Smart Laptop Docking Station with Antitheft alarm

Do you have a laptop docking station, if you have then this circuits can be helpful for you to change it to smart docking station with antitheft alram. You can easily convert yourordinary docking station into asmart electronic laptop dockingstation with antitheft alarm. The following circuits can be used for the design of smart laptop docking station. 

Fig 1: Smart laptop docking station circuit diagram with anti theft alarm

The add-on sensor circuit requiredfor this is built around IC CNY70 (IC1)and IC CD4060 (IC2) as shown in Fig.1. IC CNY70 is an integrated reflectivetypeopto-sensor that contains a phototransistorand an infrared LED. TheLED emits infrared light and the transistorworks as a receiver. The currentflowing through the phototransistordepends on the intensity of the lightdetected.

IC CD4060 is a 14-stage ripple-carrybinary counter. The counter is resetto zero by a gating positive voltage atthe reset input independent of clock.

Power supply to the circuit is derived from AC mains by using stepdown transformer X1. The transformer output is rectified by a full-wavebridge rectifier comprising diodes D1 through D4 and smoothed by capacitor C1. Then power switch S1 is in ‘on’position, the circuit gets power supplyand power-on indicator LED1 lights up. At the same time, the mains socketalso gets the AC mains supply. This mains socket can be used to connect the laptop charger and/or a desktop lamp, etc.

Working of the circuit is simple.

Fig 2: Proposed assembly for electronic smart docking station

When the laptop is in the docking station, the phototransistor inside IC1receives the IR light from the LED, reflected by the laptop surface. The phototransistor conducts to make reset pin 12 of IC2 high, so IC2 does notoscillate.When someone lifts up the laptopfrom the docking station, the photo transistor cuts off and pin 12 of IC2goes low. As a result, IC2 starts oscillating.After a few seconds, delay pin3 of IC2 goes high to drive transistorT1. The piezobuzzer starts beeping toraise an alert and the LED2 glows toindicate that someone has stolen thelaptop from the dockyard.

The simplicity of the circuit makesit ideal for construction on a smallPCB. After completion of wiring, checkthe circuit for proper functioning of allthe sections and enclose the unit in asuitable ABS case. Mount the finishedunit beneath the docking station usingsmall screws/double-sided glue padsso that the opto-sensor is exactly atthe centre of the docking-station baseplate. Refer Fig. 2 for the arrangement.

If your laptop computer is black incolour, it will reflect far less IR light.You can overcome this drawback byattaching a white sticker suitably at thebottom of the laptop.Calibrate the circuit before firstuse. Set preset VR1 at the centre andplace the laptop in the docking station.

Now turn VR1 slowly until IC2 goes tostandby (no-oscillation) mode. Thenremove the laptop from the dockingstation, ensure that IC2 is enabled(pin 12 is low) and wait for the alarmsound. Repeat the process and adjustVR1 until you get the correct result.Note that the LED in the opto-sensor ispermanently powered via resistor R2.Similarly, you are free to experimentwith the values of IC2 timing componentsC5, R3 and R4 for increasing ordecreasing the delay time.