kevin gilmore

I still have a bottle of some Cuban liquor that my parents brought back from their honeymoon 63 years ago. Still tastes great. If scotch (or any other whiskey) only lasts 6 months, I'm going to have to take the next 2 months off of work and go on a real bender.

board getting there http://gilmore.chem.northwestern.edu/tubehybrid.jpg

the 15 second startup delay is intentional. you can change the resistor string to make it more or less sensitive

test circuit certainly worked, and I don't believe in virtual grounds for all sorts of reasons. when you are running a dynahi with 400ma of bias, 25ma to turn on the relay seems tiny

It appears that the LM339s are powered by V+/V- rather than V+/GND? yes The LM339 has 4 comparators in it. It appears that 2 are being paralleled for each input signal? yes, one for the + limit, the other for the - limit and then repeated 4 times for each of the signals The input protection diodes run from V+/V-? to the inputs of the lm339, not as shown. this should make it easier http://gilmore.chem.northwestern.edu/protector3.jpg

yep. if you match the fets with the transistor tester you can get that 2.2V down to about 100mv but you need a bunch of them, over a 4:1 range on idss done

lots of variation in the fets. i had to hand pick, and throw out a few. the 1.45 volt is not that out of range, i can actually get mine to 160ma. you measuring the 2V without the servo? the servo takes about 30 seconds to bring it to about .1v or less.

this circuit is ground referenced, so not suitable for megatron style stuff. Unfortunately, the only thing that works there is the T2 circuit, or something like it due to having to drive the output tube at -500V was not aware of the other Fairchild parts, definitely in this case better than the higher voltage parts. Really only need 200V parts

so this has been kicking around for a while, decided to publish. take my ubaltobal converter, cut it in half, and then take the top piece, replace the input transistor with a tube... high impedance input... DC coupled, no negative feedback, less than .01% thd, 10db gain... just add a high power bipolar output buffer, and cheap tube hybrid with lots of plankton. work in progress http://gilmore.chem.northwestern.edu/tubehybrid.pdf 100 volt power supply real simple with TI TL783 high voltage regulator +/-30 supplies with lm317/lm337 with boosters cheap!

100ma AC it sure would be nice if transformer manufacturers would understand that what i want is a specific DC current, given a diode bridge and a capacitor and then calculate what the peak AC current is, then build the transformer that way. But none of the manufacturers seem to have the slightest clue.

slightly updated board file

They float on the board too. not tied to the outputs. For power supply caps i like to do complete solder to ground as the thermals have some impedance, especially at higher currents.

you want the pps washers http://www.aavid.com/product-group/accessories/washers they go most of the way into the ceramic insulator and prevent arc's thru the center of the insulator pretty sure I use the 7721-300sg will look later

For filament lines, best to have 2 or 3 oz copper, so either you make the trace a bunch wider, or you get thicker copper. Amperes of filament current... the high voltage eventually jumps around the insulator, so best to use the ceramic insulator with the special feedthru that goes along with it. then and only then can you use the metal screws.

just posted cfp2 to the boards directory I have not had boards made yet, or tested, prototype works fine. someone needs to check the board.

andy built a diy-T2 as his first audio project...

18ma @ 20 volts power supply is 360mw. about 1/3 of full power, and they definitely get hot. But you can crank it if you want.

looking very nice reminds me of something but i can't remember what it is

i have a whole bunch of greenlee punches from .5 inch thru 3 inches The only way to go for chassis up to 3/16 inch thick i even bought a square one for doing the iec sockets. birgir can supply pictures of what happens when you try to use them on 10mm panels

if I have time I plan on looking into the screws issue on Monday.

the ksa1156 is a 400 volt device. The 270V zener across it prevents it from blowing up on turn on. You can leave the zener there for the 600v part

from pictures that have been posted elsewhere including bottom and top of the board, there is no protection on those caps. The manufacturer specifically states that if you put more than 2 in series (and Vinnie is putting 9 in series) you absolutely have to have 3V protection on each and every cap. Because somewhere past 3.1V the cap explodes. $500 in caps for absolutely nothing.

as always the devil is in the details, so lets look at this 24V cheapass switcher power supply brick supplies power to the caps. And probably fills the chassis with high frequency hash. 2 banks of caps, one charges, the other supplies power to the unit. Now is this +/-12V, or is this +24V single with the amplifiers capacitively coupled outputs. In either case, headphone output power is pretty limited. How far in voltage does the cap sink before it switches. So the amplifier and the rest of the stuff continuously see's the equivalent of triangle waves on top of the power supply. How often does it switch banks. How well isolated is that switching, and is it audible. What about the fact that all of this is to get rid of power supply noise, and ultracapacitors are electrochemical, and have way more noise than either lead-acid batteries, or well designed power supplies. A solution looking for a problem that can be made to not exist in far cheaper ways. but it does seem to be fairly well built.

The electrolytics may be one thing, but taking out the .01 caps that are absolutely as close to the circuit as possible, and hanging something on the end of at least 6 inches of wire is going to cause all sorts of problems. Don't even care if the caps are super trendy or not. plus the fact that the solder job is likely poor.

just wait till you turn 40