being all thumbs. The exploded diagram
gives the best idea, stick with it, it is very awkward
to get the battery compartment to screw together properly.
Your completed board
should look like this;
The completed kit.
Playing the game
You will need
two phono leads to connect both the video and audio
to a television. Also depending on the TV you may also
need a Scart adapter, I have used the video inputs at
the front of my video recorder next to my PC. The kit
produces what is known as composite video output. Most
new video recorders have this as standard, so if you
have an old television this should not matter. With
the television now on, put three AA size batteries into
the holder on the kit. The circuit should burst into
life, with a red glow from the LED. Don't be alarmed
it the screen rolls, just press and release the reset
button on the kit (don't expect colour, this is retro
gaming). If you like, you can adjust RV1 marked brightness
for a brighter picture, don't over do it or the screen
may become unstable. For single playing, hold the left-up
button and press then release the reset button. Push
both up/down buttons to start and BIP! BIP! we're away.
A screen-shot of the game as it will look on your television.
To give you an idea of
just how small the completed kit is, below is a photograph
of my home system.
I am a great fan of Atari
and would love an original Pong machine. Sadly this
is probably the closest I am likely to get, but for
a tenner, it was great fun to build and is a joy to
If you are
interested in building your
own kit and live in the
UK, the Classic TV Tennis
Game kit can be purchased
from Maplin (stock no. QP59P).
If you are interested
in building your own kit
and live in Germany, the
Classic TV Tennis Game kit
can be purchased from Conrad
(stock no. 130374 - 62).
Thanks to reader, Sebastian
Kraus, for letting us know.