by SV3ORA
The LED Zapper game final version
The LED Zapper game, is a total revision from the LED zeppelin game. It uses the storage charge in a capacitor as a game core function. The purpose of the game is simple: Light up all the LEDs in sequence by pressing the button, but only at suitable time intervals (when pilot LED is on).
If the button is pressed in all other time intervals, the LEDs will start to switch off in sequence. As more LEDs are lighted up, the game becomes more difficult and more button presses are needed to light up the next LED. If the button is not pressed for some time, the LEDs automatically start to switch off in sequence, so you have to be quick. The switch-off rate, depends on the current LED that is switched on in the sequence.
The game provides a way to select the hardness (level), by means of the 100K potentiometer in the multi-vibrator stage. This basically shortens the period that the button is allowed to be pressed, in order to light up the next LED in the sequence. Additionally, the more hard the level, the quicker the LEDs are switched off when the button is not pressed for some time and also the quicker the LEDs are switched off when an inappropriate button-press is done.
Game sound is provided by means of a negistor oscillator, driving a piezoelectric speaker and related circuicity. The audio oscillator beeps when the pilot LED is on. As more LEDs are switched on, the oscillator starts to beep when the pilot LED is off as well, but at a different frequency from the one when it is on (dual beep). This frequency is raised as more LEDs in the sequence are switched on, providing a way to play the game even without watching the LEDs.
The LED Zapper game current schematic
Original game and some initial modifications are shown below
This is my modification to the LED Zeppelin analogue game which is IC free. It uses only transistors and as an advantage you get the ability to set the difficulty of the game to the desired level. It also consumes less power. I used multiple color LEDs for my version.
Before I describe my
modification, I provide the information to build the original one, which uses an
IC. So here it is:
LED Zeppelin is a game of patience. It's like getting a kite into the air.
It goes up slowly but the slightest mistake will bring it down like a lead
balloon.
The name of the game, LED Zeppelin, is a play on words. It comes not from
the pop group of the same name but from Graf Von Zeppelin, a German who invented the first rigid air ship in 1900.
The association fits perfectly. The game consists of six LEDs and an
indicator LED that flashes at a rate of about 2 cycles per second. A push
button is the "Operations Control" and by carefully pushing the button in
synchronisation with the flashing LED, the row of LEDs will gradually light
up.
But the slightest mistake will immediately extinguish one, two or three LEDs.
The aim of the game is to illuminate the 6 LEDs with the least number of
pushes.
HOW THE (original) CIRCUIT WORKS
The circuit consists of a three-inverter CMOS clock-oscillator driving Q8 that
flashes the LEDs on and off. The other output from the oscillator is used to
charge up the 470u electrolytic C2, via R3.
The output from pin 3 is in the form of a square wave only slightly less than
the supply voltage and is about 7.5v to 8v in amplitude. The frequency at which
the circuit works is governed by R1, R2 and C1 and is approximately 2Hz.
Charging of the 470u electrolytic is exponential so that initially the voltage
increments on the capacitor will be high when it is beginning to charge. Each
time the button is pressed a small amount of energy is fed into C2. This voltage
appears at the base of Q1. Q1 is connected as an emitter-follower and the same
value of voltage will appear at the emitter, less 0.6v base-emitter voltage
drop.
This voltage is then fed to the base of six transistors Q2 to Q7 that drive LEDs
1-6 via current limiting resistors. Each of these transistors will turn on
according to the voltage on the 470u electrolytic.
When the voltage rises to 0.6v, Q1 will turn on. For Q2 to turn on its base must
be .6v higher than the emitter. Q2 has a forward-biased diode in its emitter and
the voltage drop across it will be .6v. The base of Q2 must be .6v above the
emitter, making it .6v plus .6v or 1.2v This means the voltage on C2 will be .6v
plus .6v plus .6v or 1.8v for the first LED to be fully lit.
The emitter of Q3 is connected to the base of Q2 so that a further .6v will
turn it on. At each successive .6v rise the next transistor in the chain will
turn on until finally Q7 will turn on. This transistor drives the top LED that
is the highlight of the game. When you have LED 6 pulsing you really feel a
sense of achievement.
Should the button be pressed when the oscillator is low, diode D1 is forward
biased and the charge on C2 will rapidly discharge through R4. Since the voltage
increments become smaller as the 470u becomes fully charged, to light the top
LED requires significantly more pushes than LEDs 1 and 2.
If, however, the button is pushed too long, the discharge will be greatest when
the capacitor is nearing full charge and an error here will lose the gain made
by many pushes. This is where the skill of the game comes in. The charging of
the capacitor is "out of phase" with the flashing of the LEDs. This means the
button must be pressed when the LEDs are extinguished. To turn the game off or
restart it, push the button when the LEDs are lit. This will remove the charge
on C2 and eventually every LED will go out.
|
PARTS LIST for the original version |
|
1 - 270R 1 - 330R 1 - 390R 3 - 470R 3 - 1k 2 - 2k2 1 - 3k3 1 - 4k7 1 - 10k 1 - 22k 1 - 56k 1 - 470k 1 - 4u7 16v PC mount electrolytic 1 - 470u 16v PC mount electrolytic 7 - BC 547, or 2N 2222 transistors 1 - BC 557 or 2N 3906 or 2N 2907 transistor 1 - CD4011 IC 1 - 3mm (1/8") red LED 6 - 5mm (1/4") red LEDs 2 - 1N 4148 signal diodes 1 - 14 pin IC socket 1 - push button 1 - battery snap |
HOW TO PLAY
The 3mm (1/8") LED begins to flash when the battery is connected. This
indicates the flash rate. To start the staircase of LEDS flashing, push the
switch a number of times, (when the LED is extinguished). After a few pushes you
will see the first LED flash faintly. Keep in step with the off periods and you
will gradually increase the illumination. The rest is up to you.
The LED ZEPPELIN game can be played a number of ways. The most popular way
is to count the number of pushes required to get the top LED flashing with
reasonable brightness. The player with the least number of pushes wins.
Another variation is to cover the six LEDs with black tape leaving just the
indicator LED flashing. The object of the game is to see how many LEDS can be
set flashing with a certain number of pushes. Start with 50 pushes per player.
Push the button 50 times then remove the tape and read your score. You can make
certain adjustments such as 3.5 or just over two LEDs flashing.
When used competitively like this, the game provides a means of assessing
your reflex time and co-ordination.
Now let's modify the game to use only transistors
What we basically need to modify is the clock oscillator. I replaced the oscillator with a variable mark/space ratio multivibrator.
The circuit includes both sure-start and waveform-correction diodes. I used 2N2222 for all the NPN transistors in the game and 2N2907 for the PNP ones. I also had to change R2=R3=3.9K and C1=C2=4.7uF on the above multivibrator schematic, to work on a lower frequency required. The negative poles of these electrolytic capacitors are connected to the bases of the transistors. R5 potentiometer is used to vary the mark/space ratio and thus provide a means of setting the game hardness. One output of the multivibrator circuit above is connected just before the push button (pin 3 of CD4011 in the original schematic) and the other is connected just before the base resistor of Q8 (pin 10 of CD4011 in the original schematic) If the circuit cannot light up the LEDs when pushing down the button, swap the outputs connections to ensure correct operation.
