question about 4046

[schmelfhelp]

Hi

just a quick background before my question. I have built bits and pieces from schematics over the past few years but I'm only just starting to understand more about how it all works. I have a fine arts background and I'm probably using all the wrong terms so I hope this makes sense.

I am working with soft circuits and building my own pots. So far the pots I have made jump around a bit. One thing I would like to do is scale the range (and smooth) them.

I was playing around with a 4046 and I'm wondering if I send the output from the pot to the input on the 4046 could i use the min fc and max fc to scale the output to a range that is more useable? (eg if my pot is 20 - 200k can I make it output 0 - 10k)

I get the feeling that maybe the output of the pot and the input on the 4046 are different types of things altogether, but just thought I would ask.

Does anyone have any suggestions on how to change the range (or scale) a pot? Or how to smooth the output. It would be good if I can control the range as the pots i make change a bit with weather and age. I know i can do it using an arduino but I would rather not use an arduino for now.

thanks for your help!

[andrewF]

hi
yep it is quite difficult to understand what you are trying to do -
no worries, we were all newbies once

Usually when we consider the output of a pot we talk about a voltage rather than frequency. There are a number of ways to scale the voltage using resistors.
I assume this voltage is then used to control the frequency of an oscillator.

Probably it would help if you can post some schematics or diagrams of what you are doing.

[JingleJoe]

I think you're geting voltages and resistances mixed up. Look up ohms law and it will all become clear.

If you want to change the range of a pot add a resistor in parallel then use the parallel resistor equation to find the value:

Rt = (R1 x R2) / (R1 + R2)

And what do you mean by jumping about? If the resistive trace is dirty or uneven this will cause the wiper to disconect and the circuit will basically go open circuit. To remedy this, clean your trace and make sure the pot wiper movement is smooth.

[schmelfhelp]

Hi Thanks for your replies. And sorry to be so slow to get back. real life took over and I have been offline for ages. I think that I am definitely confusing things here. For the moment I'll do some reading and ask some simpler questions.

Thanks for the responses.

[Uncle Krunkus]

Generally,
to "smooth" the output of any pot, either passively, or with op-amps, you're gonna be looking at a capacitor to ground. Depending on the open circuit resistance, a passive capacitor will "hold" the voltage for a short time, thus smoothing out the function of the pot. This is assuming the pot is used as a voltage divider. In other situations, effects would vary, depending on the circuit.
Otherwise, you're looking at an op-amp setup as a glide generator. You'll find examples of this all over the forum, especially in the glide circuits of the Klee Sequencer.

[schmelfhelp]

Awesome! thanks heaps!
You somehow understood what I was trying to ask.

[Uncle Krunkus]