Four-bit Adder Demo Board Complete

Four-bit adder demo board, with components assembled

My PCBs arrived from OSHPARK. After assembling on the components, the board worked as expected, and I gave it to my kids to play with.

The two larger DIP switches at the bottom are the 4 bit numbers to be added together. The one small DIP switch is the CARRY IN bit. The four green LEDs at the top represent the output 4 bit number (LSB on the left) and the yellow LED represents the CARRY OUT bit.

If you wish to order the PCB from OSHPARK, here is the url:


This is what it looks like before putting on the components:

Four-bit adder demo board, without components

Here is the schematic:

Four-bit adder demo board schematic

Here is the BOM:

Four-bit adder demo board BOM

The unit needs 5 volt power source, but seems to work fine with six volts, so I found it simplest to hook up a AAA x4 battery pack. You should get a battery pck with an off switch since the 47k pull down resistors will be dissipating a small amount of power even when the LEDs are not lit up.

You may also want to use some epoxy or something to hold the power wires stiff on the board, so they don't get broken off as easily.

This is just an educational project and the project has not been tested or evaluated regarding safety for use with adults or with children.


Alaskalinuxuser, 2021-10-14

Great work! A lot of times things don't work right the first time around, so that's pretty impressive that you got it all right on the first try!

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