25-08-2017, 09:32 PM
Multichannel code lock system
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This project is code based electronic locking system to control the operation of several appliances the circuit uses a three decimal coding system.
For operating any appliance. Thus, for each appliance a unique three digit code, from numbers 101 to 999, is selected.
Although this circuit can be used to controls many as 999 appliances. I am just adding only three appliances more devices can be added as per requirement. Additional devices can be added via 10 pin connectors provided. For the operation of each appliance a manually operated appliance specific toggle switch is turned on prior.
To the selection of the appliance code. The code selection is done through three push to on switches, with each one associated with a specific digit. The
selected number is displayed on three segment display for a short time. On selection of any appliance, the counter and the displays are automatically reset. However the selected appliance stays on due to latching action of the relay through a pair of own contacts. A fresh selection is accompanied by a short-duration musical note arrangement of manual resetting of counters and display is also included.
The circuit consists of a 555Ic (IC1) which is wired as an unstable multivibrator with 50% DUTY CYCLE and a clock period of one second. The output of ic1 is used as a clock for CD4033 decade counter cum display driver ICs(ic2 , ic3 ic4 )and cd 4017 Johnson ring counter ICs IC5, ic6 ic7. In fact the clock to the pairs, formed by ic2 plus ic5. Ic3 plus ic6 and ic4 plus ic7 is routed via push to on switches S1 S2 S3 respectively.
The three sets each comprising a CD4033, a CD4017, and a seven segment display, function independently with the rest pin 15 of all CD4017 and CD4033 ICs tied together. ON reset only the Y0 outputs of ring counter ICs (CD4017) are high while all other outputs (Y1 to Y9) are low. At this instant the output of all CD4033 counters would also correspond to zero count and thus the display would show 000.
The outputs of CD4017 (IC5, ic6, ic7,) are connected to the input of three input AND-gate, N1 N2 and N3 inside IC8 CD4073. Depending upon the desired code for any given appliance’s operation. One can make corresponding connections from the outputs of CD4017 ICs to the AND gate used for controlling the operation of the specific appliance .For example if device one to be open with the code 794, than connect outputs Y7 of IC5 Y9 of IC6 and Y4 of IC7. To the output of gate N1 is connected for control of appliance 1 through high- Darlington array ICULN2003 (input pin 2 and output pin 15) to DPDT relay RL1. When relay RL1 energizes, assuming switch S5 is in ON position, The relay gets latched as it receives the positive supply via the switch and ground via one of its N/O contact. Thus once an appliance is operated after its corresponding switch and code have been correctly selected, it can be switched OFF manually by flipping its corresponding switch (S5, S6, or S7) to OFF position.
Similarly, for control of other appliances, outputs of AND gates N2 and N3 are connected to input pins 3 and 4 of relay driver IC ULN2003, and its output pins 14 and 13 are connected to relays RL2 and RL3 respectively. External free-wheeling diodes are not required across relay coils because are built within the ULN2003 IC itself.
The circuit incorporates automatic reset arrangement. The output of all AND gates are connected in wired or fashion to pin 1 of ULN2003IC by making use of diodes D2 through D4. Thus output of any AND gate goes high. This cause its pin 16 to go low and energise relay4 which in turn causes the positive supply rail to be extended to the common reset line of all counter ICs (IC2 through IC7). Once the counter get reset the AND gates output falls low and R4 is de-energised. Simultaneously the display also returns to show (000) since the counter has been reset. Resetting of the counters and display does not, however, effect the operation of any appliance because of the latching action of the relay.
Also when the circuit is reset automatically, it produces a musical tone for about 5 seconds to indicate that some appliance has been switched ON. As mentioned earlier pin16 of IC, UM2003 goes low momentarily to automatically reset the counters through operation of RL4. The high-to-low going transition at pin16 of IC, UM2003 is also passed to trigger pin 2 of time4r IC 555 (IC10) which is configured here as a five second monostable flip-flop. The output of IC10 is counted to musical tone generator IC, UM66 (IC11) which generates a musical tone for the five second duration of the monostable pulse output. The code is entered using push to ON switches S1, S2, and S3. Incase wrong code gets entered, you can re-enter the correct code after restarting the circuit manually, by pressing the reset switch S4. During manual resetting, the system will not produce any musical tone. During re-set. A logic high level is applied to the pin 15 of all counter counter/seven segment driver ICs. In normal case these reset pins are at a logic-low state.
The circuit shows the connection of the three appliances having code (794), (969), (337) respectively. To operate the first appliance, reset the counters by pressing S4 momentarily. Flip S5 to ON position. Now press S1 as soon as display 1 displays 7 similarly press S2 and S3 for second and third digit of the code. The other all devices can be controlled similarly.
For control of additional appliances just add additional gates ULN2003 arrays, relays and switches the input for additional gates can be obtained from the from the outputs of CD4017 ICs terminated on counters as shown in the schematic since these CMOS devices have a high fan out capability (about 50 devices) we can a large number of AND gates without degrading their performance. Each device is to be allocated a unique code between (001 and 999) decimal. If you desire to expand the code, we may do so by just adding the sets comprising ICs CD4017, CD4033, and a seven segment display. The AND gate used should have the same input (or greater capacity) as the number of sets/digit.
APPLIACATIONS
This multichannel code lock system can be used to control (999) Appliances with each having a unique code for its operation.
To switch any one of the connected devices can be switched ON by entering the correct code for turning it ON.
It can be used with the devises which need a security eg. You don’t want to allow anybody to switch ON the devise without your wish.
It can be used f0or controlling the home appliances like fan, motors, any such device which need to be switched for its operation.
Any electronic, electrical, and electro-machinical device be controlled by connecting it through the code lock system.
Tom turn the specific appliance ON the accurate three decimal code must be entered.
This code lock system can be used for home appliances
As most of the kids and even children mostly have a habit to switch the buttons of fan and lights for fun which may cause any damage to the devise or it may cause a serious shock to the kid. To avoid this type risks if the devise is controlled and connected to the code lock system than normally there is no power flowing in the switch this can be turned ON only by entering the correct code allocated to the device.
Even this can be used