tag:blogger.com,1999:blog-873449337697168887.post831160220564000303..comments2023-04-14T10:54:01.240+01:00Comments on Hmm... There's An Idea: Capacitance Measurer v1.0Unknownnoreply@blogger.comBlogger11125tag:blogger.com,1999:blog-873449337697168887.post-20026096896295423072010-03-09T17:28:41.134+00:002010-03-09T17:28:41.134+00:00I could be completely of the mark here (I blame it...I could be completely of the mark here (I blame it on too much coffee and too little sleep), but do I understand correctly that you are essentially measuring the first time constant up to 63.2%? <br /><br />How about taking a second measurement for the second 63.2% charge and then comparing results? <br /><br />I would display both those values as well as an average. If all 3 are close together, the reading is probably accurate. If not, it could be a faulty cap or it could be stray capacitance, etc... <br /><br />Does this make sense?Riaanhttp://www.riaancornelius.comnoreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-48273826192050485962008-07-05T15:34:00.000+01:002008-07-05T15:34:00.000+01:00Very true Makoto, That would have been taken into ...Very true Makoto, <BR/>That would have been taken into consideration if the calculations were done with the true values of the voltage, not just the 10 bit value from the ADC on the arduino. Since everything will stay (roughly) proportional, it didn't matter to me, especially considering the fact it was just a proof of concept for myself. When I remake the circuit, i'll try to make it as accurate as possible. <BR/><BR/>Thanks for the comment,<BR/><BR/>Chrisadminhttps://www.blogger.com/profile/07087766696095795011noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-41613345426308571062008-07-03T16:26:00.000+01:002008-07-03T16:26:00.000+01:00With the diodes in place, it'll drop the output vo...With the diodes in place, it'll drop the output voltage of the arduino by 0.6 volts (assuming they're silicon diodes). Won't that affect the way you're calculating the capacitance?Makotohttps://www.blogger.com/profile/16384018337009640668noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-77673980252664484722008-06-30T20:07:00.000+01:002008-06-30T20:07:00.000+01:00Well I'll definitley let you know mhen mine is up ...Well I'll definitley let you know mhen mine is up and running, though it might be a couple of weeks (Im finishing up a couple projects atm)<BR/><BR/>And btw I meant send you the actual capacitors, not just the results.Kamonhttps://www.blogger.com/profile/15274084893078554744noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-59559950979530772562008-06-30T18:47:00.000+01:002008-06-30T18:47:00.000+01:00Thanks very much for the offer, but, without the a...Thanks very much for the offer, but, without the actual capacitors, I cannot really do anything. <BR/><BR/>What really needs to be done is you getting yours set up, in it's final configuration (i.e. on perf-board or something - not the breadboard), get the value from the scope, then get the value from the Arduino and plot the graph.<BR/><BR/>When capacitors are measured in different circuits, the integer value from the Arduino will differ; especially with the lower end - stray capacitance and whatnot all over the place!<BR/><BR/>Let me know how you get on when you get round to it, I'll be interested to hear. <BR/><BR/>Thanks again,<BR/><BR/>Chrisadminhttps://www.blogger.com/profile/07087766696095795011noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-40668931559288601572008-06-29T22:42:00.000+01:002008-06-29T22:42:00.000+01:00I wight be able to access one. Perhaps I could mea...I wight be able to access one. Perhaps I could measure a few and send them to you (of course I'm looking to build one of these too. It would be super awesome for home brew capacitors.)Kamonhttps://www.blogger.com/profile/15274084893078554744noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-71179376209665293352008-06-29T22:14:00.000+01:002008-06-29T22:14:00.000+01:00I wish! I plan on trying to make one soon, proboab...I wish! <BR/><BR/>I plan on trying to make one soon, proboably with a USB compatible PIC, with my monitor as the scope's screen. <BR/><BR/>Normal RS232 serial communication wont be able to transmit fast enough to detect a high(ish) input frequency - about 11KHz max. with 115200 baud, 10 bit ADC and no start/stop/parity bits. <BR/><BR/>Hence the USB - minimal speed is about 1.2Mbps which is already 10 times faster, bringing it up to about 100KHz. If I can get 48Mbps working properly, that'll give me about 4MHz with no start/stop/parity bits. I'll just have to make sure the ADC doesn't take too long to settle and that the PIC can take a fast enough crystal. <BR/><BR/>It'll be a challenge.adminhttps://www.blogger.com/profile/07087766696095795011noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-4868163021632068682008-06-29T21:18:00.000+01:002008-06-29T21:18:00.000+01:00Do you have access to a oscilloscope? You can mea...Do you have access to a oscilloscope? You can measure them using that with the right knowledge (basically tho same method your using)Kamonhttps://www.blogger.com/profile/15274084893078554744noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-45890757068895137862008-06-25T18:33:00.000+01:002008-06-25T18:33:00.000+01:00Thanks for the input guys. I did think about the a...Thanks for the input guys. <BR/><BR/>I did think about the actual values for the capacitor compared to the stated. I wasn't sure what to do to try and get rid of that possible error, besides buying a real capacitance meter, I couldn't think of anything. Any Ideas? Buying a real capacitance meter would be completely against the idea behind building the circuit in the first place!<BR/><BR/>Thanks anonymous, whoever you are. That article may end up being quite useful.adminhttps://www.blogger.com/profile/07087766696095795011noreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-4445880143003201502008-06-25T13:17:00.000+01:002008-06-25T13:17:00.000+01:00This article goes into the interrupt side of thing...This article goes into the interrupt side of things and might be useful<BR/><BR/>http://www.uchobby.com/index.php/2007/11/24/arduino-interrupts/Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-873449337697168887.post-48988431572811412912008-06-25T11:48:00.000+01:002008-06-25T11:48:00.000+01:00This is a great project both for fault finding and...This is a great project both for fault finding and for parts salvage. <BR/><BR/>In both cases the printed value of the cap can't be trusted, it needs to be compared with actual behaviour.<BR/><BR/>Thanks for sharing this.Anonymoushttps://www.blogger.com/profile/14968713136858614922noreply@blogger.com