Project Date: Jun-Mon-29-2015
Project Name: Decade Counter
Decade Counter, using the 7490(LS Type) and 555 timer. You will also see how the LEDs demonstrate the Binary system, and what the result is in Hexadecimal Form.
- 5v Power Regulator
- LEDs (5)
- Resistors: 330 Ohms (5) and 10k (2)
- Capacitor: 47uf (1)
- Jump Wires
- 555 Timer
- 7490 LS Chip
Binary Form – is a mathematical system that includes numeric values represented by 0s and 1s.
555 Timer – is a circuit (chip) used as a timer, pulse generator (electronic circuit used to identify rectangular pulses), and oscillator applicator (generating highly accurate free running waveforms, and stabilizes square wave output waveforms).
Let's Start Building !
Their are two types of counters Monostable an Astable mode. For this project we will use Astable Mode.
First, lets find the frequency by doing a set of equations and having a calculator by your side:
1.44/((10K + 10K *2)*.000047uf)
TL(Time Low)= .693*R2*C
TL = .32571
TH(Time High) = .693 * (RA + RB)*C
= .693 * (10k + 10k) * .000047
= .693 * (20k) * .000047
TH = .65142
D(Duty Cycle) = (R1 + R2)/(R1+2*R2)
= (10k + 10K)/(10k + 2 * 10K)
D = .666666667
Second, attach the timer to the counter.
Hexadecimal #s, base 16, or Hex. Starting 0 to 15 or 1,2,3,4,5,6,7,8,9,A,B,C,D,E,F. For this project we are using 4-bits. The 7490 LS Type counts to 0-9. Every time the timer is on, it will add one # to the counter up to 9 and it will reset to 0.
Every time a LED is on it will equal 1. But when LED is off it will equal 0. If you want examples watch the video above and compare the values with the chart.