Make It With Matty

The Summing Amplifier In this part of the op-amp series, we’re going to build and test summing amplifiers . A summing amplifier combines multiple input signals into one output , making it one of the most useful and flexible op-amp building blocks. In this post we will: Build two types of summing amplifier Measure real voltages on the bench Match the math directly to what we measure Highlight practical limitations with single-supply op-amps What Is a Summing Amplifier? A summing amplifier is an op-amp circuit that adds multiple input signals together and produces a single output voltage. Key idea (very important): 👉 Summing amplifiers add currents , not voltages. 👉 The op-amp output converts the summed current back into a voltage. Each input voltage is converted into a current by a resistor. Those currents are summed at the op-amp input and converted back into a voltage at the output. There are two basic types of summing amplifiers: - Inverting Non-Inverting Type 1 — Inverti...

Building XOR Gates with the 74LS86 The XOR (exclusive OR) gate is one of the most interesting logic gates, it outputs HIGH only when its inputs are different . In this post, we’ll build and test it using the 74LS86 TTL chip. What You’ll Need 1 × 74LS86 IC (Quad 2-input XOR gates) Breadboard + jumper wires 2 × push buttons (for inputs) 2 × 10 kΩ resistors (pull-downs) 1 × LED (any colour) 1 × 330 Ω resistor (for the LED) 5 V power supply (or Arduino 5 V pin) How the XOR Gate Works An XOR gate compares two logic inputs (A and B). It outputs HIGH when only one input is HIGH, not both. Think of it like “either/or but not both.” Pinout (74LS86) The 74LS86 contains four independent XOR gates. Typical pin connections: Each set of three pins (A, B, F) is one AND gate. Circuit Diagram Wiring the circuit Connect pin 14 to +5 V and pin 7 to GND . Use pins 1 and 2 as your input A and B by connecting +5V to one side of the push button and the other side...

Building a NAND Gate (74LS00) If you’ve been following along with the other gate projects (like the NOT, AND, or OR gates), the NAND gate is your next essential stop. It’s one of the most important logic gates, in fact, every other gate can be built using NANDs alone! In this post, we’ll wire up a 74LS00 TTL IC , test it using an LED, and see how it behaves in action. What You’ll Need 1 × 74LS00 IC (Quad 2-input NAND gates) Breadboard + jumper wires 2 × push buttons (or jumper wires for manual input) 2 × 10 kΩ resistors (pull-down resistors) 1 × 330 Ω resistor (for LED current limiting) 1 × LED (any colour) 5 V power supply (or Arduino 5 V pin) How the NAND Gate Works A NAND gate is the opposite of an AND gate: It gives a LOW output only when both inputs are HIGH . Truth table: So, the NAND is just “NOT (AND)”. Inside the 74LS00 , there are four separate NAND gates you can use, great for experimenting or combining into bigger logic circuits. Pinout (74...

Building a NOR Gate (74LS02) If you’ve been following the digital logic series, you’ve seen the NOT, AND, and OR gates in action. Now let’s explore the NOR gate,  a gate that only goes HIGH when none of its inputs are HIGH. In this post, we’ll build and test one using the 74LS02 TTL IC . What You’ll Need 1 × 74LS02 IC (Quad 2-input NOR gates) Breadboard + jumper wires 2 × push buttons (or jumper wires for manual input) 2 × 10 kΩ resistors (pull-down resistors) 1 × 330 Ω resistor (for LED) 1 × LED (any colour) 5 V power supply (or Arduino 5 V pin) How the NOR Gate Works A NOR gate combines the logic of OR and NOT: it outputs HIGH only when all inputs are LOW. Think of it as: “If neither A nor B is pressed, the output is ON. If either (or both) are pressed, the output turns OFF.” Inside the 74LS02 The 74LS02 contains four independent 2-input NOR gates. Each one can be used separately, perfect for experimenting or chaining logic. Pinout (74LS02...