What kind of circuits output a number of pulses before it goes into a low state?

[danny davis]

What kind of circuits output a number of pulses before it goes into a low state? what kind of circuit's is this called?

What Component determines the number of pulses? is a counter or clock , or timer the only options?

a.) use a counter , but how do u get the counter to only output 20 pulses before it went into a low state?
b.) use TIMER, but how do u get the Timer to only output 20 pulses before it went into a low state?
c.) What can I use to ENABLE an Op amp input or a Comparator input to only output 20 pulses before it went into a low state?
d.) What can I use to ENABLE a Transistor or FET was a "switch" to only output 20 pulses before it went into a low state?
e.) Use A clock , but how do u get the clock to only output 20 pulses before it went into a low state?

What is an RC network that has Diodes called? the diodes are to discharge the RC network really fast

Can you make an Counter or Timer from an RC network that has Diodes to do the discharging? a Passive RC network with Diodes configured to be a counter or timer? to only output 20 pulses and then it goes into a low state?

Example#1 circuit
Pulse period = 1 second
Number of pulses = 20 pulses = 20 seconds
Total time of pulse train = 20 seconds
Output goes into low state after 20 seconds

 

[andre_luis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

It is possible to do everything as we need with passive and active components without use of a programed unit, such as a microcontroller.
What you are asking for sounds as a train pulse modulated by a monostable.


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[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

train pulse modulated by a monostable.

What do u mean by modulated?

How can a monostable control the number of pulses in the pulse train?

 

[andre_luis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

Before attempting to implement any solution for circuit, I'm just trying to synthesize the concept of what exactly you need to do.
As I understood, it seems you are trying to implement a generator pulse train one shot, that's right?


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[betwixt]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

Andre_teprom, read this persons other posts, they are not familiar with basic electronic and logic concepts - you have to make your answers VERY simple!

Brian.

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Danny, please think about that question - it appears you are asking for something that produces 20 pulses then goes low. So what does it do between the pulses? If there are 19 gaps between them, what happens during the 'gap' time?

The professional name for an RC network with diodes is "an RC network with diodes". If you are asking what the diodes are for you will have to explain how they are connected to the RC network.

Brian.

 

[andre_luis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

...read this persons other posts, they are not familiar with basic electronic and logic concepts - you have to make your answers VERY simple!

Agree with you, and the first attempt is to understand his demand, once he´s describing the need from components functionality, and this approach seems as designing solution from end, instead from design requirements.




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[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

for something that produces 20 pulses then goes low.

Yes what kind of circuits do this?, where have u seen them? and what kind of a circuit is this called? it doesn't have to be the same number of pulses but does the same job and functionality

So what does it do between the pulses?

What do u mean? it's a pulse train, the pulse period is 1 second , it's a squarewaveform

What else can it do between pulses? besides go to a LOW state?

If there are 19 gaps between them, what happens during the 'gap' time?

It's a low state, what else can happen in the "gap time"?

 

[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

When a counter, timer or clock outputs a pulse train and doesn't stop , is this called free running? i don't know the correct term
When a counter, timer or clock outputs a pulse train but STOPS at a certain number of pulses, what is this called? i don't know the correct term

 

[betwixt]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

For someone who refuses to accept Ohms law you now ask questions about digital pulse generators.

To answer your question:

1. You need a clock source to generate the pulses and gaps between them.
2. You need a counter circuit to detect and count the number of falling edges on the clock waveform.
3. You need a gate to pass the clock to the output point only when the counter has not reached terminal value.
4. You need a reset circuit to allow the count to be cleared and restarted if necessary.

Another less accurate method:

1. You need a clock source to generate the pulses and gaps between them.
2. You need a monostable circuit with trigger synchronized to the clock and period equal to 20.5 pulse lengths.
3. You need a gate to pass the clock to the output point only when the monostable is in it's active state.
4. You need a reset circuit to force the monostable back to it's pre-triggered state.

It doesn't have a name, it's just a sequence of 20 pulses.

Brian.

 

[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

Thanks for the info

To answer your question:

1. You need a clock source to generate the pulses and gaps between them.
2. You need a counter circuit to detect and count the number of falling edges on the clock waveform.
3. You need a gate to pass the clock to the output point only when the counter has not reached terminal value.
4. You need a reset circuit to allow the count to be cleared and restarted if necessary.

Another less accurate method:

1. You need a clock source to generate the pulses and gaps between them.
2. You need a monostable circuit with trigger synchronized to the clock and period equal to 20.5 pulse lengths.
3. You need a gate to pass the clock to the output point only when the monostable is in it's active state.
4. You need a reset circuit to force the monostable back to it's pre-triggered state.

In both examples, what is determining the 20 pulses? is it the reset circuit? how does it know to only output 20 pulses?

Can a RC network with or without diodes generate a pulse train?, or pulses with gaps?
Can a RC network with or without diodes that's connect to a comparator generate a pulse train, or pulses with gaps?

 

[Audioguru]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

Danny, why didn't you learn ANYTHING about electronics?
A counter is usually BINARY but some count in BCD. It has many outputs.
You need a DECODER to detect the 20th counter output. A gate or a bunch of gates can be connected together to decode "20" or any other number you want from the outputs of a counter. A CD4017 has a counter and decodes 10 sequential outputs.

An RC network with or without diodes is passive and cannot generate anything. An oscillator with or without diodes can generate a pulse train. An RC network can filter the pulses in a pulse train.

 

[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

I mean an RC TIMING network sorry not an RC network lag or lead for frequencys

 

[Audioguru]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

An RC network can be used for the timing of the frequency of the OSCILLATOR that makes the clock pulses.

 

[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

An RC network can be used for the timing of the frequency of the OSCILLATOR that makes the clock pulses.

Yes I know that

Can a RC network with or without diodes that's connect to a comparator generate a pulse train, or pulses with gaps? or clock pulses

 

[andre_luis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

...Can a RC network with or without diodes that's connect to a comparator generate a pulse train...

Surely, but you need some other few components, such as a 555-like device and maybe 1-2 logic gates...


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[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

I'm trying not to use a clock, timer, or counter

Just an TIMING RC network, comparators , maybe logic gates or a transistor as a switch

The comparator can ENABLE the transistor switch to turn it off and on, but how can i only get 20 pulses?

The Timing RC network is the pulse width or the pulse period?

 

[andre_luis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

If you take a look inside LM555 device model, will realize an arrangement compound for a comparator and a logic circuit.
Could be a start to you design your circuit based on discrete components:



Take a look on Application Notes of that device to help you design the final circuit.






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[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

True, you're right

The RC timing network have a charge time and discharge time, both are different from eachother which creates a duty cycle 60% , 40% ratio

Does the RC timing network set the pulse width or pulse period?

The timing gaps are caused by the comparator turning off and on , them the input threshold

 

[andre_luis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

...Does the RC timing network set the pulse width or pulse period?...

Both charge and discharge timing are strongly dependent.
What change you performs at one will impact on another, so that you have a limited range to modify duty-cycle.


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[danny davis]

Re: 20 pulses and circuit goes LOW state, what determines the number of pulses

Both charge and discharge timing are strongly dependent.
What change you performs at one will impact on another, so that you have a limited range to modify duty-cycle.

Yes true

Duty cycle is the charge time and the discharge time ratio = the pulse period
RC network Pulse width = is the Charge time
RC network Time gap = is the discharge time

I think the FEEDBACK loop inside the 555 time is what RESETS the RC network , without the FEEDBACK loop, there would be no pulse train output

What circuit can i put on the output of the 555 timer to counter the pulses and to shut off after 20 pulses?