Hello everyone!

I came across the following problem. I have created a counter circuit in two different simulators. The circuit is the same in both cases, however I have noticed a difference when I started the simulation. In one of the sims the carry-out pin goes high immediately after the sim is started (power is applied), while in the other the opposite is true, the carry-out stays low when I start the sim.

Clock pulses are not coming in yet, the load input is tied low, and the up/down input (pin 10) is tied low too, since I want a down counter. Which simulator is right? Does the carry-out pin of the 4510 go high when power is applied or does it stay low?

 

No chance to implement that on a breadboard with a slow clock and maybe a scope?

 

Hello everyone!

I came across the following problem. I have created a counter circuit in two different simulators. The circuit is the same in both cases, however I have noticed a difference when I started the simulation. In one of the sims the carry-out pin goes high immediately after the sim is started (power is applied), while in the other the opposite is true, the carry-out stays low when I start the sim.

Clock pulses are not coming in yet, the load input is tied low, and the up/down input (pin 10) is tied low too, since I want a down counter. Which simulator is right? Does the carry-out pin of the 4510 go high when power is applied or does it stay low?

No way to check the datasheet?

 

No way to check the datasheet?

Datasheet says the carry out is high by default and goes low when output is 9 when counting up. It then appears that the next more significant bit increments on the low-to-high transition as carry-out pin returns to HIGH state.

So, to answer your question, the pin does go high on startup.

 

I have tried it on a breadboard. When I completely remove the astable NE555 (clock pulse provider) from the board the carry-out pin has a stationary voltage of 0,07V, which is low as I use a 12V battery as the power supply. When I reconnect the 555 (but inhibit the pulses to reach the clock input) the carry-out fluctuates between 0,14 and 0,08 V and goes high when a carry occurs. So it appears that after applying power and resetting the counter (00:00) the carry-out is at a low logic value (this kind of contradicts the datasheet).

 

I have tried it on a breadboard. When I completely remove the astable NE555 (clock pulse provider) from the board the carry-out pin has a stationary voltage of 0,07V, which is low as I use a 12V battery as the power supply. When I reconnect the 555 (but inhibit the pulses to reach the clock input) the carry-out fluctuates between 0,14 and 0,08 V and goes high when a carry occurs. So it appears that after applying power and resetting the counter (00:00) the carry-out is at a low logic value (this kind of contradicts the datasheet).

Look for the datasheet of your specific part/manufacturer.

 

Okay, I have found out the problem. If you connect the up/down pin to ground (down counting mode) and reset the 4510 to 0 it will count as a carry as carry occurs at 0 to 9, even when there aren't any clock pulses coming in, so the carry-out pin will go low. If you connect the up/down pin to the power rail (up counting mode) and reset the counter to 0 it will not be count as a carry, since carry appears at 9 to 0 transition in up counting mode, and the carry out remains high. All in all, one of the simulators is faulty.

The datasheets were not too helpful, since don't talk too much about the carry-out phenomena.

Thanks for the answers.

 

In the future, post a schematic and names of simulators.

What datasheet are you using? I've looked at a few and some are better than others. All provide a logic diagram so you can analyze carry out behavior.

EDIT: Correct spell checker corrections...

 

In the future, post a schematic and names of simulators.

What datasheet are you using? I've looked at a few and some are better than others. All provide a logic diagram so you can analyze carry out behavior.

EDIT: Correct spell checker corrections...

Funny thing is that they're basically identical. One of them is Circuit WIzard Pro 1.60 the other one is Circuit Wizard 2 Student Edition. The CW 2 SE is the one with the correct carry-out behavior.

 

Sorry, I forgot to post the schematics. This is the most basic circuit that can demonstrate the problem. CW1 is the wrong one and CW2 is the good one, as it can be seen on the multimeters.

 

Yep. Carry out should be high then go low on Carry Out whether you are counting up or down. What is Preset doing?

 

Yep. Carry out should be high then go low on Carry Out whether you are counting up or down. What is Preset doing?

Hi hp1729. Do you want to know what the preset enable pin is doing on the 4510 ic in general, or your question is concerned about my circuit?