Introduction: Coffee Mixer Mod Using Ne555 PWM Speed Regulator
In this project, I will discuss how I improved my coffee/tea mixer by adding a very efficient speed control using a NE555 timer IC. The main motive was to decrease the speed since the mixer initially had no speed control and the speed was a bit too high. Unlike linear regulators, this method produces very little power loss with an increased lifespan. The PWM circuit is pretty simple and small so it can be easily fitted inside the casing.
Supplies
Step 1: Theory
The NE555 creates a PWM signal which basically means, it creates a square wave whose pulse width can be increased or decreased with the help of a potentiometer. The NE555 IC seems to work just fine using the battery of the mixer. Here the BD139 is acting as a switch that turns on and off very quickly based on the signal from the timer IC. The transistor is on when the output is positive and vice versa. Thus by controlling the amount of time the transistor stays on (Ton), we can control the speed of the motor.
Unlike linear regulators, such as LM317T, this circuit produces very little power loss with an increased lifespan. There is very little heat produced with lower power consumption at low speeds.
The only downside to this circuit is that it produces some electrical noise at low speed, but that is not a big problem.
Step 2: Open Mixer and Disconnect Motor
Unscrew and open the mixer. Cut the negative terminal of the motor.
Step 3: Schematic
Build the circuit on a breadboard, connect the battery and motor to the circuit and check whether everything works perfectly. you can change the value of the 1k resistor to other values to get desired range of speeds.
Step 4: Build the Circuit
Build the circuit on a Vero board to make it compact.
Step 5: Drill Hole to Fit the Potentiometer
Use a drill bit or soldering iron to create a hole to fit the variable resistor. Secure the resistor using the nut and attach a knob over the variable resistor.
Step 6: Connect Everything and Complete!
