Back and Forth Flasher
by Tony van Roon
1-to-16 Demultiplexer - Selected output is low when Data IN is low. If Data IN is high, then selected output is high also. Each 4-bit address drives one output low. All others stay high. Enable inputs (E1 & E2) must be low. If one or both are high, all inputs go low.
An error was found by Martin in regards to two pin 3's on the 74LS193. Corrected! Pin 6(7400) goes to pin 5 of the 74LS193. Thanks Martin!
Parts List
U1 = SN74154 (demultiplexer)
U2 = LM555 (timer)
U3 = SN74LS00
U4 = SN74LS190
P1 = 100K
R1 = 1K
R2 = 470-Ohm
C1 = 0.33uF(tantalum)
16 LED's, high brightnes or ultra-bright
Table 1 - Connection Scheme
| Pos |
IC |
Pin # |
La # |
Color |
Wir |
Wire |
| 1. |
74154 |
Pin 1 |
Led 1 |
Green |
Or |
Orange |
| 2. |
74154 |
Pin 2 |
Led 2 |
Yellow |
Whi |
White |
| 3. |
74154 |
Pin 3 |
Led 3 |
Yellow |
Blu |
Blue |
| 4. |
74154 |
Pin 4 |
Led 4 |
Red |
Blk |
Black |
| 5. |
74154 |
Pin 5 |
Led 5 |
Red |
Rw |
Red/White |
| 6. |
74154 |
Pin 6 |
Led 6 |
Red |
Gw |
Green/White |
| 7. |
74154 |
Pin 7 |
Led 7 |
Red |
Bw |
Blue/White |
| 8. |
74154 |
Pin 8 |
Led 8 |
Red |
Bw |
Black/White |
| 9. |
74154 |
Pin 9 |
Led 9 |
Red |
Or |
Orange/Red |
| 10. |
74154 |
Pin 10 |
Led 10 |
Red |
Br |
Blue/Red |
| 11. |
74154 |
Pin 11 |
Led 11 |
Red |
Bkr |
Black/Red |
| 12. |
74154 |
Pin 13 |
Led 12 |
Red |
Rb |
Red/Black |
| 13. |
74154 |
Pin 14 |
Led 13 |
Red |
Bb |
Blue/Black |
| 14. |
74154 |
Pin 15 |
Led 14 |
Yellow |
Gb |
Green/Black |
| 15. |
74154 |
Pin 16 |
Led 15 |
Yellow |
Pi |
Pinkk |
| 16. |
74154 |
Pin 17 |
Led 16 |
Green |
Pu |
Purple |
| 17. |
Gnd |
12/18/19 |
Common |
to everything |
Gnd everything |
Green |
| 18. |
Vcc+ |
24 and |
anodes |
5.5V to 7.5V |
Re 5 - 7.5 V |
Red |
| 19. |
n/a |
|
|
|
|
|
| 20. |
n/a |
|
|
|
|
|
| 21. |
n/a |
|
|
|
|
|
| 22. |
n/a |
|
|
|
|
|
| 23. |
n/a |
|
|
|
|
|
| 24. |
n/a |
|
|
|
|
|
A Couple of Final Notes
Click here >>LM555 << for more information and data on the 555 timer/oscillator IC. Keep wires as short as possible since too long wires coming from the 74154 to the led's will give trouble getting them 'running' properly. I had this circuit installed in the nose of my helicopter before I sold it and the circuit was working good. This circuit is for those electronics persons with experience only. In either case, it is definately a good learning experience. Have fun!
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Copyright © Tony van Roon 1993-2001