I have to design the digital part of a pulse meter.
The output from th analog comparator is a pulse with amplitude of 4.895V and Frequency 16.108Hz.
This pulse is then fed into a D flip-flop and gated with a 555 timer circuit with a 1KHz frequency.
I need to simulate the above but cannot find a suitable simulator which has the LM555. I am using Tina simulator, though it has the LM555, its not working as expected. Please note: R1 = R2 = 1KOhms and C=481nF..though i should use practically available components, I want to see the output of the circuit in simulation first and then go on to PCB design.

Please please please advise if there is a need to change component values or any alternative simulators.

Thanx much!

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Please post your schematic.

Ken

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Although using a 1kHz oscillator shouldn't make any difference. Have you tried the NE555 which is exactly the same part?

What's going on with the LM311? It's output is just connected to +V which will short circuit when the output transistor goes on.

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I dont see any change in the comparator output when the short circuit is removed...well, I cannot say the reason why this has been done, I have been given the circuit at Uni and since I am only in charge about the gating/control part, it doesnot matter. :-)
I am not supposed to use any other timer, since the only 555 timer to be available for the PCB is the LM555..i tried using Tina simulator, got some quite expected pulses...but there is a large delay and i got to explain why is that?
This is kinda frustrating since Im having these problems right in a simulator(where every component is considered ideally)..I wonder what will happen in building the real thing,the PCB!

Please give me any idea about the 555 and the gating.

thank you very much!

 

I think you should check the LM311's data sheet. The comparator's output (pin 7) is the one that comes off the point of the triangle. The strobe (pin 6) is the one that you have connected to R1 and are using for the output.
Ken

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"To invent, you need a good imagination and a pile of junk."
Thomas A. Edison (1847 - 1931)

 

ok, i changedthe pins in SIMetrix simulator..there is no change in the comparator output.
i mean we r still obtaining the exact expected output from the comparator, where in this case its a 16Hz pulse with 4.86 V amplitude which then clocks the D flip flop..the problem here is to obtain an exact 1KHz 555 timer clock pulse in simulation.

 

The old 555 was invented long before simulation was thought about.

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Uncle $crooge

 

There is not change in the comparator's output because you've got the darn thing shorted to VCC. Connect the output to VCC via a pull-up resistor like the datasheet shows you and you should see a change in the output.

There is no need to simulate the 555, it will work, providing you build the circuit correctly, just throw in the required values of R and C and it'll do what you want.

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Screen name: Aloone_Jonez
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