INSANELY low capacitance !!! Measuring Femto Farads with the LC Meter
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- Опубликовано: 26 сен 2021
- LC Meter v1.0 - coreWeaver / ioCONNECTED
part - 5
In this follow up of the series I'm making a 0.2pF capacitor out of 5 x 1pF 0805 SMD capacitors. The goal was to see how low can you measure in terms of capacitance with this LC Meter.
For the presumed 0.214pF, the measured capacitance was 0.26pF, that's 260 Femto Farads. The measuring error on this domain is estimated to be less or equal with 0.046 pF (46 femto Farads) or somehwere between 17% and 18%.
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This is an open source project. You may use, modify and distribute both software and hardware as long as you give credit.
All the project's files are available here: github.com/coreWeaver/LC-Meter
and here: hackaday.io/project/178081-bu...
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Special Thanks to Neil Hecht for sharing his project and ideas with us. 
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I guess those nice measuring probes and cables you use are making a huge difference especially when you measure small caps and you wanna minimize the errors. I'll try buy the same ones for my LC Meter. Thanks for doing this follow up vid 👍👍
Sir, your just built a piece of art!
The old reliable Tektronix 130 reaches a resolution of 0.5pF with a 5% accuracy along the entire range.
My guess is your LC meter inspired by Mr. Hecht reaches better figures than 5%
I agree with this
great job . love your projects . especially juno
I am using the google translator, so I apologize for any error, First of all, congratulate you for such a good project, I have the first version, check it out and it is similar, only that they use a PIC, but I like this version of yours better, I see it as more refined and Very good finish with enough precision, Of course it can be improved in Your hands, I am already subscribed to your channel from this moment waiting for a much better one, It will be a real pleasure to do it I, I would like, Since you work so excellent, to confuse it to do a Capacities and ESR Meter in a Single Equipment and that in turn gave the losses in the capacitor to be Measured. From already thank you very much for your time. I remain cordially yours. Luis .
I started working on 2.0 right after finishing the first version. I didn't have the time to finish it. Thanks for subscribing !
Well done, great job, keep going
Thank you! 😃
Quite nice , to be able to measure such low capacitance with a homemade device .
it would be nice to be able to measure such low capacitance with any device
Great. Thanks.
thank you !
awesome
thanks man
I have finished the hardware and have done a simple "Hello World". I am having a difficult time loading the Hex File firmware into the Processor. What did you used to load the firmware. Thanks
an ISP programmer and any sw which supports your hardware. you can make your own programmer or buy one. As for the software you can use avr dude, avr studio, bascom. Please be aware: there's no ISP header on the LC Meter PCB. you'll have to flash the fw using another board or an adapter which is trivial to build. google avr ISP protocol or check the m328p's datasheet. thanks for watching !
Thanks for your sharing. Can it measure 30mH even up to 1000mH Coil (inductance )? Since we need to measure such big coil daily. Thanks
Sir, Thanks for sharing this amazing project, I am in a process to build one but i have problem opening the eagle cad files in kikad though kikad supports eagle cad brd and sch files so could you please help in sorting out this error or do i need to open the files in eagle cad only?
I don't have neither have used kikad so I don't know if it's an import / plugin related problem. Why do you wanna open the brd file anyway ? you have all the gerber files in the archive
measuring femto of something is really hard to achieve. You've built a professional lab device or maybe something even better than that
To measure such small values of capacitors, the calibration MUST be done with the probes connected, and the leads dressed as they will be when taking the measurements! (also keep your hands clear of the probes while calibrating! This way the capacitance of the probe wires will be included when the calibration is done, and therefore the lead capacitance will be zeroed out. After the probe leads are attached to the capacitor being measured you must REMOVE your hands so that you won't be adding hand capacitance to the readings.
Finally, what is the smallest values of inductance that can be measured? What about the largest values of L and C?
Also there should be a way to calibrate the meter (actually ZERO the meter) for inductance. To do this, the probes would be shorted and a reading taken of the "zero" frequency for inductance. This way small inductors could be measured, and not include the inductance of the leads.
Also relay 1 can be eliminated by using a DPDT switch to change between L and C. The ground pole of the switch will either ground the inductor or a port pin on the micro controller to let it know what mode it's in. To enter calibration mode would use a push button switch. Now separate calibration / zero routines can be done for L and C. This will allow for the L zero function mentioned above.
The above ideas came from a meter by VK3BHR that used a PIC16F628 (which also has an LM311 equal inside it). I built his meter and it works well, but is limited to measuring C down to about 1pf, and L down to about .1 uh (it reads down to .01 pf and uh, but with +/- 0.01 resolution display it can't be considered accurate that low). The original AEE meter was able to read a lot lower and higher in C and L.