# Multiply square wave frequency by 2.45

#### Jeff4033

Joined Oct 16, 2022
1
Hello, I am trying to multiply a square waveform by 2.45. Input frequency will fluctuate from 0Hz to ~1,200Hz. So, I would except an output of 0Hz to 2,940Hz. Does anyone know of something that can do this? I was hoping for a single chip but all I could think of is a PLL which I've never used before. Another idea was to maybe use a Frequency to Voltage then amplify the voltage and then send it to a Voltage to Frequency converter, but these tend to use one shot pulses and not even high and low durations. Sorry for any bad terminology I'm using as I am new at this. Thanks!

#### WBahn

Joined Mar 31, 2012
27,880
It might be easier to throw a cheap little MCU at it. Measure the period of the reference waveform, divide that by 2.45, and use that for the period of your output waveform. You can balance responsiveness (latency) with smoothness by averaging the period over a number of cycles, perhaps using a moving average, to create a low-pass filter.

Also, I think you might have a hard time finding a PLL that will operate at that low a frequency. Depending on how accurate you need the scaling factor to be, a F2V-AMP-V2F is likely to not give good enough results. I'm assuming there's a reason that you want 2.45x and not simply 2.5x.

#### DickCappels

Joined Aug 21, 2008
9,512
How accurate do you need it to be?

Have you considered generating both signals by diving a much higher frequency signal?

#### Ian0

Joined Aug 7, 2020
6,705
Use a 4046 to multiply the frequency by 49.
Then divide the output frequency by 20, using a 4017 followed by a 4013.
I doubt it will be easy.

#### MrChips

Joined Oct 2, 2009
27,679
This appears to be a rather strange requirement.
Perhaps you should give us the big picture of what you are attempting to do.