Chapter 31 Soldering Circuit Board

Project 31.1 Soldering a Buzzer

We have tried to use a buzzer in a previous chapter, and now we will solder a circuit that when the button is pressed, the buzzer sounds.

This circuit does not need programming and can work when it is powered on. And when the button is not pressed, there is no power consumption.

You can install it on your bike, bedroom door or any other places where it is needed.

Component List

Pin header x2	Resistor 220Ω x1

Active buzzer x1	Push button x1

LED x1	AA Battery Holder x1

Circuit

We will solder the following circuit on the main board.

Schematic diagram

Hardware connection

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Chapter36_03

Chapter36_04

Soldering the Circuit

Insert the components on the main board and solder the circuit on its back.

rendering after soldering:

Front	Back

Testing circuit

Connect the circuit board to power supply (3~5V). You can use ESP32 board or battery box as the power supply.

Press the push button after connecting the power, and then the buzzer will make a sound.

Project 31.2 Soldering a Flowing Water Light

From previous chapter, we have learned to make a flowing water light with LED. Now, we will solder a circuit board, and use the improved code to make a more interesting flowing water light.

Component List

Pin header x5

Chapter36_00

Resistor 220Ω x8

Chapter01_04

LED x1

Chapter01_03

74HC595 x1

Chapter15_00

Circuit

Solder the following circuit on the main board.

Schematic diagram	Hardware connection

Soldering the Circuit

Insert the components on the main board and solder the circuit on its back.

Rendering after soldering:

Front	Back

Connecting the Circuit

Connect the board to ESP32 with jumper wire in the following way.

Code

The following is the program code:

import time
from my74HC595 import Chip74HC595

chip = Chip74HC595(14,12,13)
# ESP32-14: 74HC595-DS(14)
# ESP32-12: 74HC595-STCP(12)
# ESP32-13: 74HC595-SHCP(11)

while True:
    x=0x01
    for count in range(8):
        chip.shiftOut(1,x)  #High bit is sent first
        x=x<<1
        time.sleep_ms(300)
    x=0x01
    for count in range(8):
        chip.shiftOut(0,x)  #Low bit is sent first
        x=x<<1
        time.sleep_ms(300)