Touch sensor schematics

Capacitive touch sensors are based on the electrical capacitance of the human body. When, for example, a finger comes close to the sensor, it creates a capacitance to Earth with a value of 30 to 100 pF. This effect can be used for proximity detection and touch-controlled switching. Capacitive switches have clear advantages compared to other types of touch switches (for example 50 Hz or 60 Hz detection or resistance detection), but are often more complex to implement.... [read more]

The purpose of this circuit is to animate shop-windows by means of a capacitive sensor placed behind a post-card-like banner. The card is placed against the glass inside the shop-window, and the visitor can activate the relay placing his hand on the card, from the outside. Especially suited for toy-shops, the circuit can activate model trains, small electric racing cars, lights etc. Further applications are left at user's imagination. Adopt it to increase the impact of your shop-window on next Christmas season!... [read more]

This simple circuit can be used to activate whatever you like, for example, by connecting it to microcontroller, relays, secret alarms, robot applications or just turn on LED1 which lights up as long as you touch the metal plate. The circuit consists of voltage divider R1 and R2, one Schmitt trigger/inverter gate from a 40106 IC, a small capacitor to keep strong RF at bay and LED1 with current limiting resistor R3. The metal plate is connected via a wire to R1. R1 and R2 together form a voltage divider.... [read more]

The modern mechanic switches are improved concerning of old technology. We need however many times to replacement some old switch or to check currents bigger than the durability of certain switches or simple we need something with modern appearance. For he and different reasons is essential the up circuit. It is simple in the manufacture and the materials that use they exist everywhere.... [read more]

The purpose of this circuit is to animate shop-windows by means of a capacitive sensor placed behind a post-card-like banner.... [read more]

The circuits light a 20 watt lamp when the contacts are touched and the skin resistance is about 2 Megs or less. The circuit on the left uses a power MOSFET which turns on when the voltage between the source and gate is around 6 volts. The gate of the MOSFET draws no current so the voltage on the gate will be half the supply voltage or 6 volts when the resistance across the touch contacts is equal to the fixed resistance (2 Megs) between the source and gate.... [read more]