I am trying to learn digital circuits however i got confused in the begining itself. I need some clarification regarding clocks used in circuits, can any one throw some light on the following point:
1. It seems to me that clock circuit is must in digital circuits, is it so?
2. if so, then width of the clock pulse matters?
3. can the function generators out put can be used as clock signal for experimentation? then howmuch should be the voltage level?
aurosunil

 

- not always but very often
- just make it about 50% duty cycle and that should work for now
- depends on logic you want to clock. it should be ok if you
set it to be as high (or a bit lower) as operating voltage of the circuit you are trying to clock. To be sure read the spec for
"0" and "1" for type of digital chips you intend to clock.
For example for most of TTL families, "0" is anything below some
0.8V and "1" is anything above 2.5V. Don't exceed 5V (which is
TTL operating voltage) unless you know what are you doing.
So if you use signal 0.6-2.8V or 0-5V for example, results would
be the same.

 

1. No
2. The width of clock pulse often determine the maximum speed of digital circuits, as they are normally used to clock in data. Having a clock pulse faster than the rated maximum operating frequency of the IC used leads to erratic data outputs.
3. Yes they can. Voltage will depend on the operating voltage of the IC the clock is pumped into.

 

well clock is a must wherever we need synchronization. that is, events that have a fixed time relationship with each other. for example in flip flops and counters we need a clock. that because the counter has to sequence through its specific sequence of states and that has a time factor involved in it. synchronization is a requirement in most of digital circuits, thats why u see clock in almost every digital circuit.

that pulse width doesnt matter that much. it can be anything in edge triggered flip flops. even a clock with 10% duty cycle is sufficient.

yes the function generator can be used as the clock source. the voltage can be read from a digital voltmeter placed across the terminals of the function generator. usually function generators dont have voltmeters built into them because it will read differently for different waveforms. so thats why the measuring is left to the person operating the function generator

 

Thanks all of you however i found that function generator has a TTL out put as well as sine/square wave output. what is the difference in TTL and square wave output? Should not both be same?
aurosunil

 

No - a square wave can be any size, TTL is a specific size squarewave, 5V p-p.

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Hi goodwin!
Thanks for the info.
aurosunil