Homebrew PCBs

A couple of 555 timers makes a surprisingly accurate and sensitive capacitance meter. Uses your DMM in 200mV mode. In the lowest setting, 1mV = 1pF. Measures down to 0.1pF resolution, keeping in mind it isn't that accurate, but you can see the capacitance change as you wave your hands around.

http://www.polyphoto.com/tutorials/ElectronicCircuits/

Build it with parts from your junkbox for next to nothing.

Or if you can program microcontrollers, do the same thing in software. Regular clock followed by a monostable, the cap under test is in the monostable. Measure the time it takes to charge the capacitor.

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan <stefan_trethan@...> wrote:
>
> It doesn't seem to take 4mm test leads.
> I have some meters with that kind of slot thingy, and never use them.
> It's just so much more practical for me to use normal test leads.
> 
> This is also useful:
> <http://www.measuretronix.com/files/u2/Fluke-TL2x4-TWZ.jpg>
> 
> You can also use half of a set of kelvin leads, like these:
> <http://www.amptec.com/images/720pencil.jpg>
> I use them often when I can't find the first type in my mess.
> 
> 
> Both types of probes can now be bought very cheap direct from china,
> no need to spend big $.
> 
> If you need to measure a lot of caps there are test fixtures, probably
> a bit expensive to buy but should be fairly easy to make yourself:
> <http://www.datatec.de/shop/pix/a/n/1155936930-22235.jpg>
> 
> 
> ST
> 
> On Sun, Mar 7, 2010 at 4:35 PM, sailingto <sailingtoo@...> wrote:
> > That is a nice looking meter with good specs.  I guess it has a function to zero out the leads affect?  And really not that much more than what I have - the one I have is $136 shipped here in USA.  Kit is $30 less.
> >
> > If it came with tweezers for SMD stuff would really  make it nice.  I like the ohms function - is it really accurate?  Have you checked any .1% resistors?
> >
> > Ken H>
> >
> >> I've got one these.
> >>
> >> http://cgi.ebay.com.au/TH2821-LCR-Meter-inductance-capacitance-and-R-1Khz_W0QQitemZ280467653417QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item414d2cc329
> >>
> >> Its about another $50 more than than the L/C meter above, but its specs
> >> are better. 4 port measurement at 100Hz,120Hz,1kHz or 10kHz with L, C &
> >> R resolutions of 10nH, 100uOhm and 10fF respectively. It's only
> >> disadvantages is the poorly thought out user interface.
> >>
> >
> >
> >
> >
> > ------------------------------------
> >
> > Be sure to visit the group home and check for new Links, Files, and Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> >
> >
> >
> >
>