Saturday, December 19, 2015

Multisim| Stopwatch Timer Cascading 7 Segments 74ls190 74ls47

Stopwatch Timer Cascading 7 Segment Displays

Written by Larsha Johnson
12/19/2015

In this blog a stopwatch is simulated in Multisim and converted to a PCB layout via Ultiboard

Build of material:

  1. Two 7 segment displays
  2. Resistor packs (100 Ohms) *included in updated model
  3. Two 74ls190 (up/down counters)
  4. Two 74ls47 (BCD decoder)
  5. 555 Timer (1MHz digital clock in Multisim)
  6. One toggle switch (up/down)
  7. 1 Tact push button switch (reset)


You will need: 
automatic_7_seg_counter.ms14
Download File



Seven segments are everywhere, clocks, elevators, microwaves, cars, etc.

To connect the 7 segments, match A-G segments to the pins of the decoder according to the datasheet. RI, BI, LT should be connected to VCC.
The 74ls190 can be preset to a specific start time.

Seven segments and decoders are one of the most common types of parts I used to build circuits during my first years studying Computer Engineering Technology. Knowing the difference between anode and cathode use to be a task as well as knowing which type of decoder to use. Now that I have played around with them I am able to build more circuits using the two. 


As a beginner you may want to try this 7 Segment Counter project. In the video you will see how I designed an up/down automatic counter and the list of parts I used. 

Snippet for drag and drop coming soon.
*Visit our Git page for free files. https://github.com/Bits4Bots

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