## How to Graph Potentiometer k variable vs Output Voltage in CircuitLab

 Hi All, I'm a newbie to CircuitLab and to Electronics. I am in the process of building a 0~30 V AC power supply which includes a potentiometer to vary the AC supply: - The input voltage to the potentiometer is 24 volts AC from a transformer. - The potentiometer has 3 Ohm to 24.6K Ohm internal resistance. Is it possible to graph the value of parameter K of the transformer vs the output voltage using CircuitLab? In the circuit that I have supplied, I know I can use the Time Domain/Sweep Parameter to graph R1.K against V(PotOut) for K from 0 to 1 in steps of say 0.2, but that does not give me what I want. I hope someone can help me with this. by AlfredC June 14, 2018 Try looking up variac. by mikerogerswsm June 14, 2018 Hi Mike, Thanks for your reply. Using the term "variac", I searched both the CircuitLab Textbook and the CircuitLab Forum but did not find anything that explains how to use CircuitLab to create a graph of (Potentiometer) k vs output. I'm really only interested in learning what I can do with CircuitLab: i.e. can I create custom graphs? Thanks Again, Alfred by AlfredC June 14, 2018 Sorry, my approach to circuit design is a little different. In my day one used maths for the really simple problems and saved circuit simulation to understand more advanced effects. The reason I mentioned a variac is because it presents the best approach to the ac source problem you suggest. Good luck in your efforts, mike. by mikerogerswsm June 14, 2018 Hi Mike, Thanks for taking the time to reply. Just to put this all into context: I'm using the construction of a 0~30 V AC power supply as an aid to learning about electronics. So far in this process I've built my first: full wave bridge rectifier and a voltage divider (to power a dc voltmeter to display the AC output). My next step will be learning how to design and build an Op Amp to supply the output from the potentiometer to the digital voltmeter. So there will be some maths there coupled with the circuit simulation.Thanks again, Alfred by AlfredC June 15, 2018 You will indeed have an ac output, but if you wish to have ac variable power, then I would recommend using a variac. by mikerogerswsm June 15, 2018 Once again, thanks! This is a good learning curve for me, thanks to your input. I've done a bit of reading about variacs. I now realize I've been calling my little project a "0~30 V AC Power Supply" which it is NOT, when in fact its simply a "0~30 V AC Output" as you have correctly pointed out. I did not know the difference until now. This little project, while not being any use as a power supply, has been great for testing my diode, capacitor, resistor circuits in the rectifiers and filters I have built to prove the theories I have learnt. Thanks again. by AlfredC June 16, 2018 Ah, glad that's sorted. I think you could call your project an ac signal source, or if it's variable frequency, a signal generator. See: http://mike-wsm.org.uk/g3.html by mikerogerswsm June 16, 2018 Hi Mike, I've renamed my project"0~30 VAC Signal Source". Thanks for the link to your website; it's full of great projects. I was particularly interested in your power supply: very interesting. I will use your projects as a reference when working on my own stuff from now on. I have started 2 free online electronics courses, one on Analog and one on Digital Electronics from the NESO Academy in India. The lectures are brilliant: https://www.youtube.com/watch?v=yu8xvHHTij0&list=PLBlnK6fEyqRiw-GZRqfnlVIBz9dxrqHJS&index=4 and https://www.youtube.com/watch?v=M0mx8S05v60&list=PLBlnK6fEyqRjMH3mWf6kwqiTbT798eAOm&index=1 I'm sure you don't need this info, but I included it in case some else reading this may benefit from it. Thanks again for you time and information. by AlfredC June 17, 2018

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