Understanding the Core Components

 An electric Micro Foam Pump replaces the manual mechanical action with two key electronic components:

1. DC Diaphragm Pump: This is the heart of the system. It's a small, self-priming pump that can handle both air and liquid. It creates the pressure and suction needed for the foaming process.
2. Foam Generator Nozzle: This is a special attachment that mixes the liquid and air in a precise ratio and forces them through a fine mesh screen to create a consistent, dense foam.

 By combining these with a simple circuit, we can build an automatic dispensing system.

 Materials and Tools You Will Need

 Electronics:

• 12V DC Diaphragm Pump Module (often sold as "foam pump" or "liquid spray pump")
• Foam Generator Nozzle (usually included with the pump module)
• 12V Small DC Gear Motor (to act as an electric actuator if not using a dedicated foam pump module - see alternative method below)
• Push Button or Motion Sensor
• 9V or 12V Battery and connector
• Transistor (like TIP120) and Diode (1N4001) for motor control
• Breadboard or Perfboard and jumper wires

 Structure & Housing:

• A sturdy plastic container or project box
• Small plastic bottles (for liquid and foam mixture)
• Plastic tubing (that fits the pump nozzles)
• Hot glue gun & strong adhesive
• Wires, screws, and basic tools (screwdriver, wire cutters)

 Method 1: Using a Dedicated DC Diaphragm Foam Pump (Recommended)

 This is the most straightforward and effective method for a true Micro Electric Foam Pump.

 Step 1: Understand the Pump Module

A dedicated foam pump module typically has two inlet tubes (one for air, one for liquid) and one outlet tube that connects to the foam nozzle. When powered, it simultaneously draws liquid and air, mixes them internally, and expels them as foam.

 Step 2: Assemble the Liquid System

1. Prepare your soap mixture (typically 1 part soap to 3-4 parts water). Do not use thick or creamy lotions as they can clog the pump.
2. Connect one piece of tubing to the liquid inlet of the pump and place the other end into your soap mixture bottle.
3. Connect another piece of tubing to the air inlet, leaving it open to draw in air.
4. Attach the foam generator nozzle to the pump's outlet.

 Step 3: Build the Control Circuit

Create a simple circuit:

1. Connect the positive terminal of your battery to one terminal of the push button.
2. Connect the other terminal of the push button to the positive wire (red) of the pump.
3. Connect the negative wire (black) of the pump directly to the negative terminal of the battery.
4. Optional: For a touchless system, replace the push button with an Arduino and an ultrasonic sensor (like HC-SR04) to trigger the pump when motion is detected.

 Step 4: Housing and Final Assembly

Place all components inside your project box. Secure the pump and battery firmly. Mount the foam nozzle so it protrudes slightly from the box, and position the push button or motion sensor conveniently. Ensure all tubing is neatly routed and secure.

 Method 2: The DIY Gear Motor Actuator (Alternative Approach) 

If you cannot find a dedicated foam pump, you can automate a manual Foam Dispenser Pump.

 Step 1: Modify a Manual Pump

Take apart a standard manual Compact Foam Pump. You need to attach a small cam or lever to the pump's piston. This cam will be connected to the shaft of the 12V DC gear motor.

 Step 2: Build the Driving Circuit

This circuit is slightly more complex as the motor needs a pulse of power, not continuous power.

1. Use a transistor (TIP120) as a switch to control the motor, as the motor draws more current than a microcontroller can handle.
2. Connect a microcontroller (like an Arduino) or a 555 timer circuit to send a short pulse to the transistor when the button is pressed.
3. Wire a flyback diode (1N4001) across the motor terminals to protect your circuit from voltage spikes.

 When activated, the motor spins the cam, which pushes the pump's piston down, dispensing one portion of foam.