Help with digital counter circuit

ArakelTheDragon

Joined Nov 18, 2016
1,366
The setting of the board are wrong (meaning the circuit settings).

Can you check if timer 555 is working, can you change it to work every second or so, after the timer is working and the second counter ICs get clocked properly, than something on their pins is not connected well. You should check what should the pins be connected to and is there a need for pull up resistors because something is open drain/collector.

EDIT: I am pretty certain that the counter ICs are not well configured because they output "high" on all pins all the time. I had this problem before and I was wondering and wondering and wondering what is going on, everything seemed to work properly but I get only "8ths"........
 

Thread Starter

Mike Baker

Joined Aug 31, 2017
148
The first thing I notice is that the 'clock inhibit' inputs are left floating. I don't know what effect that would have but, in general, CMOS inputs should not be left floating. Connect these three inputs to 0V and see what happens.
Success!!

Thanks albertHall you were correct, I connected pins 2 + 8 on each IC together and Pin 2 on IC1 to ground and its alive and working.

The only problem was that the digits were the wrong way round so it didnt make any sense as started counting on the left.

A quick rewire sorted this.

Thanks to everyone for all their help!!!!
 

WBahn

Joined Mar 31, 2012
32,823
Valuable lesson learned -- NEVER leave inputs to logic gates floating (unless the data sheet specifically says it is okay to do so).
 

Thread Starter

Mike Baker

Joined Aug 31, 2017
148
Is there a way to add a delay to this?

When connected to the press it is double counting. once when the button is pressed and once when the button is released.

Thanks
 

Thread Starter

Mike Baker

Joined Aug 31, 2017
148
Hi Albert, it made no difference...

When the press is powered up and i press the button it still counts twice.

When the power is off and i press the button it counts in multiples of 10??
 

AlbertHall

Joined Jun 4, 2014
12,625
When the press is powered up and i press the button it still counts twice.

When the power is off and i press the button it counts in multiples of 10??
What do you mean by "when the power is off" - you can't mean the power to this counting circuit.

You don't show any supply decoupling in your circuit and this may be the problem. Put a 100uF and a 100nF across the power rails in your circuit.
 

Thread Starter

Mike Baker

Joined Aug 31, 2017
148
What do you mean by "when the power is off" - you can't mean the power to this counting circuit.

You don't show any supply decoupling in your circuit and this may be the problem. Put a 100uF and a 100nF across the power rails in your circuit.
Any chance of a sketch as how to connect the caps?
 

AlbertHall

Joined Jun 4, 2014
12,625
Any chance of a sketch as how to connect the caps?
Not the prettiest diagram but I hope you get the idea. There is a 100uF across the battery, then a 100nF connected closely to the '555 power pins. There should also be a further three 100nF closely across the power pins of the counters not shown on the diagram. As you already have the PCB, you will probably need to 'bodge' these onto the back of the board. Keep the wires to the 100nF as short as possible in preference to making it pretty.
upload_2017-8-31_8-47-54.jpg
 

Thread Starter

Mike Baker

Joined Aug 31, 2017
148
Not the prettiest diagram but I hope you get the idea. There is a 100uF across the battery, then a 100nF connected closely to the '555 power pins. There should also be a further three 100nF closely across the power pins of the counters not shown on the diagram. As you already have the PCB, you will probably need to 'bodge' these onto the back of the board. Keep the wires to the 100nF as short as possible in preference to making it pretty.
View attachment 134439
Thanks I will give it a go
 

AlbertHall

Joined Jun 4, 2014
12,625
They help to remove spikes on the supply caused externally (the clicker press or other such machinery) or internally when the chips switch and draw a pulsed current. The idea is to prevent such spikes interfering with the normal operation of the circuit. It is pretty standard. In the days of TTL the power pins were pretty standard and you could get IC sockets with the capacitor built in.
 
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