Various diagram: Touch

Showing posts with label Touch. Show all posts

Wednesday, October 22, 2014

12V Touch Switch Exciter

This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits. It can support a cable length of about 2500 feet. A typical remote switch circuit is also shown as well as a receiver circuit for those switches.

Source: DiscoverCircuits

Monday, October 20, 2014

TOUCH SWITCHS

TOUCH SWITCH 1

This circuit detects the skin resistance of a finger to deliver a awfully tiny current to the super-alpha try of transistors to show the circuit ON. The output of the "super transistor" activates the BC 557 transistor. The voltage on the highest of the world is passed to the front of the circuit via the 4M7 to require the place of your finger and also the circuit remains ON.

To turn the circuit OFF, a finger on the OFF pads can activate the primary transistor and this may rob the
"super transistor" of voltage and also the circuit can close up.

TOUCH SWITCH-2

This circuit detects the skin resistance of a finger to show the circuit ON for concerning one second. The output are often taken to a counting circuit. The circuit consumes no current when in quiescent mode:

Thursday, October 2, 2014

Simple IC 555 Touch Activated Switch Circuit

An LED with a suitable series resistance may be included in the circuit and placed in the centre of the touch plate to indicate when the relay is activated. In cases of severe stray pick-up, the unit should be enclosed in a metal casing that should be grounded.
In the circuit, some special precautions have been taken to avoid interference pick-up, to which TTL ICs are especially prone.
To minimise stray pick-up, the interconnections should be as short as possible.
Capacitor C2 is rather large compared to the conventional value (0.0lp.F) used in this position. This modification has proved quite effective.
The power supply shown provides an appropriate DC voltage to drive a conventional relay.
The value of Rl is best chosen by trail and error, and is a compromise between sensitivity and immunity from stray pick-up, Its value lies in the range l.8M to IOM. Rl may be excluded altogether.
If the unitis situated away from the touch sensor, a shielded wire should be used for the connection.
Tl acts as an inverter and converts a rising edge into a falling edge. Transistor T2 is used to provide sufficient drive capability to drive the relay. The external load is connected across the g relay contacts.
An additional decoupling capacitor ((0.0lp.F) may be added as close as possible to the supply terminals of IC 7493. The prototype was constructed on a conventional bread- board.
The circuit basically comprises a touch activated mono- stable vibrator using an NE555 IC, which activates the ITL s 7493 IC used as a bistable. , .
Another modification is the addition of Cl-Rl parallel combination.
The monostable is touch activated and it provides the triggering input to the bistable. However, the bistable triggers only on the falling edge of the monostable output pulse.
This causes a time delay before the load is actually activated. To avoid this, Tl is introduced.