Version 4: Scare LED display
Electronic
555, 4017
Controlled by a 555 timer at 5kHz. Counter 4017 has ten outputs. Only six output are needed (Q0-Q5).
The Q6 is connected to the reset (MR Mater Reset). We have 4 groups of diodes.
The diode A which is connected to the outputs Q1, Q3 and Q5.
The group of diodes C are connected in series and the outputs Q2, Q3 and Q4.
The group of diodes D are connected in series and at the output Q4 and the diodes of the group B are connected in series to the output Q5-9.
Which gives as display the following combinations:
Output of |
number |
Del ●= On |
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A |
B1/ B2 |
C1/ C2 |
D1/ D2 |
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Q0 et Q5-9 |
2 |
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Q1 et Q5-9 |
3 |
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Q2 et Q5-9 |
4 |
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Q3 et Q5-9 |
5 |
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Q4 et Q5-9 |
6 |
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●● |
Q5 |
1 |
● |
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B2 |
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C1 |
D2 |
A |
D1 |
C2 |
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B1 |
1 |
2 |
3 |
4 |
5 |
6 |
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Required parts :
• resistors: 330 × 3, 470, 10k × 3 |
• 555 timer IC, Ex. NE555 |
• capacitors : 0.01μF, 0.1μF |
• 4017 counter IC |
• diodes: 1N4148 × 6 |
• Support de circuit IC: 8-pin, 16-pin |
• on/off interrupter |
• LED: Red 5mm diameter × 7 |
• Pushbutton |
• battery clip pour 9V PP3 |
• strip board (Vero board): 20 rows × 22 holes |
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To make a diagram with a logic circuit simulator the diodes are replaced by OR gates and the 555 by a pulser which gives :