Friday, August 15, 2008

decade counter and display circuit driven by a 555 timer


Gomaiz said...

I was here :D,
Mostafa Magdi

Anura said...


I Really hope you could help / advice me with my project.

I have to create a car that will pass thru 9 stations overhead bridges. The car has a LDR on the top. The car will start at
station 1 and pass thru till station 9. When the car passes thru each station, it will count up till 9 (getting trigger signal from
the LDR). Once it reaches station 9, it will send a signal to the motor driver circuit (See picture (Pin J8 connected to a relay))
which will cause the car to reverse and it will need to countdown as goes back to station 1.

I have the following circuit’s boards:

LDR Circuit

Motor Driver & Power supply (9V to 5V)

UP/DOWN Counter (74LS193) to BCD (74LS47) to 7 Seg display

Here is the overview picture of the whole circuit:

** I need to creat a circuitry that will do the above function. **

The components I can use are:

74LS32 OR gate
74LS08 AND gate
74LS04 NOT gate
74LS02 NOR gate
74LS00 NAND gate
74LS74 D flip flop
2N3904 NPN transistor

I hope and appreciate you are able to help as i really lost. Thanks alot!!!