Last weeks useful schematics

Last Updated or created 2023-03-25

While working on my game, i had to come up with some solutions i could not find an answer for on the internet.

I’m not going to post every little detail of my game on this blog, my main reason is sharing my experiences and solutions.


16 Switches on a Wemos Arduino. While push buttons are easier to connect, I needed ON/OFF switches.
Push buttons are easy, there is only one active, so 4 enable lines and 4 scan lines and you’re golden.
16 Switches can be enabled all at the same time.
So you need some extra components to get a good result (0-65535)

Above schematic works, you need 4x 1k Pull-up resistors and 16 diodes. I used 1N4007

CONTROLLING 24V using Arduino and a buck convertor

Next problem, i’m using some elevator buttons for a project. These have build-in leds but run at 24V.
I only have 5V from the Arduino.
Regular leds you can connect directly to the Arduino using a 220ohm resistor.
So i used a Buck-Step-Up-Convertor. This little module converts 5V to 24V. (You can control the output voltage using a variable resistor)
To control the lamp/leds i used a PN2222a transistor to switch the lights on/off using a pin of the Arduino.

MT3608 Convertor
  • Input voltage: 2V-24V DC
  • Output voltage: 5V-28V DC
  • Output current: 2A (max), 1A (recommended), <100mA (input <4.0V), <50mA (input <3.5V)

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