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Constructional Project
Background image: https://unsplash.com/photos/gaming-room-with-arcade-machines-m3hn2Kn5Bns
Skill Tester 9000
Part 2 – by Phil Prosser
This retro game is a fun and educational
project to create a dexterity-based game with nine
diffiiculty levels, a health bar graph, a timer and four
diff
different sound effects. It is based mainly on 4000-series logic
and all through-hole parts on a single circuit board.
T
here are some sections of this
game that advanced constructors
can customise, such as changing
the winning and losing tunes, but we
will describe the assembly process for
the standard version. There is definitely
scope for customisation when you make
the wire ‘obstacle course’, as you can
make it as easy or as hard as you want!
The assembly instructions will be
given in seven discrete steps. After
adding the parts for each step, you will
have new functions to test, so you can
pick up any problems early on and fix
them before tracking them down will
be more difficult.
You shouldn’t need any special tools;
a soldering iron, solder, fume extractor
and a multimeter for testing should be
all that’s required.
Construction
We will build the Skill Tester 9000
section by section and test each as we
go along. This allows people to work
with young constructors or students
in simple sessions, achieving visible
progress in each. Even as an experienced constructor, I build projects in
64
bite-sized chunks as it makes debugging simpler and there are built-in
coffee breaks.
The Skill Tester is built on a double-
sided PCB coded 08101241 that measures 174 × 177mm. During construction, refer to the PCB overlay diagram
(Fig.5) and Photo 1 to see which components go where and how they are
orientated.
Here are general cautions and instructions you should keep in mind
during the construction process:
• Ensure all diodes are fitted the
right way around (stripe to the right
or down on this PCB).
• All LED cathodes are upwards;
LEDs have a chamfer (flat edge) on the
cathode side.
• All ICs are installed with pin 1 to
the right. If you get one backwards and
are not using sockets, you will have to
cut all pins off using side cutters and
pull individual pins out (unless you
have a hot air rework station).
• Check the supply rail voltage every
time you power it up after adding parts.
We have included a ground test point,
with a 9V test point close by (below
IC1). You should measure more than
8V between the two with a fresh battery. If not, something is wrong.
• If something is wrong and, while
you are investigating, the noise from
the speaker is slowly driving you
insane, put a 1kW resistor in series
with the speaker to tone things down
a bit.
• Standard checks as you solder:
are there any solder blobs shorting
pins? Is each solder joint shiny with
the right shape? Has the solder adhered to both the component lead and
the PCB pad?
• For each polarised part, check
before and after soldering that it is the
right way around. Also check the part
numbers of ICs and double-check the
orientation before you solder them.
• If you need to check clock signals
and don’t have an oscilloscope, put
your DVM on its AC setting and probe
the test point. You should measure a
few volts AC or see pulses in the reading for very slow clocks.
Touch, Win & Reset sections
1. Let’s start construction with the
Practical Electronics | June | 2025
100nF
10kW
D18
4148
D21
D44
4148
4148
D23
4148
4148
D47
4148
D48
10kW
4148
D43
680kW
220kW
10kW
220kW
4148
D46
470kW
10mF
100nF
470kW
D45
4148
120kW
120kW
120kW
220kW
220kW
220kW
270kW
680kW
100nF
D29
4148
D32
D33
4148
4148
D35
D34
4148
4148
D37
D36
4148
4148
D38
4148
270kW
100nF
10nF
10kW
4148
D41
D42
4148
4148
270kW
IC14
NE555
1kW
10kW
1kW
100kW
100nF
10kW
100nF
10mF
IC15 4093B
100nF
100nF
10kW
24kW
22kW
27kW
24kW
24kW
24kW
27kW
18kW
18kW
18kW
IC13 4017B
D53
270kW
10kW
1kW
56kW
330nF
100nF
100nF
IC9
NE555
10mF
1mF
100nF
100nF
D17
D16
4148
4148
D19
D20
4148
4148
D22
D24
4148
D25
4148
4148
D27
10kW
D26
4148
4148
D10
IC88 44001177BB
IC
4148
4148
D28
1kW
D11
4148
4148
47nF
100nF
4148
D14
IC12 4013B
330nF
D8
IC11
LM386N
10mF
56kW
CON4
56kW
+
1kW
1kW
1kW
1kW
1kW
1kW
1kW
1kW
100nF
10kW
D55
4148
4148 D49
10kW
D39
D40
D52
4148
D30
4148
4148
D31
4148
10kW
10kW
4148
220mF
100nF
D13
D3
1kW
470mF
10W
IC7 4013B
100nF
4148
4148
SPEAKER
CON6
GROUND
+
D5
10kW
100kW
100nF
IC4 4013B
56kW
4148
CON3
4148
CON1
9V BATTERY
HOLDER
+
470nF
D1
100nF
IC6
NE555
IC1 CD4026B
100nF
LED11
RESET
100nF
D56
1mF
4148
Reduce
to make
harder
10mF 10mF 22mF
DP
9V
IC5 4081B
D50
4148
56kW
270kW
D4
4148
10kW
4148
IC17 4093B
1kW
D6
100nF
4148
D2
D15
D12
8
S1
S2
COMMON
CATHODE
1kW
D54
4148
10kW
100kW
4148
D9
D7
100nF
10kW
4148
4148
4148
56kW
IC2
NE555
IC3 4017B
100nF
1kW
CON2
1kW
1kW
Health Time LED16
LED17 LLED15
ED15
LED12
TOUCH
LED13
WI N
WIN
1kW
1kW
1mF
LED14
SEQ.
