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Everything posted by kevin gilmore
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The soekris board is a perfect example of fucked up. Lvc595 chips where the 0 and 1 can be 60 mv different between drivers on the same chip let alone matching to the next chip. Then the crap 4v references. So when you test for missing codes and equivalent of stuck bits, major issues. Then the drift with temperature. Super expensive stuff (MSB) that use data general series cmos switches not much better. Hand picked discrete fets with hand picked clamps are superior. And discrete. And you will be stuffing parts forever. no tubes. The reason should be obvious
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goldenreference low voltage power supply
kevin gilmore replied to kevin gilmore's topic in Do It Yourself
never tested fully. but probably base drive current may not be enough for 2+ amps -
goldenreference low voltage power supply
kevin gilmore replied to kevin gilmore's topic in Do It Yourself
goldenreference is only good for about 1.5 amps when you need a lot more than that, you have to add an extra set of pass transistors. like the ones on the uber2amp board. And they have to be mounted to a large heatsink -
Group Buy - Digital Attenuator (Kevin Gilmore)
kevin gilmore replied to sorenb's topic in Do It Yourself
latest code from Kerry works with current Arduino compiler, but still does not have the code for the flipped relays http://gilmore.chem.northwestern.edu/volumecontroller.zip -
hinges with torsion springs just like the old thorens dust covers.
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you need the specialized high voltage transistor tester. which do not seem to be on ebay at the moment.
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a1968 has the cutouts between the pins, so could be real. no cutouts, definitely fakes. although the ones from dalbani had the cutouts and were definitely fakes. still a good idea to use a tester first.
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Hook the 2 primaries in series, and test the output. If it's wired correctly you get voltage, if you get virtually zero, they are wired out of phase. It won't hurt the transformer. Don't do this for parallel windings
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in the power supply they are running at only 400v and much less current.
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buy the voltage tester from ebay and test them. Over 1000 volts, they are real, 230 volts and they are a massive pile of fakes from dalbani.
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Group Buy - Digital Attenuator (Kevin Gilmore)
kevin gilmore replied to sorenb's topic in Do It Yourself
Parts sourcing is always fun. This has happened to me several times -
bugs bunny: Oops i had the silly thing in reverse
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reminds me of mikhail hand picking el34 that would work with 400v on the cathode. And the people involved remember how that turned out. kt66 has to go boom eventually and take the j79 and k216 with it.
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and now for something completely different part 3
kevin gilmore replied to kevin gilmore's topic in Do It Yourself
the golden reference power supply setup for +/-40V -
[beavis & butthead mode on] quote "maybe I need to discharge myself" tee hee I've had a very bad day, could not resist. where is steve when you need him.
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I would make sure the comparitors are working as expected. .1hz sine wave makes it easy
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great way to do this, however some heatshrink over the green things to avoid touching the terminals which are at -500v
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not sure where to put this, this is Kerry's first take on a new bh power supply http://gilmore.chem.northwestern.edu/boards/bh-ps-singlerail-v4.zip
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Group Buy - Digital Attenuator (Kevin Gilmore)
kevin gilmore replied to sorenb's topic in Do It Yourself
here is Kerry's code http://gilmore.chem.northwestern.edu/oled_mhz15.zip this supports the original relay board, and the prototype new board, still some software change for the 4 reversed relays for the production board -
and now for something completely different part 3
kevin gilmore replied to kevin gilmore's topic in Do It Yourself
About 400ma DC, peaks up to 600+ma depending on headphones -
stax mafia circuit boards see updated links on page 5
kevin gilmore replied to kevin gilmore's topic in Do It Yourself
It won't. Name should resolve to the right place. this is all about massive amounts of hacking including spoofing, mainly from sites in mainland China. they never get into any of my machines, but they try so hard they are using up to 25% of our bandwidth doing nothing. -
stax mafia circuit boards see updated links on page 5
kevin gilmore replied to kevin gilmore's topic in Do It Yourself
at some point in the next couple of weeks, my server will be put behind a massive firewall. At which point the ip address will change and the dns will change. So it may appear to be down for up to a day. -
there is no 500v version of the carbon, current sources limited to 900v
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my bad on the mislabeling. Hey... people are supposed to check this stuff. updated board file in a minute.
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soren noticed that the 2 inside heatsinks were not grounded. I don't think it makes any difference, but updated the board file to ground those heatsinks