kevin gilmore

Would like to see how you take an n-channel enhancement mode mosfet and turn it into a high side current source.

If there was a replacement for the 10m90s i would be using it. It is a very sturdy part, i've yet to be able to blow one up. And I have tried. People in europe should get together and have someone in the usa buy 100 or more of them. Pretty sure there is significant stock in iceland

4 jaw thumb vise. precision swiss made thing designed for watches. The finger thing is on a ball bearing. Not sure where you would buy such a thing these days. I've used it on #80 drills before. Very easy to drill right thru your fingers without even noticing it.

All the boards including yours were reamed with a #74 drill bit. The 3381's fit, but are very tight. I would not go any bigger unless you want to solder both the top and the bottom. U2 plate voltage about 210 volts. My umbilicals were about 3 feet. You should be able to go to 4 feet the only issue is with the filament voltage on the output tubes due to increased resistance.

No need to have a matched quad. More important to have the halves of the input tubes matched section to section.

Well dimming those flood bulbs results in the typical shift in color temp. Tried 75 watt halogens, don't really like them. I have some 50 watt ones i have not tried yet. Tried 15 watt cfl bulbs, ok but... color temperature shifts and warmup which really annoys me. LED bulbs it is. Probably i will spend about $160 on the bulbs plus i have suitable dimmers laying around. 2 dimmers, front and back just like the switches at the bottom of the thing. At least no shift in color temp. And no gobs of heat suitable for melting stuff either. I really like the antique radio. Do realize that the entire chassis is electrially hot, and all the filaments are in series on the 110 vac line. Which is why among other reasons the entire case and knobs are plastic. I did also want to point out that my mantra that "if some is good, more MUST be better" is not always true. Case in point, my corvette is 1300 lbs lighter than my previous jaguar S type R. So 25% less car gives me 25% more mileage and 50% more fun. Similarly too much light for a modern digital slr is also a bad thing. Most of the lenses have their sharpest focus and minimum aberations at two stops down from fully open. So if you have to put stop the lens down to f32 you are not going to get as good a picture. Once you crank down the fake iso number as much as it will go, and have the shutter as fast as it will go the only thing left is to reduce the amount of light. I measured the work surface at over 2500 foot-candles (meter maxed out) with 4 x 150 watt bulbs light.

There is nothing wrong with the lm4040. Its just that it is 90% or more of the total noise in the circuit. The linear lt1021 is a much better part. Its also 5 times the cost. I'm trying to figure out what is going on. But i have a new camera toy to play with.

So this thread is like the "post the last thing you bought" thread except the rules are that you had to dumpster dive for it. Here is my latest find http://gilmore.chem.northwestern.edu/mp4-1.jpg http://gilmore.chem.northwestern.edu/mp4-2.jpg absolutely over exposes the camera even on iso 150 and f32. 4 x 150 watt flood. Less lightbulb soon.

i'm much more interested in the soon to be released D4.

Yes a pair of 450 volt caps in series on about 625 volts of raw unregulated DC. Has to be this way as 650 volt electrolytics are very custom items and i have not seen any in quite a long time. In fact the 500 volt electrolytics (550 surge) are very hard to find these days. The resistors balance the leakage currents. Which is why the center tap is a reasonable idea.

done

isolation between inputs may be an issue. feedthru does occur and for some of the switches, protection diodes will short the input to near ground with the power off.

That is a pretty accurate description of the differences.

our friendly monk has decided to build a second unit. One T2 is not enough

The ones that andy used were 50mm, and they just barely fit. You have to cut down the 3 front top screws to exactly .250 Better idea is to use the 45mm caps.

monastary off the northern coast of italy? was on 60 minutes recently.

The chrome jacks have to be machined down a bit otherwise the plug won't fit in all the way. Pictures were posted many moons ago. They are still slightly off size. My jacks are the exact right size, i will have to make more in the future. here is the print should someone want to make a bunch of them http://gilmore.chem.northwestern.edu/staxout3.pdf

Thats the things. Even better in carbide. Just about impossible to get those things to walk.

this is closer now, assumes the on board heatsinks http://gilmore.chem.northwestern.edu/kgsshv.xlsx

This is why GOD invented centering drills. Even with my NC machines good for .0005 inch positioning, without using the centering drills first, the wander is horrible even when clamped to within about .5 inch of the end of the drill bit. The problem with manual methods is first you have to use the centering drill on all the holes, then go back and actually drill them. Without a DRO, this takes a lot more time because you have to change the centering drill and the real drill bit for every hole unless you are confident enough in your positioning.

dynahi power supply board that fits on the side of a pesante case. redesign similar to sigma22 by Ti kan. current limiters, precision regulators, fixed 30 volt design, single center tapped transformer... http://gilmore.chem.northwestern.edu/dynahipowerschem.pdf http://gilmore.chem.northwestern.edu/dynapower2.jpg http://gilmore.chem.northwestern.edu/dynahipower2.zip

kerry's thing cannot do the kind of drilling and tapping necessary. On the other hand, nate has a desktop with DRO. Perfect for using a center drill on all the holes (required) and then drilling the holes. Tapping by hand is absolutely no problem as long as you have a chunk of metal at least 1 inch thick already drilled with the exact body size of the tap. Only way to keep the tap straight. And if you keep the tap straight, you won't snap it. I have a mill at home without a DRO, so i do it the old fashioned way and pay attention to the knobs. The NC machines just make it easy and fast.

Those heatsinks absolutely do have to be NC drilled and NC threaded. At a minimum a desktop manual mill preferably with digital readout. No way to use a hand drill. Its unlikely that the .5 inch spacing is going to line up with the fins, so no way to put nuts on the other side.

the hifi2000 case is instead of justin's heatsinks, not in addition. The 3U case should be big enough for one amplifier mounted to the side of each heatsink and the power supply board on the bottom. Two smaller power transformers or one bigger one. I'll be ordering one of these chassis soon. From birgirs dimensions, everything should just fit. But just barely. Justin's heatsinks would be used for a completely custom case, and this is a whole bunch of work i don't want to get involved in at the moment.