Best way to cheaply measure AC current

[Dejan567]

This is reference to my earlier post: https://www.eevblog.com/forum/projects/weird-coil-configuration-does-it-classify-as-parallel-lc-circuit/

Please refer to this post and specifically Reply #24 for more information about the exact set up. I am looking to measure the current on either the input or output as accurately as possible without buying a super expensive current probe or wasting a lot of power. If having to choose, I would rather do the latter.

The current probe I currently have is MicSig CP503B, which to my understanding can measure only 20 mA reliably. Again, I am working in kHz to low MHz range. Budget is, of course, limited.

I am using a signal generator to drive my circuit. Now I know impedance matching is a significant issue here as well so looking for suggestions or to know if it's even possible  (and how to do it, precisely). I was thinking of using a precise resistor in series and measure the voltage drop across it but again there is the impedance matching issue.

Any suggestions? Please give as much detail as is possible.

[moffy]

This is a reference to an open source wideband current sensor, you probably just need the current transformer and amplifier not the Hall effect part: https://www.sciencedirect.com/science/article/pii/S2468067218300592

[aliarifat794]

The cheapest that I can think of is ACS712. ACS712 is an AC or DC current sensor, which is used to measure AC or DC current. You should also have a look at Difference between AC & DC Power, that will help. The maximum value of AC and DC which can be measured is 30A, its output current signal can be read via analog I/O port of Arduino.
https://www.theengineeringprojects.com/2019/03/introduction-to-acs712.html
Here is how you can measure AC current with ACS712 and Arduino.
https://microcontrollerslab.com/ac-current-measurement-acs712-arduino/