This is an electronic head or tails circuit ,that same really the head or tail playing very little head by following several steps.
-First of all,turn on switch, LED display show digit “0”.
-Secondly, press the button “rotate” then the coins computer will begin rotate, notice of LED1 will be light, wait until LED1 go out.
-Next, select switch S3 to guess “head” or “tail”.
-When guess, then press S4 to “Open”. This circuit to check, if you guess right the score will move up to No. 1 and again 1 step to step. If wrong, all your points accumulated will be lost.
How it works
This circuit is all digital, no transistor. So easy to understand.
– In figure circuit, when turn on S1, IC1-LM7805 as 5V DC fixed voltage regulator to control voltage in level of 5 volts. And apply the power to all IC in this circuit.
-If we press S2, will has volt to charge C1 until state as “1” to IC2/1 and IC2/2 that are connected as the oscillator circuit to generate clock signal to IC3/1.
– Which is delay flip flop that connect the clock signal to the 2 divider circuit at pin 12 and feedback always to pin 13 of IC3/1.
-Then, C1 discharged fully down to “0” then IC2/1 and 2/2 will stop oscillation.
-Cause IC3/1 still display is pin 13 or pin 12 will has signal is “1” into pin 5 of IC3/2.
Choosing correct and wrong.
Assuming that the pin 12 is “1″, and We chose this way fit. cause pin 5 of IC3/2 is also “1” .
– But output of IC2/3 is “0” because connected as the inverter, cause pin 1 and pin 5 of IC4 ©©©© “0”. and when press S4 will makes pin 2 and pin 6 of IC4 is “1”.
-And the same time, pin 3 and pin 4 of IC4 will be also “1” .
-But through IC4/3 and IC4/4, which is connected also to the inverter, cause pin 10 and pin 11 is “0”. so no signal to reset IC5 and feedback to IC3/2.
-When we press S4 will cause pin 1 of IC3/2 is “1”, which 0-9 binary counter circuit.
-When IC5 get signal Clock then convert the binary signal into IC6 which is decoder IC to convert the signal to drive the 7 Segment LED, to show score.
– If wrong pin 5 of IC3/2 will be “0” while pins 8, 9 of IC2/3 will be also “0”, but pin10 of IC2/3 will be “1” cause pin 1, 5 of IC4 is “1”.
-When we press button “turn on” which will cause pin 2, 6 of IC4 is also “1”. Thus at pin 3, 4 of IC4, will be “0” but when through IC4/3 and IC4/4 will cause “1” to reset IC5, cause the output is “0” again.
The parts you need
IC1______LM7805__5V DC voltage regulator
IC2,IC4__CD4011__Quad 2-Input NOR Buffered B Series Gate
IC3______CD4013____CMOS DUAL D-TYPE FLIP-FLOP
IC5______MM74C93_____4-Bit Decade, Binary Counter
IC6______74C48___BCD-to-7 Segment Decoder