Firstly, we need to understand the working principle of the tactile switch. A touch switch usually consists of two contacts. When the switch is pressed, these two contacts will close, allowing current to pass through; When the switch is released, the contact opens and the current stops flowing. This working principle makes tactile switches an ideal choice for control circuits.

Next, we will design a simple circuit that uses a touch switch to control a load, such as an LED light.

1、Circuit component list:

Tact Switch 
Power source (such as battery)
LED lights
Resistance (used for current limiting, LED lights usually require a suitable current to operate)

2、Circuit connection:
Connect the positive pole of the power supply to one pin of the tactile switch.
Connect the other pin of the tactile switch to the positive terminal of the LED.
Connect the negative terminal of the LED to the negative terminal of the power supply.
Set an appropriate current limiting resistor for the LED to prevent it from burning out.

3、working principle:
When the touch switch is not pressed, the switch is in the off state, the circuit is interrupted, and the LED light does not light up.
When the touch switch is pressed, the switch closes, current flows through the circuit, and the LED lights up.
When the touch switch is released, the switch is disconnected, the circuit is interrupted, and the LED light goes out.

4、matters needing attention:
Ensure that the resistance value of the resistor is appropriate to avoid damage to the LED due to overcurrent.
If the power source used in the circuit is AC power, suitable rectification and filtering circuits need to be used.
Expansion:

More touch switches and LEDs can be used to design complex circuits and achieve more functions, such as controlling the brightness or color of multiple lights.