470nF
33nF
LED1
1kW
1kW
LED2
LED3
1kW
1kW
1kW
LED4
LED5
LED6
1kW
LED7
1kW
1kW
LED8
LED9
1kW
LOSE
DS1
7-SEGMENT LED
–
LED10
1kW
S3
5819
D51
Skill Tester 9000, part two
4.7nF
08101241
Fig.5: this overlay diagram shows which components go where. It also shows the correct orientations of all polarised
components like ICs, diodes and electrolytic capacitors. It is divided into 11 sections and can be assembled all in one go if
you are confident and experienced, or in the seven steps outlined in the article text.
Touch, Win and Reset circuits. Fit all
the parts in the Win, Reset and Touch
areas of the PCB, plus LEDs LED11LED14 and the four associated 1kW
series resistors.
Also install IC17 (4093B), the 100nF
capacitor next to it, power switch S1,
1N5819 diode D51, the battery holder
and the 470μF capacitor just below the
holder. When inserting the DIP ICs into
the board, you may have to bend their
leads inward a bit as they will come
splayed outwards.
Practical Electronics | June | 2025
Put a battery in the holder and
check that the 9V rail is OK. If not,
is D51 the right way around? Is S1
switched on?
Now short the terminals of CON3
(eg, using a short length of wire). You
should see the Reset LED (LED11) turn
on. Repeat this for the Win and Touch
inputs at CON4 (with LED13 lighting)
and CON2 (with LED12 lighting).
If that does not work, are IC17 and
the diodes the right way around?
Measure the voltages on the input
connectors; one terminal should be at
0V, while the other should be pulled
up to 9V.
If only one input does not work, look
for solder bridges, especially on the
pins of the 4093 chip, IC17. Check that
its pin 2 goes low when you short the
Reset pads and pin 3 goes high. Verify
that its pin 9 goes low when you short
the Touch pads and that pin 10 goes
high. Also test that its pin 6 goes low
when you short the Win pads and pin
4 goes high.
65
Constructional Project
Photos 1 & 2: the fully
assembled Skill Tester shown
with the game wand (which is
just a looped wire fitted into a pen
case). The design is intended to be
assembled in sections as marked on the
silkscreen. During construction, you can
test each section as its completed.
At this point, you should be able to
trigger Reset and exercise the Touch and
Win inputs and see the corresponding
debug LEDs light.
Health section
2. Now let’s build the Health Clock
and LEDs. Fit all the parts in the PCB
section labelled HEALTH. Do not miss
the 10kW resistor just below IC3.
Get the selection of your coloured
LEDs for LED1-LED10 right! We used
low-cost LEDs with similar brightness.
Make sure the switch you use for S3
is a centre-off type, so you have three
difficulty levels.
Apply power to the board and check
that the 9V rail is OK. You should see
LED17 come on. Short the pads of the
Touch input (CON2), and you should
see LED1-LED10 cycle continuously.
Short the RESET pads (CON1), and
LED17 should relight.
If the above works, great, let’s move
on. If it does not work, check that there
is a clock signal at pin 14 of IC3. If the
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clock signal is missing, check around
IC2. Short the Touch pads and check
that pin 4 of IC2 goes high. If it still
isn’t working, Check that IC3’s CP0
(clock enable) pin (pin 14) is low. If
not, is there a short, or did you forget
to fit the 10kW resistor? Are your LEDs
the right way around?
