# frequency conversion

Discussion in 'General Electronics Discussion' started by clw143, Jul 24, 2012.

1. ### clw143

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Jul 24, 2012
I have a 12V pulse frequency

I would like to build a frequency converter based on a user selectable ratio via two (2) dipswitches or selector switches.

The two selector switches would give your out put ratio based on those positions selected, (switch position 1) : (switch position 2) 1:1, 8:1, 3:7, 1:4, ect.

Basically a multiplier or divider for pulses per second. (2:1 would be half the frequency, 1:4 would be 4 times the frequency, ect.)

Thanks in advance for any help.

Last edited: Jul 24, 2012
2. ### Harald KappModeratorModerator

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Nov 17, 2011
You can use a PLL (e.g. 4046) to generate the multiples according to the setting of switch 1 (see 4064 application notes).
You can use any presettable divider (e.g. 4018) to divide according to the setting of switch 2.
I suggest that you set up the circuit in the order
1st multiply
2nd divide
Thus any jitter introduced by the PLL will be reduced by the following divider.
Note that the output for some ratios will not have a symmetrical duty cycle, for some ratios it will be symmetrical.

These ICs can be operated directly from 12 V. If you use 74xx type ICs, the operating voltage is limited to 5 V or less. You will have to donwscale the input clock (simple resistive divider) and possible will have to upscale (simple transistor amplifier) the output signal to 12 V.

Harald

3. ### GreenGiant

842
6
Feb 9, 2012
2 options that immediately come to mind are using a 555 with a variable resistor (this would not be able to give you set frequencies like that, it would ramp up and down)

the other is get a solid state relay, and a microcontroller and program it for a multiposition switch/dial but you would need a steady 12V supply to go through the relay otherwise you would only be able to go up to the frequency of the supply

4. ### CDRIVEHauling 10' pipe on a Trek Shift3

4,960
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May 8, 2012
You made no mention of frequencies and pulse width. We don't know if you're talking Hz KHz, GHz?

Why not? A dip switch and fixed resistors can easily replace a Pot in a 555 RC time base.

5. ### clw143

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Jul 24, 2012
I suppose I would like to use it for testing purposes and it to just give an output of what ever the input range is, but the useage in mind is currently in Hz.

6. ### davennModerator

13,866
1,958
Sep 5, 2009
testing what ? audio circuits ? radio circuits, digital circuits ?

please give more background on what you are trying to achieve, then members on the forum may be able to offer you specific help
At the moment we are all just guessing as to what you are wanting to do

cheers
Dave

7. ### GreenGiant

842
6
Feb 9, 2012
Didn't even think of that, that would be a valid option.

Basically use your dipswitch but have it redirect a signal to a few pins on a microcontroller
then set it up so if its on this pin pulse the solid state relay at this frequency, if its on this pin use a different frequency

BUT if you do that you need a solid 12VDC rather than an existing waveform (square wave I'm assuming) if you have an input frequency of 500Hz it would be difficult to output 5000Hz (he said that he wants multiples of the input as well as factors of the input)

8. ### CocaCola

3,635
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Apr 7, 2012
FYI: When doing this it's best to use full binary logic and monitor all the pins connected to the dip, high and low state... This way a 2 position DIP can be used for 4 options vs 2, and a 4 position dip can be used for 16 options vs 4, and so on... Saves a lot of I/O pins...

9. ### GreenGiant

842
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Feb 9, 2012
You could do that too, though it seemed like he/she didnt need that many positions