kevin gilmore

10 boards plus 3 transformers plus 5U case per side 1 x hv ground reference 2 x hv900 1 x driver 1 x output

174k will be fine

cascode current sources at 1 amp, not so easy parts are not available

everyone wanted tiny. they got tiny. i could do singles sic diodes or schottky dioes, board has to get a bit bigger. and the noise is already 140+ db down. i can't measure that at home, my led lights over the bench generate 7mv into a single turn of wire. and the switcher in the burglar alarm, and the high frequency switcher in the whole house UPS... and the switcher in the variable frequency drive for the AC... and at work, just barely can i measure. the stuff that does -160 to -170db seems few and far between. And in the stupid price category.

the noise spikes are 120hz (100hz for you) and due completely to the switching noise of the input diodes. every power supply, even tube rectified ones do this. The idea is to remove the spike noise, and its not easy. caps across the diodes, etc, just does not work. and by the way, so far, I can't even get close to these numbers with a shunt regulated supply, the noise rips right thru the main current source. 7815 is rated at 90 microvolts of noise (ti datasheet). which is great except that in the typical configuration the diode noise rips right thru, and is usually in the millivolt range. and the voltage stability is +/-4% over commercial temperature range. plus line and load regulation. S22, same thing, the capacitance multiplier at the input is useless. Some companies in the stupidly overpriced 3 terminal replacement business call this a gyrator. Nope, not a gyrator. yes it can regulate at 3V, but you don't want to do that. What you might want to do is use that voltage to calculate line voltage -15% for the absolute minimum voltage. Then make sure all the components are rated for line voltage +15% its all about heat in the pass transistors. if you want to go down to 8 volts, you have to change the series zener to 4.7v that zener is there to make sure the thing starts up under load. and change the reference to 5v here is the original design that was modified by ucc, then modified by me. http://waltjung.org/PDFs/Improved_PN_Regs.pdf

http://gilmore.chem.northwestern.edu/kgsshvcarbonproductionv5.pdf so for original servo, adjust the amplifier for an output voltage around zero then put the jumper in for servo v1. for the new servo, adjust the amplifier for an output voltage around +20v then put the jumper in for servo v2 never put both jumpers in at the same time.

can't really zero the input dc. some of the that340 are better than others. if you can get the lsk170/lsj79 parts, those sub directly. and have much lower offset currents. on the 8 boards I have done, all adjust to less than 1mv.

exactly, and a few parts removed http://gilmore.chem.northwestern.edu/kgsshvcarbonv5.jpg this guarantees that its gonna work, but its gonna work anyway! reduces the GB price!

Kerry is a bit nervous that the v3 servo for the carbon may not work, so I did a v4 board which has both servo's on it, use one or the other. Much safer for the group buy I think. http://gilmore.chem.northwestern.edu/kgsshvcarbonv4.jpg

those are bipolar inputs, with a bit of offset current, so you really need a 10k input pot, or 10k resistors to ground. other than that I listened to my latest set of boards on the new power supply, and there is definitely a noticeable difference in noise with iem's.

yes, buy a bunch. but it is more money than an open frame ps.

I guess that the next thing I have to master is micro engraving. I do have the tools...

if you do the 2 complementary singles, then yes, otherwise no. also the bom lists the on board pass transistors, not the off board ones I did more testing, and at 500ma, the minimum dropout voltage seems to be closer to 3v. But at 5v, the pass transistors do just fine with a small heatsink as is. 5V, 500ma ... 2.5 watts

not an error. from the krell power supply, 10 ohm resistors from iec input ground to power suppy ground. not likely that anyone including me is going to use it though.

ground down the middle. there is actually a benefit of dual supplies. the noise spikes what little of them exist cancel.

2 watt transformer... no 22 watt, just barely 30 watt transformer is about right one of the mounting holes is 25th off of square. current posted boards (dual and singles) have the mounting holes one size smaller, the silk screen fixed, and 1 resistor each moved by 25th. done measurements this morning in a screen room is about 800picovolts of noise. and voltage stability exceeding 6.5 digit meter. anything better is going to require stupidly expensive test gear.

its a 10 volt reference, the feedback resistors are 1.5k which is a divide by 2. So if you change the top 1.5k resistor you can get any voltage you want. 750 ohms makes it 15v http://gilmore.chem.northwestern.edu/goldenreference.pdf change R8,R9

likely depends on current level, have to bolt to heatsink to test. at 500ma output, looks like about 4V

you can with parts changes including higher voltage rating caps, and opa445's take the output voltage all the way up to +/-60V in which case you need the ratings on those transistors. compared to everything else, the transistors are among the cheapest of the parts.

my unreg primary is 41v, so its way higher than normal. I did attach the biggest U bracket heatsinks I had around (bhse ones) Ran 500ma load. Definitely gets too hot to touch in a few minutes. you do realize this is set for +/-20, so if you want other voltages you have to change the feedback resistors. (+/-20 is my favorite voltage for ssdynalobal)

I'm happy to report that the goldenreference low voltage dual power supply works as designed, and tests less than 1 microvolt of noise. Going to have to take it to work and put it in a screen room to really measure the noise. http://gilmore.chem.northwestern.edu/goldenreferencedual.jpg however there is one silkscreen error seen by the extra + near the 47uf cap on the right side. I will update the files shortly. All 4 of the 47uf caps need to have their plus sides pointing to the left. very happy with this

mine looks a fair bit different, 4 inch long cylindrical thing labeled 5%

unscrew the red barrel on the hv probe and notice the accuracy of the resistor.

this is all about the real impedance of the dmm. Almost all of which are specified as 10M. But when you actually measure them, all over the place. especially if you have over-voltaged the thing a few times. So its a random number generator. The real ultra high impedance meters are expensive, and the high voltage probes are +/-10% it would be nice to get rid of all the zeners in the bias supply with some ultra accurately regulated power supply. it would be much lower noise, but way more complicated. pretty much another hv supply with smaller caps

The test point on the power supply is low impedance! So 580 there is 580 no matter what kind of meter you use. most of the other amps don't have test points, and the only thing you can do is measure at the stax jack which is 4.7M away from a low impedance voltage source. for all of my newer power supplies, the 580v is generated with zener diodes, and is not adjustable like the much older supplies.