Check the Out Of Health signal on
pin 12 of IC3 (4017); it should produce
a square wave once per LED cycle.
Check that the debug LEDs for
Touch and Reset still work; if not,
retest the input circuitry. At this
point, LED1-LED10 should be cycling
continuously.
7-segment display should count from
0 to 9 continuously. If there are any
problems, use a similar testing procedure to the section above, but with
IC6 and IC1.
The 555 (IC6) clock output is at pin
3, and the 4026 (IC1) clock input is
at pin 1. The clock inhibit pin on the
4026 (pin 2) should be low, and Reset
pin 15 on the 4026 (IC1) should be
low. Shorting the reset pads (CON3)
should reset the counter to 0. The pin
5 carry output of IC1 should cycle high
and low once per 0-9 count. The Time
counter should be running continuously unless you trigger Reset.
Time section
Siren and Tick section
3. Next comes the Time section and
its 7-segment LED display. Fit all the
parts in that area. Ensure that all parts
in the Time and Health areas are on the
board now. Verify that S2 is a centre-off
type so we get three difficulty levels.
Apply power to the board and
check that the 9V supply is OK. The
4. Fit all the parts in the Siren and
Tick area of the PCB. Watch out, as
the 1μF capacitor may look the same
as the 10μF capacitors. Also solder
IC5, the 4081B in the Game Controller section and the parts immediately
around it: the 100nF capacitor next to
it, two 10kW resistors (one to the right
Practical Electronics | June | 2025
Skill Tester 9000, part two
and one below IC5) and the six diodes
immediately below IC5.
Mount the speaker by gluing it in
place with a few small dabs of super
glue, silicone sealant or Araldite. Keep
it tidy (ie, avoid getting glue where
it shouldn’t go). Wire the speaker to
the pads for CON6; you can omit the
actual screw terminal or mount it on
the underside of the board.
Apply power and check the 9V rail.
You should hear a warbling ‘ping’ from
the speaker; that is the Time Clock tick.
Switch the Time switch between Slug,
Cheetah and Nightmare. You should
hear the ticks change pace from very
slow to very fast.
If there is no sound, probe pins 10
and 11 of IC15 with an oscilloscope
or multimeter reading AC volts. There
should be AC signals on both.
If so, short out diode D43, and you
should get a lot of noise from the speaker. In that case, there is something
wrong with C44, D47, C46 and the
associated parts. Are those capacitors
the right way around?
Now short out the Touch pads
(CON2). You ought to hear a racket
from the speaker (the Touch tone). If
not, check for an AC signal on pins 3
and 4 of IC15.
The signal at pin 3 will have a low
frequency, so you will be able to detect
the individual pulses. Check that the
Touch LED (LED12) lights when you
short the Touch pads. If it still isn’t
working, check for shorts on the board
and parts missing or the wrong way
around.
At this point, the ticking sound
should be running non-stop, and the
Touch tone should be generated if you
short the Touch input pads (CON2).
Win Song section
5. Now fit all the parts in the Win
Song section. There are a lot of different value resistors in the tune section;
double-check the value of each before
you solder it in. Getting resistors off
a double-sided board is possible but
not easy.
If you are not 100% sure, measure
each resistance with your multimeter. Remember to avoid touching the
meter probes when doing this, as that
will affect the measurement of high
resistances.
The 1μF capacitor and 270kW resistor just below IC17 should also be fitted
to the PCB now. They set the period of
the tune sequencers.
Practical Electronics | June | 2025
Apply power to the board and check
the 9V rail. You should hear the ticking
timer noise and the Win Song playing
repeatedly. If there is no sound or only
a single tone, check IC8 and IC9 for
solder bridges. Also check around IC17,
as it generates the clock for the tunes.
Probe pin 14 of IC9 with an oscilloscope (or multimeter on AC volts).
You should find a signal at about 2Hz.
Check pin 3 of IC9 (555 timer). It
should have an audio-frequency AC
signal on it. Are those capacitors and
diodes the right way around?
At this point, you should have the
Win Song running continuously on
top of the ticking sound.
