Mathemagic – Mind Reader

This is a simple application where in you think of a number from 1-99 in your mind and then the machine tells you what it is !

All you have to do is, think of a number and say if it is greyed out in the series of cards shown.

Before we step into any detail, Watch the video :)



The concept behind this is a BCD to 7-Segment decoder(IC7447). The unit and tens place of the number are in BCD. For example let’s consider the number 24

Number 2 4 – This in BCD would be 0010 0100. Thus this number would be found in sheet3 and sheet6. When you press these corresponding switches, the number would come up in the 7-segment display.

The switches used here are momentary push switches. When the switches are pressed, we would need it to be giving a constant HIGH. For this we use D Flip Flop (IC4013).


Switch Configuration:

The flip flop is used to sense the switch input and it goes high permanently (until the reset button is pressed). For this we connect the ‘data’ pin to VCC and the clock pin to the switch output. As the flip flop is positive edge triggered, this pin is pulled low with a resister and the switch is connected to VCC. When the switch is pressed, the pin is pulled up to VCC and this triggers the flip flop, thus the output pin ‘Q’ goes HIGH.


IC7447 is used to drive the 7Segment. This circuit uses a common anode 7-Segment, the output of flip flops are directly fed to the BCD inputs of the 7segment driver.

Circuit Diagram:

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Let me know your comments :)

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5 Responses to “Mathemagic – Mind Reader”

  1. […] entries Tic Tac Toe won a first place and Mathemagic won a third place […]

  2. Diego says:

    How much volts do you use to power these? And also, can we use CD3013BE instead? And what values of resistor do you use?

  3. Vincci says:

    What is the values of volt you use? And what is the values of resistor? Thanks

  4. Vincci says:

    What are the values of volt you use? And what are the values of resistor?

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