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Digital
Dice with Numeric Display
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circuit described here is that of a digital dice with
numeric display. Timer IC 555 wired as an astable multivibrator
produces pulses at about 48 kHz rate. These pulses are
fed to pin 14 of the decade counter IC 7490. The oscillator
is activated by depression of switch S1. Using different
connections for pins 2, 3 (reset to zero inputs Ro(1)
and Ro(2)) and the binary output pins 12, 9, 8 and 11
of IC7490, various count ranges can be set. For the given
circuit the count range is set as 0 to 5 by connecting
QB and QC outputs to Ro(1) and Ro(2) inputs, respectively.
At the count of 6, QB and QC outputs of IC2 go high and
counter is reset. The binary output pins of the counter
IC2 are co- nnected to corresponding input pins of 4-bit
binary adder IC3 (7483) which is wired to give binary
output equal to binary input+1. Thus the output of the
dice ranges from 1 to 6. For obtaining other dice ranges,
reset pins 2 and 3 connections may be made as per Table
I. The binary summation outputs from IC 7483 are connected
to IC4 (7447) which is a BCD to 7-segment decoder/driver.
The output from IC4 is connected to a 7-segment common-anode
LED display (FNDLT312R). When switch S1 is depressed,
the LED (D1) glows and the number displayed at the 7-segment
display changes at a rate of about 48,000 times per second.
As soon as the switch is released, the last (latest) number
remains on display. Thus the circuit performs the function
of a random number generator with the displayed number
lying within the selected (wired) range. |
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