Hey guys,
I dont know where to open this topic since i am beginner in this forum and i dont know how to ask this question but here goes nothing.
First of all i have a project which i want to make upgrades on it and i have an idea. I am using a shift register and i want to increase its clock speed when some specific thing happens and also revert it to its previous speed back when another specific thing happens. This specific thing is like this, i have an input with switch lets call it input B and i have an input which is an output of shift register that i use lets call it A. When B gets from 0 to 1 or 1 to 0 the clock of the register must increase its speed, untill A gets to 1 (if it was 0 before) or A gets to 0 (if it was 1 before). So when there is change in B circuit starts and works untill there is a change in A, how can i build a circuit like that with using IC's?
Thank you.

 

What is the clock source?
What change in clock speed do you need, from what frequency to what frequency?
How exact do these frequencies need to be?

 

Shift register's clock is normally connected to a 555's output which is 2 hz. When specific thing happses, I want to increase shift register's clock 50 hz, and probably this will be done with using another 555.

 

You could have one 555 and use a P-MOSFET to switch in a different charge resistor value to increase the 555 frequency.

Post a schematic of your 555 circuit.

 

This is basically my 555 (PS: VCC and RCT are connected to 9v, and GND is connected to ground i wanted to write since its not shown in the picture), i didnt set it to 2hz yet but i will soon with changing capacitor or resistors depending on what i have (i will make this on breadboard as well). So i didnt wanted to use a transistor since i dont have any knowledge about how these things work. But still my main problem is to make a circuit which operates when an input changes and reverts itself back when another input changes.

 

So what is the input signal change that will be used to change the 555 frequency?
Is it an analog or digital signal?
What is its voltage?

If you don't understand transistors, what logic families are you using?
Do you use CMOS CD4000 devices?

 

We dont have to change 555's frequency, it will be better if i use a second 555 (which is 50 hz) and make circuit switch between the 50 hz one and 2 hz one. Also my inputs are both digital. both of them are 9v when high. I am using 7400 family IC's.
So my circuit should work like this, at the start B has a button to make it either 0 or 1. When circuit starts it can be either 0 or 1 and my shift register starts to work with 2hz clock. When user presses that button they will make B 0 (if its 1 at start) or 1 (if its 0 at start) and both of these changes will trigger the 50 hz 555, and i want this to change my shift registers clock with 555 which gives 50 hz as output. Now my A input is also an output from my shift register (which is also digital) and when A changes from 0 to 1 or 1 to 0 i want shift register to switch its clock to 555 which gives 2hz as output.
Thanks.

 

my inputs are both digital. both of them are 9v when high. I am using 7400 family IC's.

7400 series TTL is 5 V logic. 5 V only.

ak

 

So i will change my it to 5 volts. Thanks for reminding, things do work fine on multisim but i might have blown up some circuits if i was tried it with 9v at breaboard.

 

While original TTL is 4.75 to 5.25, some of the CMOS TTL-equivalent stuff is a little wider. I believe 74HCxx is 3 V to 6 V, but I don't think anything with 74 in the number has the full CMOS 3 V to 18 V range.

ak

 

I don't think anything with 74 in the number has the full CMOS 3 V to 18 V range.

The 74Cxx series does.
It appears to basically be the same CMOS process voltage and speed as the CD4xxx series but with the 74xx functions and pinouts.

 

So do anyone have an idea how i can do a circuit like i mentioned above?

 

Do you have an idea of how much information you have *not* given us to work with?

Block diagram of your concept so far?
More complete schematic?
Is the "switch" a mechanical device, like a toggle or pushbutton?
Does the shift regiser clock get faster and faster each time the switch is activated?
What are the highest and lowest shift register clock frequencies?
Does the shift register have to be cleared to all zeros when power comes on?
It sounds like the shift register has a serial output. Is the input serial or parallel?
What is the input to the shift register - another switch, the output of some other circuit, ?

ak

 

Switch is a mechanical device, it will make current go through the cable when its closed, and circuit will be open when its opened. Shift registers clock changes between 2hz (1st 555's output) 50 hz (2nd 555's output) so its only 2 hz and 50 hz it does not get faster and faster. Shift register will not be cleared in any condition, and yes serial input paralel output. Shift register's input is also same with the switch i am talking about, so it is both connected to entrance of shift register, and its connected to mechanism that will switch 2hz clock to 50 hz one.
I dont have blog diagram but i can make it, also my schematic does not matter too much, because if i have the circuit i have mentioned above, i will just implement it to my circuit and life will be easy, so you dont have to know about details of my circuit since it would not interact with my original circuit much, aside from changing its clock.

 

Take a look at this link particularly Fig 3. it looks like it could be helpful to accomplish what you want.

 

You could also set the 555 to the highest frequency and use a binary digital counter to reduce the frequency to the lower value.
Then you just have to logically select which output frequency you want.

 

you dont have to know about details of my circuit

That's it. I'm out.

 

That's it. I'm out.

I mean it is not matter how my circuit works, do you have to learn everything about CRT monitors to design a remote control? Its like that as well, i only want designing of specific par, i can do its implementation to my circuit.

 

Take a look at this link particularly Fig 3. it looks like it could be helpful to accomplish what you want.

I mean i do know how flip flops work but i can only design them with 1 input, i just cant draw state diagram when there are 2 inputs (which are outside of flip flop outputs) so im just like stuck in terms of how can i operate with flip flops in my case.

You could also set the 555 to the highest frequency and use a binary digital counter to reduce the frequency to the lower value.
Then you just have to logically select which output frequency you want.

Well i can do it but the part i am stuck is actually how can i use my B as initial trigger and A as ending trigger. Like if it was only will be triggered when B was only 1 or only 0 that would be easy but, whatever the change is, when change happens on B the circuit must be triggered to switch clocks and when A changes from 0 to 1 or 1 to 0 circuit must be triggered to switch back clocks and after that it should hold its state untill B gets changed again.

 

................
Well i can do it but the part i am stuck is actually how can i use my B as initial trigger and A as ending trigger. Like if it was only will be triggered when B was only 1 or only 0 that would be easy but, whatever the change is, when change happens on B the circuit must be triggered to switch clocks and when A changes from 0 to 1 or 1 to 0 circuit must be triggered to switch back clocks and after that it should hold its state untill B gets changed again.

Sorry but that's not clear at all.
You may be able to use a latch to do the switching but if you can't post a logic table of exactly what signals or signal sequence cause what SR frequency, I can't help you any further.