I really need to keep closer tabs on what x0xb0x is doing on the internet. First it torrented some DiVXs from The Pirate Bay. Then it starting trolling craigslist and buying stuff on Amazon with my credit card. Now I find out x0xb0x even has a myspace page!
I blame m0me rath because hes got 4 of them and they probably needed a place to hang out!
In other news, I’m putting up a track in the x0xb0x ‘podcast’ nearly every other day! Check it out for the latest, soon I hope to have it automatically syndicated here.
People on the ladyada.net forums have all sorts of projects they work on. Mike Witt wanted to measure capacitance but his meter doesn’t have a C measurement mode.
However, he remembered that in 555 timers, the frequency is dependent on capacitance so he whipped up this super-simple capacitance meter. Initially I suggested going with the AC waveform method but this is probably just as good and much easier. Just vary R1 and R2 to get different frequency ranges for measurements
(I forgot to add values, R2 and R1 are both 1k ohm
Q is the output, that’s what I hook to my scope.
C_HI is the high end of the cap (if you want to test a polarized cap)
C_LO is the low end. –these don’t matter on standard ceramic caps
Vcc should be between 5-9v, but can be up to 15v safely. 5v is a good TTL level.
To find out C, use the equation C=t/R (from t=RC)
Since my scope only gives frequency, I substitute t=1/freq
We know R (R=r1+r2), so we get
In my test case, I get freq=2.25676kHz
that means that freq=2256.76Hz
The Cap I used was labeled 224J, which makes it a .22uF +/-10%
I finally got around to rewriting the flickrnotes code i wrote to support IE6/7 as well as overlib. Ironically, as a side effect, I had to do this funky opacity thing because in IE you cant have onMouseOver() on an ‘empty’ DIV or SPAN tag unless it has a background color. However, background colors with opacity work just fine.
One could always just keep the Opacity 0% and mess with outlines but i kinda got to liking this look.
For an upcoming project I need a variable clock source: up to 50MHz and as low as 10KHz. So I looked up VXCOs, PLLs, DDSs, etc etc. all not quite what I wanted.
And then I found this, the LTC6903, 1KHz-68MHz SPI (or I2C) programmable oscillator, 8 pins, <0.5% error, no crystal (?!). Theres also a resistor-controlled family (LT1933 in SOT23-5). This is the coolest thing ever!
Check out this kinky "typical app"
As Javaman says, “its like a monk that can control his own heartrate”