I'll show you the first logic gate I built. I made it at TechShop.
Microprocessors have millions of gates, but some spare change yields a handful of electronics parts, enough to make a logic gate and to see the beauty of computing one bit at a time.
With two transistors you can create your first logic gate, an AND gate. An AND gate responds when both inputs are high or true. If you’re looking for your black cat, Damian, the thing you want must be both a) black and b) a cat.
Is it black? Is it a cat? Could it be Damian?
No No No
No Yes No
Yes No No
Yes Yes Yes
Now let’s go electric!
Step 1: Parts
Two push button switches (I got mine from a spare parts box at Tech Shop).
Three resistors (two 1 kilo ohm and one 100 ohm)
A battery and connector
4 bits of wire
Step 2: Planning
Step 3: Connecting the Parts
The first transistor’s emitter is connected to the second transistor’s collector.
The last emitter is connected to the LED and last resistor, both of which connect to ground.
Step 4: Testing on a Breadboard
Step 5: Test
Step 6: Make It Permanent
I took a SBU soldering course at Tech Shop (thanks, Bill). Big hint: make sure your metal contacts are solid. Finally, get both metal contacts hot before applying solder to the iron.