Rab18’s Weblog

This protocircuit setup has moved on from the last protocircuit. On the previous circuit I was able to display three digits and count 0 to 9. The problem I had with this circuit was the numbers were not being displayed clearly.  Other LED’s were lighting up causing the display to read unclear numbers. This is due to the electrons building up at the field effect transistor. This can be rectified by using 10k pull up resistors.

On this protocircuit I have used 10K pull up resistors on each of the inputs to the 4511 BCD. This enables the electrons that have not past through the field effect transistor to pass up through the 10K resistors. When the voltage to the inputs is connected to ground it give no pulse (0), when the connection to ground is disconnected it pulls up through the 10K resistors to the 4.5v giving the inputs on the 4511 a positive charge (1). This gives a much clearer display of the numbers.