CIRCUITS

This write-up will only cover the absolute basics of most kit components. For more detailed overviews, schematics, and example circuits, see the PDF below:

https://raw.githubusercontent.com/Freenove/Freenove_Ultimate_Starter_Kit/master/Tutorial.pdf

The page numbers mentioned throughout this writeup are referencing this PDF.

(Page 168) Allows independent control of 1 or 4 red 7-segment characters. Each character has a common anode and 8 unique cathodes – 7 segments and a decimal. The 4-character display works a lot like the 1-character display, as it displays only one character at a time and scans through them at a high frequency.  

(Page 126) : 8x8 grid of red LEDs. Requires 16 unique inputs to drive. Functions in a common anode arrangement, in which LEDs in the same row share a common anode and those in the same column share a cathode, making it possible to drive 64 LEDs with 16 pins. Sending power through 2 specific pins will light up a single LED, though the actual wiring is fairly complex.  

(Page 198) Type of sensor that detects vibrations, and closes a circuit once a vibration threshold is reached. 

(Page 188)  16-button keypad. Each button will connect two of the eight output pins. For example, as shown below, pressing ‘B’ will connect X2 and Y4, which can be interpreted by the Pi as a unique input independent from the other 15 buttons.  

Converts USB power or 6.5V – 9V barrel jack power to 3.3V or 5V on a breadboard using jumpers to change output values. Has a switch and an LED to indicate when power is on.  

(Page 98) H-bridge and PWM motor driver that can control the speed and direction of current flow through two < 600 mA devices, often DC motors in RC cars. I did a detailed writeup on the theory and wiring/use of the L293D, which can be found in the box folder.  

Serial in / parallel out shift register - with 3 inputs, can effectively control 8 outputs. Especially useful on devices with few pins, like Arduino microcontrollers.  

Overview: https://www.arduino.cc/en/Tutorial/Foundations/ShiftOut 

(Page 63) Converts analog signals, like those created by potentiometers, to digital signals, in which the analog signal is mapped to an approximate digital value. There are 1024 distinct digital values in the ADC module in the kit, with 0 being off and 1024 being fully on.  

(Page 81) Buzzers are designed to produce sound at different frequencies, depending on their design. Active buzzers are simpler to use, as they only require a power input, but can only output sound at a single frequency. Passive buzzers can be made to produce sounds at a range of frequencies, but require a PWM signal to work. Changing the frequency of the PWM signal will change the frequency of the buzzer’s sound.

(Page 111) A type of resistor that changes its resistance based on temperature. The temperature can be determined using a formula on the referenced page number. Among other things, thermistors are often used in 3D printers to fine-tune hotend temperatures. 

(Page 71)  A type of resistor that changes its resistance based on light intensity. Its resistance will increase as the amount of ambient light it detects increases.  

(Page 104): A highly accurate, closed-loop DC motor with a rotational range of 180 degrees. Servos can be programmed to rotate to any position within their 180 degree range, making them useful for precision applications in robotics, machinery, and others. Lots of gearing provides servos with much more torque than traditional DC motors, and they tend to be more accurate (albeit more expensive) than stepper motors by the nature of being closed-loop. 

(Page 182) Often considered an alternative to servos, stepper motors are types of open-loop motors that move in ‘steps’. Each step is a small fraction of a full rotation, and stepper motors can rotate any number of steps quickly and accurately. Due to the nature of their design, they can also resist rotation when stopped with a great deal of torque. They are often used in applications where low cost and open-loop functionality is important, like in CNC mills and 2D/3D printers. I did a detailed writeup on stepper motors, which can be found in the box folder.  

(Page 115)  Reads input independently on X and Y axes, and can be pushed down to trigger a button. X and Y axis inputs are measured with analog potentiometers, so an ADC module may need to be used in order to interpret the signal the joystick produces digitally. 

(Page 119) MPU 6050 Module: Movement sensor – combines a 3-axis gyroscope, 3-axis accelerometer, and a digital motion processor. Utilizes I2C to communicate.  

(Page 142) 1602 LCD: Small, backlit display capable of displaying 32 total characters across two rows, each having an 8x5 array of pixels to create a character within.

Relays are a type of simple electronic switch that have a huge number of potential use cases. Say, for example, that you want to use a device like a Raspberry Pi to control something that draws a lot of power – big motors, high wattage lights, and USB power cables, for example. These things can’t be wired directly through the Pi like LEDs and small DC motors, as the Pi’s circuitry is too delicate to handle such a large amount of current. It’s in these kinds of situations where relays become useful, as they can read small “trigger” signals from devices like the Pi (and other low current circuits) and use them to turn on higher current circuits.  

Relays are very common in consumer electronics, including automotive electrical systems. Turning on high beams, for example, normally takes a lot of power, but vehicle manufacturers aren’t about to make you pull a big lever to turn them on. Instead, they connect a headlight relay to a simple dashboard switch, making it easy and safe to turn them on and off whenever needed.  

Before using a relay, it’s important to note its rating for current and voltage – exceeding these values can be dangerous. I also strongly recommend against using relays on anything that runs on mains voltage unless you have proper training, as small mistakes or errors can lead to shorts or electrocution. Working with exposed mains wiring should never be taken lightly. Relays can be used with smaller devices, like higher power 12v motors, fans, and other electronics that are much safer to work with and can be used in fun and interesting projects.