Lose Song section
6. Fit all the parts in the Lose Song
section, then apply power and check
the 9V rail. You should hear the time
‘ping’ with a crazy noise in the background, which is the Win Song and
Lose Song playing on top of each other,
Short pins 1 and 4 of IC9 (555) to
stop the Win Song so you can hear the
Lose Song by itself. Be careful not to
touch any other pins or parts, while
doing this.
If that makes no difference, probe
pin 14 of IC13 with an oscilloscope or
multimeter on AC volts. You should
see a signal at about 2Hz.
Pin 3 of IC14 (555) should have an
audio-frequency AC signal on it. Are
those capacitors and diodes the right
way around?
You can stop the Win and Lose tunes
independently by connecting a wire
to the ground point, then touching
the other end to pin 4 of IC5 or IC14,
resetting that 555 and stopping that
tune generator.
At this point, you should have some
crazy noises happening while power
is applied.
The Game Controller
7. We have built and tested each part
individually, and you should understand how each section operates. Let’s
bring them all together by adding the
control components. Fit all the remaining bits, with the usual cautions on getting ICs in the right way around and
choosing the right one for each spot.
Apply power and check that supply
voltage again. The game will start
straight off the bat. You should hear
ticking, and if you short the Touch
pads (CON2), you should hear the
Touch noise.
You should hear the Lose Song after
the Time counter gets to 9. Try shorting the Reset pads (CON3), which
should restart the game. If you short
the Win pads (CON4) immediately
after starting a game, you should hear
the Win Song.
If that is not happening, verify that
all polarised parts are fitted the right
way around, especially the diodes.
Check for bad solder joints or bridges (shorts) between adjacent pads, or
components that have been mixed up
or misplaced.
The diagnostic LEDs (LED11-LED17)
show the state of every latch and
input. Our earlier tests showed that
the inputs were working, so check
everything around IC4 and IC7, as
the latches are there. Are any pins
shorted?
Mounting the PCB
Our baseboard was about 500mm
long and just deeper than the PCB.
How you go about this part of the construction process should reflect the
space you have and what you want
this game to be.
We marked the holes for drilling
by putting the completed PCB on the
board and drawing through the holes
with a marker, then drilling 4mm holes
at those points. We had shorter screws
on hand, so we countersunk the holes
on the back of the game board to get
a bit of extra length so our screws
reached the standoffs on the top side
of the board.
Once you have successfully mounted the PCB, remove it to work on the
game wire, including the Reset and
Win parts at each end.
We routed the edges of our board
and painted it with clear lacquer to
make it tidy. The charm of this project is its nostalgic design and concept, which relies in no small part on
a tidy appearance.
You need to put some rubber feet on
the board, in the corners of the underside. Otherwise, the screw heads will
scratch everything you put it on, and
it will slip around. Stick-on rubber
feet work well.
The game wire
We used some fencing wire from the
shed for this. It is about 2mm thick
and pretty solid; it can be bent with
pliers or your hands for smoother
curves but is tough enough to take a
hiding. You want to use steel wire as
67
Constructional Project
Photo 3 (left): this photo shows how we secured the game wire to the baseboard. It also shows the wire wrapped around it
to form the Win contact (with heatshrink tubing underneath) and how that copper wire connects back to the terminal on
the PCB. To attach it to the baseboard, the main wire was bent into a loop just larger than the bolt diameter using sharpnosed pliers.
Photo 4 (right): a view of the Reset end of the maze wire, showing how the start contact is bare copper wire from domestic
mains cable, wrapped around the heatshrink insulation and soldered in place. Tinned copper wire would also work here.
This is also the point that the main game wire is electrically connected to the Touch terminal on the PCB.
copper won’t spring back. It doesn’t
need to be fancy or new. If you are
scratching your head, look in your
wardrobe for a metal coathanger. I
reckon that would work just fine.
The shape of the maze is up to you.
The tighter the kickbacks and the more
changes in direction, the harder the
game will be. A loop makes the game
super hard as the wand has to be rolled
to the back of the game to achieve
this; that might be for more advanced
gamers.
Photo 3 shows how we bent the
wire to go through the screws on the
game board.
We drilled holes for 30mm “gutter
bolts” about 30mm apart, allowing
space for a bolt to hold the game wire
and a spot for a second bolt to connect
to the Win and Reset wires at each end
of the maze. We did this to make the
whole thing robust, and so we could
pull the wire maze off and put in an
easier or harder one later.
Our first maze had loops, tight corners, and all sorts of complex curves,
making it nearly impossible to play.
We suggest you instead start simple
and work from there.
