Increase clock frequency

Thread Starter

Matteo3033

Joined Dec 18, 2020
8
Hi, I’m working on a logisim project for university.
I need to increase the clock frequency to 16 Hz, but the frequency must be set in the options to 1 Hz. How can I increase the frequency using only a circuit?
Thanks for the help.
 

Papabravo

Joined Feb 24, 2006
14,868
Hi, I’m working on a logisim project for university.
I need to increase the clock frequency to 16 Hz, but the frequency must be set in the options to 1 Hz. How can I increase the frequency using only a circuit?
Thanks for the help.
Build a VCO and a phase locked loop. Divide the VCO output down and phase lock it to the 1Hz. clock.
 

ronsimpson

Joined Oct 7, 2019
1,125
I have one working in a different program. I have Logisim but can not get it to work. Post your circuit and others can also play with it.
There is a famous circuit using a XOR and a RC delay that doubles the frequency. We can not use a RC but we can use a delay. The manual said you can set the delay of a gate. I do not know how in Logisim.
1608342138030.png
Here I started out with a 1hz square wave. A2 is a buffer but a inverter will also work. I set the delay to 0.25 seconds. The output is 2hz.
My circuit, that I did not post all of, is out putting 16hz. (home work) Please see what you can do in Logisim and see if you can make it work.
 

Papabravo

Joined Feb 24, 2006
14,868
Sorry, but I’m new to logisim... what are a VCO and a phase locked loop?
VCO = Voltage Controlled Oscillator
A phase locked loop is partially analog/partially digital circuit that compares the phases of two input signals and produces a control voltage proportional to the phase difference. A simple phase detector can be made from an Exclusive OR gate. That of course is no the only way. The control voltage will often have a compensation loop to counter abrupt chance to the input to the VCO. Probably not a practical suggestion for your experience level in electronics. Sorry, I wasn't aware of any Logisim limitations since I am not familiar with that particular program.
 

Thread Starter

Matteo3033

Joined Dec 18, 2020
8
"must be set to 1hz" "Must" who said must? Is this a school project?
It's a project for university: the professor told me to set the clock to 1 Hz.
Here I started out with a 1hz square wave. A2 is a buffer but a inverter will also work. I set the delay to 0.25 seconds. The output is 2hz.
My circuit, that I did not post all of, is out putting 16hz. (home work) Please see what you can do in Logisim and see if you can make it work.
This circuit makes the clock faster, but, because i can't set the delay correctly in logisim, it doesn't double the frequency. To reach 16 Hz I should repeat this circuits many times. That's not the best solution, but it works.
Thank you.
 
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