Build a quiz board that indicates right answers AND wrong ones

crutschow

Joined Mar 14, 2008
38,913
Also, is this how i would wire everything up(See Diagram Below)? dont mind my MS paint it was the quickest thing i could use.
Yes, that's how you would wire it, except you need 5 wires and 5 diodes for 5 questions.
Here is my shopping list.
Looks okay but you are ordering from several different places, which adds shipping costs. See if you can order everything from one place, like Mouser or Sparkfun.

You are ordering 300 diodes when you only need 5 (order 10 or so).

The LEDs need a resistor in series with them to limit the current or they will blow, so you need to buy a few 200Ω resistors, 1/4 or 1/2 watt.
 

Jacob_1080

Joined Jul 15, 2017
24
Yes, that's how you would wire it, except you need 5 wires and 5 diodes for 5 questions.
Looks okay but you are ordering from several different places, which adds shipping costs. See if you can order everything from one place, like Mouser or Sparkfun.

You are ordering 300 diodes when you only need 5 (order 10 or so).

The LEDs need a resistor in series with them to limit the current or they will blow, so you need to buy a few 200Ω resistors, 1/4 or 1/2 watt.
Ya i know im ordering from alot of different places but i got everything that i could from amazon with prime where it will be here in 2 days with free shipping. Ill narrow the list down later this was just a rough list to give to the owner for the time being.
Haha I didn't notice that there were 300 there...
So does nothing need to wire up to the normally open on the relay? Its just kinda confusing me as to how this works but i guess i dont have to under stand it i just need everything to work so if you say it works ill trust you. Thanks so much for the help and if i have any more questions ill defiantly be back.
 

GopherT

Joined Nov 23, 2012
8,009
The owner of the museum wants one green and one red light.
I've got my shopping list made up but i need to know what type of resistor I need. im going to use these https://goo.gl/1hvW69
Also, is this how i would wire everything up(See Diagram Below)? dont mind my MS paint it was the quickest thing i could use.
Here is my shopping list.
Quiz Board
AA Holder $7.49- https://www.amazon.com/LAMPVPATH-Ba...0145&sr=8-3&keywords=4+aa+battery+holder+snap
Diodes $5.94- https://www.amazon.com/McIgIcM-1n41...&qid=1500770467&sr=1-1&keywords=1N4148+diodes
LEDs $5.59- https://www.amazon.com/McIgIcM-Asso...1500770566&sr=1-1&keywords=red+and+green+leds
Wire $6- https://www.sparkfun.com/search/results?term=22awg stranded coneccti
Relay x3 $4.05- http://www.mouser.com/ProductDetail...E-14-DC6/?qs=sGAEpiMZZMs8I5ltipPMAB4M4dFz0oFi
Order this stuff from Taydaelectronics.com
One order, $8 for parts or less plus about $3 to $5 for shipping.

IMG_0041.PNG
 

crutschow

Joined Mar 14, 2008
38,913
Its just kinda confusing me as to how this works
It's quite simple.
If the Ans and Select probes go to the same horizontal wire (correct answer) the Green LED is illuminated and the relay is energized from the battery.
This opens the normally-closed contact on the relay, preventing the Red LED from also illuminating.
This current flow is shown by the red lines on the left schematic.

If the Select probe (green wire) is connected to a different wire then Ans (incorrect answer), than the relay and Green LED are not energized, and the Red LED is illuminated through the diode of the wire the Ans probe is connected to.
This current flow is shown by the red lines on the right schematic.

upload_2017-7-22_23-35-45.png
 

Jacob_1080

Joined Jul 15, 2017
24
Alright that makes alot more sense now. i just want able to wrap my head around it . Whats with the earth ground at the bottom? Also i was having trouble finding those resistors. i was able to find some 330Ω 1/6th watt resistors and some 1kΩ 1/4th watt resistors.
 

crutschow

Joined Mar 14, 2008
38,913
I was looking on spark fun because i was already planning on ordering stuff from there.
Yes, they have a meager assortment of resistors.

You could buy this resistor pack.
If that's more than you want to spend, use the 330Ω values.
The LEDs will likely still be bright enough for your purposes.
You could also use five 1kΩ in parallel to get 200Ω.
 

Jacob_1080

Joined Jul 15, 2017
24
Yes, they have a meager assortment of resistors.

You could buy this resistor pack.
If that's more than you want to spend, use the 330Ω values.
The LEDs will likely still be bright enough for your purposes.
You could also use five 1kΩ in parallel to get 200Ω.
So either use 1 330Ω 1/6th watt resistor or 5 1kΩ 1/4 th watt in parallel? Which would be better?
 
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