Once you have your maze bent up,
but before you bend the loops for the
bolts, insulate about 50mm at each
end with a couple of layers of heatshrink tubing. That will allow us
to wrap 10-20mm of bare copper or
tinned copper wire around the outside to form ‘pads’ that we will connect to the Reset and Win inputs on
the game board.
These inputs have a pullup on the
game board, so if we touch these pads
with a grounded wire, we will trigger
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Reset or Win, respectively. Our wand
will connect to ground, making a neat
arrangement for these inputs to the
game. The required wiring is shown
in Fig.6, although it does not show
the physical layout, just what connects where.
After you have applied the heatshrink tubing, tightly wrap your copper
wire around it. Use pliers to ensure it
is tightly in place, then solder the top
and bottom of the loops together. Don’t
worry; the heatshrink will survive; we
put two layers just to be sure. This is
shown in Photos 3 & 4. We left enough
wire to run to a bolt where we connect
Reset and Win to flying leads from the
game board.
The wand
For the wand, we want something
that is comfortable to hold and to which
we can fix the wire loop that goes
around the maze wire, connected to
our circuit ground.
By connecting the loop on the wand
to ground, we can tap this on the Reset
wire to start the game. If the loop touches the maze wire, it connects to Touch
and, at the end of the game, tapping
on the Win wire wins the game; both
are part of the maze wire.
We used a ballpoint pen case for the
wand (Photo 5). The loop was made
from the same wire, reclaimed from
house mains wiring, that we used to
make the Reset and Win pads.
Fig.6: this diagram shows how the Touch, Reset and Win terminals (CON2CON4) connect to the wand, game wire and start and finish pads. Refer to
the photos to see how we made the required electrical connections, and note
that the ground wire going to the wand can connect to the upper screw of
any of the three terminals.
Practical Electronics | June | 2025
Skill Tester 9000, part two
Photo 5: we made the wand from an
old biro case, some reclaimed wire
(tinned copper wire could be used)
and enough layers of heatshrink
tubing added to make it a snug fit to
the case. Some super glue holds the
whole thing together.
Assembly is a simple matter of
screwing everything together. Make
sure that the wand’s loop is ultimately wired to a ground pin on one of
the Reset, Touch or Win connectors
(CON2, CON3 or CON4). In each case,
the ground side is closer to the top of
the board.
By now, you will realise there is a
bit of work in making this project and
doing so tidily. Still, the basics of a
stable base, something to screw the
wire to and wide enough to hold the
PCB are the essence (see Photo 6 for
our completed version).
Finishing it off
Connect the pad at the start of the
wire to the Reset line (not the ground
side, so the bottom terminal of CON3)
so that tapping the wand here will
start the game.
Connect the main wire to the Touch
connector (bottom of CON2), so touching the wand to the wire will short
the Touch pin and reduce the Health
counter.
Connect the pad at the end of the
wire to the Win connector (bottom of
CON4). This way, everything you need
to run a game is at your fingertips.
Tips on playing
There are three settings each for
speed and difficulty. Noob + Slug makes
the game the easiest, while Veteran +
Nightmare makes it the most difficult
(perhaps impossible)! So start with
Noob + Slug and work your way up
from there. To win, you must move the
want from the start to the end of the
wire with time and health left.
To play a one-on-one game, choose
a difficulty setting and play one game
each. If one player wins and one loses,
the winner is obvious, but if both win,
whoever has the most health left wins.
If both have full health left, the fastest time wins.
To run a tournament, start with the
easiest settings and give each player
one attempt at the game. Anyone who
loses (whether by running out of time
or health) is eliminated.
If more than one person is left, play
again on a higher difficulty setting.
Repeat this until all but one has been
eliminated, or you reach the highest
difficulty setting. In the latter case,
use the rules above to determine the
winner.
When increasing the difficulty, we
suggest going from Noob to Veteran for
Health first, then when you reach Veteran, start speeding up the time from
Slug to Nightmare.
Also, remember that the way you
bend, fold and make loops and kickbacks in that wire plays a big part. Is
your wire tough enough?
Have fun! If you come up with better
tunes than we have, send in your
resistor values so we can try them
PE
ourselves!
Photo 6: the finished and assembled Skill Tester game. It is an updated version of the old wire loop (also called buzz wire)
game. We’ve used an MDF offcut, but you can use whatever timber you have available as long as the size is adequate.
Practical Electronics | June | 2025
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