# Quiz buzzer system

#### Belle

Apr 14, 2017
13
I am a teacher and science bowl coach for an elementary school. It was my first year as coach and found out the students really need to practice the mechanics of the game. We need an 8 playerlock-out buzzer system. The systems we could buy are too expensive and I do love making things. Unfortunately I do not have the electrical knowledge to build a system but would love to learn how. I need help!

I have been looking online for systems and found this one http://basbrun.com/2012/05/30/quiz-buzzer-system/. This next system looks like the one the students use and I would like to get as close to that as possible. http://www.buzzersystems.com/trad/index.htm

I have looked over schematics but don't understand them well enough to put something together. Is there any way someone could help me get a parts list and instructions to put it together?

#### 73's de Edd

Aug 21, 2015
3,463
Mon petite . . .Belle . . . .

Ohhhhhhh . . . the ADDED cost ( or profit gouging ? ) of making dedicated products for minimal marketing.

That’s being just as easy accomplished, as building the simple circuitry I place for you below, more like $5 of parts instead of$200.

You just double the circuitry for 8 players or break up as being two 4 participant play offs.

The player who hits his button FIRST lights his light (sounds an added buzzer) and locks out any other players later hits.

CIRCUIT:

FULL INFO:

http://www.electronics-project-design.com/EducationalGame.html

Info assist available . . . .from members here.

PLUS / OR you probably have some former students who have, by now, developed fully into their Eeeee-lectronic Nerds state, who could easily build this up for you on the smallest plug in breadboard.

73’s de Edd

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#### Belle

Apr 14, 2017
13
I was thinking of going to our community college to look for "electronic nerd students" and I do say that with affection. I am a tree hugger at heart. It would be easier, but that would take the fun/ frustration out of doing it myself.

What is the power source for your design?

#### 73's de Edd

Aug 21, 2015
3,463
Four 1.5 Alkaline cells . . . . . for a year + run time its kid pruff . .and SHOCK pruff..

#### 73's de Edd

Aug 21, 2015
3,463
For your further consideration . . . . .

After a synapse firing within my rat trap memory cache. All was remembered !

Decades ago, the right revered and esteemed Charles Wenzel revealed this simple circuitry for also accomplishing, that electro-feat which you so desire.

Its main appeal is its utter degree of simplicity in construction by the use of few discrete parts and minimal interconnecting wiring.

It falls within the post Neanderthal-Pre Cro-Magnon expertise in its sticks and stones technology.

It’s being just about as simple as it gets.

Here is all that is being involved:
• 12 volts of battery power sourcing
• 5 flashlight bulbs
• 4 SCR’s or Triacs
• 1 spst power switch / for the teechur reset switch
• 1 9V Zener diode
• 1 100 ohm resistor
• 4 remoted pushbutton player switches, each using 6 foot interconnecting paired speaker cable.
WHY? . . . .To be able to restrain the cable pulls-yanks-jerks of either elated winning or dismally defeated players, and not having a dumping of the whole contraption off the table and onto the floor.

House the individual pushbutton switches inside of spent lipstick cases to add that just right dash of estrogen flair into the build / mix.

The use of the SCR /or/ Triacs require a bit of an increase of voltage to work reliably, thus the uppage of supply voltage to 12 VDC . . . but still being attainable thru (8) series arranged 1.5 volt cells in a holder.

Also they need a bit more current passing through them, thus the use of flashlight bulbs; however an additional LED with a drop resistor could be placed across a bulb.

RELEVANT SCHEMATIC + INTERCONNECT WIRING

This is the whole article, plus the possible add on of a buzzer.

#### AnalogKid

Jun 10, 2015
2,688
The first schematic will work, but expanding it to 8 inputs gets a bit messy growing an 8-input OR gate. I've done this without doing that by using a 74AC573 octal transparent latch with a resistor network and one transistor forming a NOR gate. I can post that if anyone is interested.

The basrun link is bizarrely complex and requires a programming system.

BuzzerSystems will work well with the absolute minimum effort, but time is money. No, it is not overpriced, but it should be a bit more professionally packaged.

The second schematic is one of the great logic designs of all time, and can be adapted to LEDs.

You can find many more schematics and products by searching for 'game show circuit'.

EDIT: OR - the 573 can do all of the work with zero external gating. Hmmm...

ak

#### AnalogKid

Jun 10, 2015
2,688
First pass at a reduced component count game show circuit. This is an extension of the circuit in post #2. By changing the logic polarity of the inputs and outputs, the LEDs act as an OR-ing diode array into R1, with the correct logic polarity to drive the latch input. SW9 is the moderator's reset control. It works only if all input switches are open.

Only positions 1 and 8 are detailed; 2-7 are identical.

In circuits such as this I like resistor networks because of the way the layout works out, but RN1 can be replaced by 8 individual resistors.

