Blog
Build logs, project notes, and write-ups from the workshop.
- How to Power a Servo Motor from an External Supply with an Arduino An SG90 micro servo can stall at 650 mA — over 30 times what an Arduino I/O pin can safely provide. Here is why you need an external power supply for any servo, how to wire one, and the one connection that makes it work: common ground.
- How to Use a PIR Sensor to Detect Motion The HC-SR501 PIR sensor is one of the most practical components you can add to an Arduino project. Three wires, a handful of configuration options, and you have reliable motion detection for under $2.
- How to Upgrade RAM in a 2019 iMac 27-Inch — Fast and Easy The 2019 27-inch iMac has four user-accessible RAM slots. Apple charges a fortune for factory upgrades, but a $138 OWC kit takes the machine from 8GB to 32GB in about five minutes.
- LEDs and Resistance — Elegoo Arduino Lesson 3 Why LEDs need resistors, how to read resistor color codes (or just look at the label), how the breadboard connects everything, and what happens when you use a 220Ω, 1kΩ, and 10kΩ resistor side by side. The most fundamental circuit in the kit.
- How to Use an RGB LED with Arduino — Elegoo Kit Lesson 4 An RGB LED is three LEDs in one package sharing a common cathode. PWM on three separate pins controls the color mix. Here is the pin layout, the 220Ω resistors, the PWM-only pin requirement, and the Elegoo sketch that cycles through colors.
- Adafruit GFX Library for Arduino — Draw Graphics on OLED + LCD Displays How the Adafruit GFX library works — coordinate system, screen buffer, and every drawing primitive from drawPixel to drawTriangle, demonstrated on a 128x64 SSD1306 OLED.
- How to Use a DS3231 Real Time Clock with Arduino — I2C RTC + LCD Display Tutorial The DS3231 is the upgrade from the DS1307: a temperature-compensated RTC that drifts only a few seconds per year and needs no external pull-up resistors. Full walkthrough of wiring, library setup, time-setting, and displaying formatted time on an I2C LCD.
- Arduino OLED Display: Connect the 0.96" 128×64 SSD1306 The 0.96" OLED display gives you 128×64 pixels on an I²C bus for about $6. This post covers wiring, library installation, address scanning, and getting the Adafruit example running.
- How to Connect Multiple I2C Devices to One Arduino I2C lets you run up to 127 devices on two wires. Here is how the bus works, why pull-up resistors matter when daisy-chaining, and a working example with a 1602 LCD and an SSD1306 OLED on the same Arduino.
- How to Use an I2C LCD Display with Arduino — Library Install + Code Examples Wire a 16x2 I2C LCD to Arduino in 4 connections, install the LiquidCrystal_I2C library, and use the key display methods with working code examples.