/People-counter-74xx

Simple board with LED displays, decade counter, BCD to 7-segment decoder and input for sensor (e.g. PIR, laser...).

MIT LicenseMIT

FI-MUNI_People-counter-board

Czech documentation

Simple board with LED displays, decade counter, BCD to 7-segment decoder

Simulation of circuit in Every Circuit:

Parts

  • 4× 74LS90 - Decadic BCD counter (datasheet) - can be purchased MyArduino.cz or Farnell.com
  • 4× 74LS47 - Decoder BCD/7segm. (datasheet) - can be purchased MyArduino.cz or Farnell.com
  • 4× 7 seg. display HD-A554RD (datasheet) - can be purchased GME
  • 31× resistor 220 Ω v package SMD0603
  • 1× resistor 10 kΩ v package SMD0603
  • 2×2 a 2×4 90 degree pinheads 2,54 mm
  • 1× MicroUSB connector - can be purchased Mouser or Farnell

Parameters

  • power supply: 5 V over pinheads or microUSB connector
  • consumption: approx. 200 mA
  • size of PCB: 70 × 69 mm

Versions of PCB - bugs and modification

v1.0

  • wrong value of the capacitor C2 near IC 555: 10 uF -> 200 nF
  • wrong net to the potentiometer R29 -> delete this net in v1.1 or modify the R29 (cut off one pin on R29)

v1.1

  • fix bugs from v1.0

Photos

PCB with all parts People-counter-74xx_off_top.jpg

PCB in operation People-counter-74xx_v1.0_on_top.jpg

PCB with USB power supply and PIR sensor People-counter-74xx_v1.0_on_with-sensor.jpg