The AC series of CMOS parts can source or sink 20 mA, more than enough for an LED. Adjust R1 for brightness. At 9 V, the minimum value is 360 ohms.

OOPS - got the latch logic polarity backwards. New schematic to follow.

ak

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#### hevans1944

##### Hop - AC8NS
Jun 21, 2012
4,780
I am confused. If the LE input is initially held low by R1, and none of the outputs is yet high, and all the inputs are pulled low by RN1, and none of the switches SW1 through SW8 are closed, how does closing any of SW1 through SW8 propagate a logic one output to LEDs D1 through D8 and hence from one of their cathodes (wired OR connection) to the LE input, which must be high for D-input data to propagate to the outputs and to the LEDs?

#### AnalogKid

Jun 10, 2015
2,688
It is the same logic as in post #2. U1 is a transparent latch. When LE is low, it sits there as, effectively, eight non-inverting buffers. When any input goes high, it goes through to its LED and R1. This pulls LE high, clocking all latches and freezing the system.

OOPS - got the LE polarity backwards. I deleted my schematic, and will fix it.

ak

#### Arouse1973

Dec 18, 2013
5,178
I have done this with CD4069 configured as a latch and the output of the latch disables the other buttons from being pressed. You can add as many as you need.
Thanks

#### hevans1944

##### Hop - AC8NS
Jun 21, 2012
4,780
It is the same logic as in post #2.
Not really. In the schematic shown in post #2, the two NAND gates form an RS latch as long as the dual 2-bit latches are in transparent, pass-through, mode... which they will be as long as the active-low Latch Enable inputs (pins 4 and 13) are high, i.e., NAND gate 2Y output is high.

Pressing the RESET button guarantees that NAND gate 2Y output will go high, enabling transparency. So, if none of the contestant switches is pressed, all the latch outputs will be high because the latch inputs are pulled high by pull-up resistors R1 through R4 connected between Vcc (+5 V) and the normally-open contestant switches S1 through S4, whose other pole is connected to common. However, momentarily closing any of the contestant switches causes one of the four outputs to go low, which causes NAND gate 1Y output to go high, which causes NAND gate 2Y output to go low. This latter action cancels the latch transparency causing the latches to remain in their current state.

Note there is the possibility of a "race" condition if two (or more) contestant switches are pressed "simultaneously," which is defined to mean in a short enough interval to propagate the switch positions through the latch before the transparency condition is disabled by propagation delays through the two NAND gates. If this occurs, more than one output will be latched low. This not really a consideration with humans pressing switches, but there is a definite possibility that it can occur. It is accommodated in high-speed logic by the implementation of a priority tree that favors (priortizes) the occurrence of "simultaneous" conditions.

#### AnalogKid

Jun 10, 2015
2,688
Not really. In the schematic shown in post #2, the two NAND gates form an RS latch as long as the dual 2-bit latches are in transparent, pass-through, mode... which they will be as long as the active-low Latch Enable inputs (pins 4 and 13) are high, i.e., NAND gate 2Y output is high.
U2A is an inverting-input OR gate (if any input goes low, the output goes high) which is turned into a NOR by U2B. An OR function of some kind is a central element of all game show circuits. It doesn't form a latch with the 7475 in the normal sense, but it does drive essentially drive a transmission gate that controls its own input. I think we agree on how the circuit works, whatever the semantics.

ak

#### AnalogKid

Jun 10, 2015
2,688
OK, second pass at a minimal game show circuit. Same basic logic description as post #7. Note that the OR-ing diodes are LEDs, with a Vf of around 2 V. To meet CMOS AC logic levels, best to run the circuit on 9 V or more. It should work on 6 V, but this is untested.

ak

#### Attachments

• GameShow-1-c.pdf
10.3 KB · Views: 74

#### KMoffett

Jan 21, 2009
723
For your further consideration . . . . .

RELEVANT SCHEMATIC + INTERCONNECT WIRING

View attachment 33300

This is the whole article, plus the possible add on of a buzzer.

Used that circuit many years ago. Simple, expansable,worked great. I added a buzzer across the moderator's lamp.

Ken

#### AnalogKid

Jun 10, 2015
2,688
The ultra-ultra-simplest circuit uses neon bulbs as both the latch element and indicator. I've lost it somewhere.

ak

#### 73's de Edd

Aug 21, 2015
3,463
Sir AK

Indeed the Neons are . . . . BUT ! . . . . . how could you lose it, it’s so easy to recreate in your minds eye.

Plus I wanted no possibility of shockee-shockee hazard with kiddos.

Le circuit . . . .

The unit is initially set up in BRIGHT light with the applied B+ and brought on up until one of the neon fires on its own .Then that voltage is decreased about 25% to then be the supply voltage which probably will be in the 100VDC range with the values shown.

