Scoring game circuit

Description.
A simple scoring game circuit that can be used for all occasions when a dice is needed.The circuit is based on a NE555 timer,a 74LS192 counter,a74LS247 decoder and a & segment LED display.The timer IC1 will produce the clock for the counter IC(IC2) whose frequency is determined by R1 and C2.When S2 is pressed the IC2 will count in up mode and when S3 is pressed the IC2 will count in down mode.The IC 3 will decode the count to display it on the seven segment LED display .Thats about the working of the circuit.The circuit is designed strictly sticking on to the basics of counters and is a good one for beginners.There is nothing big deal.
Circuit diagram with Parts list.

Notes.

• To play the game switch the power ON and press S1 to reset the counter.
• Now press S2 or S3 and release .The IC2 will hold the last count .Now press S4 to see the score on display.That’s your score.Now the second person can try.
• Each time one tries, he should press the S1 to reset the count and then press S2 or S3 and then S4 to see the score.
• Circuit can be powered from a 9V radio cell or a 9V regulated DC power supply .

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Digital code lock

Description.
This is a simple but effective code lock circuit that has an automatic reset facility. The circuit is made around the dual flip-flop IC CD4013.Two CD 4013 ICs are used here. Push button switches are used for entering the code number. One side of all the push button switches are connected to +12V DC. The remaining end of push buttons 2,3,6,8 is connected to clock input pins of the filp-flops. The remaining end of other push button switches are shorted and connected to the set pin of the filp-flops.
The relay coil will be activated only if the code is entered in correct sequence and if there is any variation, the lock will be resetted. Here is correct code is 2368.When you press 2 the first flip flop(IC1a) will be triggered and the value at the data in (pin9) will be transferred to the Q output (pin13).Since pin 9 is grounded the value is “0” and so the pin 13 becomes low. For the subsequent pressing of the remaining code digits in the correct sequence the “0” will reach the Q output (pin1) of the last flip flop (IC2b).This makes the transistor ON and the relay is energised.The automatic reset facility is achieved by the resistor R11 and capacitor C2.The positive end of capacitor C2 is connected to the set pin of the filp-flops.When the transistor is switched ON, the capacitor C2 begins to charge and when the voltage across it becomes sufficient the flip-flops are resetted. This makes the lock open for a fixed amount of time and then it locks automatically. The time delay can be adjusted by varying the values of R11 and C2.

Circuit diagram with Parts list.
Notes.

• Assemble the circuit on a good quality PCB.
• The circuit can be powered from 12V DC.
• Mount the ICs on holders.
• The L1 can be a 12V, 200 Ohm SPDT relay.
• Capacitor C1 should be tantalum type.
• The C1 and C2 must be rated at least 25V.

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Combination Lock

D-type bistables can easily be used to make a combination lock. Using two 4013 integrated circuits, you can make a 4-digit combination lock in which the keys representing the code digits must be entered in the correct order. Pressing the key for any digit which is not part of the code RESETs all four D-types:

The D-input of the first D-type is held HIGH. When the first digit of the combination is pressed, output Q goes HIGH. If the second digit is the next key presssed, the second D-type will be SET and so on. Pressing any of the unselected keys gives a HIGH at the RESET inputs of all four bistables, and all the Q outputs revert to LOW.

Once the four digits of the code have been entered in the correct sequence, the lock ouptut goes HIGH and will remain HIGH until an unselected key is pressed. The system could be extended to provide an automatic RESET after a delay. Which type of subsystem could you use?

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