Hi, I made a quiz buzzer system for bar's quiz night.
The system is basically 4 lecterns each with led strips, 100 mm push buttons with a 5v led inside, all connected to a arduino Uno R4 minima.
Buttons and LEDs are on different PINs but associated.
When buttons are active, button LEDs are lit and off when they're inactive.
Whenever someone buzzes, it deactivates all buttons but keeps the LED lit.
The front facing decorative lighting is on a separate 24v circuit and always on when the setup is plugged in.
Now, since the buzzer is behind the lectern and not visible by public or host, i use a nameplate lit by 24v ledstrip as a visual indicator of who buzzed in.
Using the 5 v signal from the arduino to LED, I wired a 2n2222 daisy chained to the LED + to act as a switch for the nameplate.
Nameplate goes dark when buttons are deactivated with only the one buzzed in lit up.
Now, it works but the button LEDs are always off.
If i unplug the nameplate setup, the LEDs lights up.
I expect it to be a voltage drain issue but have no idea how to fix it.
The 2N2222 appears to be backwards, and there is no base resistor to limit current. Also, there is no resistor in series with either LED to limit current there either (it may be that both LEDs have internal current limiting resistors that haven't been mentioned).
Off the top of my head, I'd think something like below would be more like it.
In my experience it's an LED with a built in current limiting resistor and can be hooked up to 5V w/o an external resistor. I've got a handful of them from long ago and have never actually used one in a project.
It's an odd circuit because:
I'm self taught, this is my first project and the first diagram i ever drew. Not only i may have forgotten to draw some components ( the setup is at work drawing from memory) but i may also have skipped crucial components in my design.
Also, this was delivered 2 months ago. Half the parameters changed after it was done.
From 1 board, code is now split into 2 with wireless communication.
This is the last kink to work out before i never touch it again.
Now. That been said.
P2n2222A is wired correctly as it properly acts as a switch.
I ran 2 GND lines in between the different lecterns.
1 line for all the 5v signals and components. It goes back to the board.
1 line for all the 24v- that goes back to the power supply.
The only place where both 5 and 24v are connected is through the p2n2222a transistor (5v to 24v GND).
But you are actually spot on about resistors. I used none.
Yes, i had preinstalled 3v white leds in the buzzers that i swapped for blue 5v with internal limiting resistor.
I'll add 1k resistors following your diagram and that should do the trick.
I'If that doesn'n fix it right away, ll swap back the leds for the original ones if i have to.
Thank you very much for the help.
I really wasn't expecting to have a reply in such a short amount of time.