THEN . . . . . . Whoever pushes his button first to get the additional voltage to fire his neon has all of the others locked out, by virtue of his unit stealing all of the power.

If interfacing to solid state circuitry was additionally needed, optical isolators could be made with each individual neon lamp.

73's de Edd

#### Belle

Apr 14, 2017
13
wow, I have a lot of learning to do to understand what you nice people are talking about. I have been watching videos on reading schematics and how to transfer all that to a breadboard. I would like to have the buttons and lights in project boxes and enough wire (7 feet or so) from the reset switch. The students can sit on either side of the teacher (4 one side and 4 on the other) controlling the game and asking the questions or be able to have 4 and 4 facing each other. For the science bowl team, they will be looking at a monitor in front of them with the question and images played like jeopardy.

At our science bowl competition, the student buttons and LED are in a small box about 2x4x1.5 (close to that) then long cables run to a large reset box with light, buzzer (it buzzes once or twice for the teams) and a reset toggle switch. I would like to system to resemble that so they get comfortable with how it all works.

How would the student buttons (momentary push buttons?) be connected to the main reset box, which I guess would contain the breadboard.

Again I am very grateful for all your help.

#### 73's de Edd

Aug 21, 2015
3,463
Mme . . .Belle . . . . . .

Have you done all of your studying and decided if this is a task for you to build or might you want a techno assist from the aforementioned people?
Any ideas for all of the 8 player housings and main unit for the cases ?
Cat-5 cable should meet or exceed the power and adjunct physical abuse requirements for the 8 interconnect cables.
I never have checked to see if dirt cheep lengths have shown up in the Dollar stores yet.
Some cheap housings might be found there . . .in disguise . . .also and dolled up / professionalized with a coat of black spray paint.
Whatever you use, to give some heft and "quality" I would also suggest an internal ballast baggie filled with pebbles or cast aside lead wheel weights used in their balancing, like you / I would find at the tire store bay in a
5 gallon bucket at Wally Woild,
(If fully engaging your female prowess, mystique and wiles . . . . surely he will even carry them to your car. )

You say . . .
(it buzzes once or twice for the teams)

Is that being
Once for one team, to aurally be identified and twice for the OTHER team ?

You say . . .
How would the student buttons (momentary push buttons?) be connected to the main reset box, which I guess would contain the breadboard.

I would use the above mentioned CAT-5 computer wiring cable or some older cast off phone wiring cable .

The official one does not have a light at each remote . . .only at the main unit . . .right ?

73's de Edd

.

#### AnalogKid

Jun 10, 2015
2,688
A better and more reliable arrangement is to have only the buttons at the contestants locations, and put all of the lights, electronics, and buzzer in the control box at the moderator's desk. In this way the contestant boxes have nothing but a switch, and only two wires going to each. Two-wire lamp cord is low cost and very reliable. Arrange the LEDs in the control box to match the locations of the contestants.

Think about what contestants hold in Jeopardy. You can make one easily. A small pill bottle with the pushbutton switch mounted in the lid and the wire coming out of a hole in the bottom of the bottle is easy to make and repair. Hold it in the hand and press the button with the thumb. It is called a pickle. Grayhill makes one if you have money.

Use a tape measure to determine how far apart two contestants have to be for comfortable seating, then sketch the floor plan on a blackboard and determine the wire lengths. HINT: it is much more than 7 feet.

ak

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#### Belle

Apr 14, 2017
13
Bonjour

I have studied and found more questions than answers. I emailed our local community college electronic department and while the person was very nice and offered their students could make it project next spring, that does not help me now. She also said it may end up costing me a couple hundred dollars to make on my own. So...I would still like to make one and see how low cost I could make it and still have it look like a "professional" set up. Although, I am the recycling coordinator and re-using parts or finding creative ways to make what I need is not a issue for me.

The contestant boxes do have a light and button but would not have to be a light on the contestant push-button box. The lights could be on the main control box. The only reason I prefer a box with the button instead of the pickle is because that is how the system is set up for the actually competition. But the pickle is a possibility if the other does not work out. A box would need something to weight it down so it would not slide around. The boxes that would house the push button could be any kind of plastic box? One that I could cut a hole into for the button and wire.

If I put just a button on the box, it would need only two connection wires. As for length, contestants sit no more than 2 feet apart so I guess the farthest most person would need like 10' - 12' of cable.
I would need 100' of cable to get eight 12' lengths plus a little extra to make connections.

The buzzer in the system beeps once for one team and twice for another. It allows for quick recognition to which team is answering and keeps students alert.

And as for the comment "(If fully engaging your female prowess, mystique and wiles . . . . surely he will even carry them to your car.)" that is a bit insulting. While manipulating people to get what you want is done by a lot of people, it is not very kind. Simply asking for assistance would be better. ;-)

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