lordpil's blog


how was james not names that

Posted by renesis at 17:04 | permalink | 0 comments


so like, you think programmers an hero'd a lot before ^z was a thing?

Posted by renesis at 15:46 | permalink | 0 comments


ya
end of that is perfect

Posted by renesis at 11:09 | permalink | 0 comments


you can just jumper it out, or just use the series resistance, put a tiny cap in there for esd and rf immunity, or setup the cap as a tuned filter
but if you use cap as a filter, you have to take into consideration impedance of the source
not just the 100R or whatever you put there

Posted by renesis at 07:59 | permalink | 0 comments


so like, that right at the input pin, followed by series 100R or ferrite, followed by reverse bias diodes to rails and 100pF cap to ground is good input strategy
tweak to suit BOM or signal integrity needs
depends on load
if youre loading with 10k+ its like, 1% drop in level
maybe noise from diodes, dont use glass ones
i dunno, 1n4148 are used a lot, so you can find faster and higher current solutions if you need to
a lot of designs will have a general purpose diode used in a lot of places for protection or signal current things
if its not mass production, unprotected isnt unusual
RC on inputs is super common

Posted by renesis at 07:54 | permalink | 0 comments


its very difficult to make things 100% immune, but doing things that makes sense always helps
but like, sometimes if you fix things breaking, the energy moves past to other parts, its kind of a wackamole thing
http://www.st.com/content/ccc/resource/technical/document/application_note/f4/7c/88/47/75/08/42/a8/DM00035396.pdf/files/DM00035396.pdf/jcr:content/translations/en.DM00035396.pdf
spark gap section, page 11, has an equation for doing spark gaps

Posted by renesis at 07:49 | permalink | 0 comments


i think tvs diodes are built for pulse currents, also usually bi directional
in ESD testing, what works is dependent on loading and layout
sometime sparkgap to ground fixes everything
sometimes, series ferrites or 100R worked
usually something like 100pF to ground after

Posted by renesis at 07:44 | permalink | 0 comments


iunno
if a noise glitch can cause something bad, probably yes
if you are logging data and want to see the noise, no
then averaging or an RC filter works
tradeoff is latency
reverse biased diodes to ground and supply, and series resistance and parallel capacitance also work
tvs diode are expensive and harder to source
theyre less common that reg diodes in circuits

Posted by renesis at 07:39 | permalink | 0 comments


giant film input coupling more common on studio stuff

Posted by renesis at 05:57 | permalink | 0 comments


usually the dance is like, tweaking for higher resistance so you can use lower value caps, without fucking up noise floor
if its a one off and you want to big hammer solution and you have money, sure get film caps all around
theyre also huge
above 0.1uF gets impractical
like, on home audio you will see bipolar electrolytic coupling, or biased circuits and regular electrolytic
or a film box cap the size of an egg

Posted by renesis at 05:52 | permalink | 0 comments


what is CRR
CMRR?
yeah not the same thing
unless you have the microphonic output on bias circuits going to both inputs
PSRR is how much ripple and noise on the supply gets into the signal
power supply rejection ratio
anyway, film caps are $$$, ive only seen them used in signal path

Posted by renesis at 05:47 | permalink | 0 comments


microphonics?
electrolytics are okay i think, theyre just not very consistent vs freq, and they have shit tolerance for filter circuits
MLCC are way microphonic, small value ceramic disc cap, i dont think its an issue so much
right MLCC are microphonic
but for supply, its probably fine
you can lookup power supply rejection ratio
for opamps, and you can figure out how much gets in if you have bias circuits going to psu

Posted by renesis at 05:42 | permalink | 0 comments


Top | Add to Technorati Favorites


© 2007 lordpil.   XHTML 1.0! CSS! Site design by GNAA  Blog Engine by pbx | MULTI2 | ian hanschen | lolwat