kevin gilmore

fixed duplicates on the schematic. also a few other things that got to the board and were not on the schematic. pathetic parts list here. QTY PART-REFS VALUE --- --------- ----- Resistors --------- 4 R1,R9,R21,R22 300k 4 R2,R3,R13,R14 15/3W 2 R4,R17 50k 4 R5,R15,R29,R30 440k 2 R6,R16 20k 4 R7,R10,R18,R20 240k /3W 2 R8,R19 650 4 R11,R12,R23,R24 500k 2 R25,R26 2K 1 R27 787k high voltage resistor subject to adjustment depending on transformer 1 R28 15k high voltage resistor subject to adjustment depending on transformer 1 R39 3000 2 R40,R42 100k 1 R43 5M Capacitors ---------- 4 C1,C4,C5,C9 680uF 6 C2,C3,C6,C8,C12,C14 100uF 2 C7,C17,C19,C21 .1uf /1000v 2 C10,C15 .22uf /1000v mouser 5989-1KV0.22-F 2 C11,C13 4700uF 2 C16,C18 1000pf /1000v Integrated Circuits ------------------- 1 U3 7815 1 U4 7915 Transistors ----------- 4 Q1,Q2,Q11,Q12 fqpf8n80c 4 Q3,Q4,Q15,Q16 2sc3840 6 Q5-Q7,Q17-Q19 2sa1486 2 Q8,Q20,Q2 10m90s 4 Q9,Q10,Q13,Q14 2n3904 Diodes ------ 2 D1,D6 24V zener 6 D2,D10,D12,D13, 1n4007 D21,D22 4 D3,D4,D7,D8 200V zener 2 D5,D9 100V zener 3 D17,D18,D20 150v zener 1 D19 130v zener Miscellaneous ------------- 3 BR1-BR3 BRIDGE which is actually 8 individual diodes and one bridge 2 REF,REF2 lt1021-10 high voltage resistors are mouser hvr3700007153fr500 http://www.vishay.com/docs/30260/hvr25.pdf ALL HEATSINKS ARE GROUNDED. The ixys parts must be mounted on the ceramic insulators and secured with a non-conductive screw. Others that have built the previous version had this problem, then lots of parts blow up. You can trim this power supply for minimum heat. For the 450 volt version, the zener string should be 500 volts and the unreg can be as low as 550 volts. Then it will work at 10% low line. If you want something that works 15% low line, bump the unreg to 600 volts. Since its a crap shoot on getting transformer manufacturers to actually meet specs you give them, its up to you to pick the appropriate unreg high voltage AC. But something like 420 vac under load works. You can easily change a few parts and go to 500 volt outputs. Bump the zener string to 550 volts, and unreg to 600 volts. at which point you don't need the voltage multiplier and can jumper around it for the bias.

many thanks to kerry on this. http://gilmore.chem.northwestern.edu/kgsshvps8e.pdf http://gilmore.chem.northwestern.edu/kgsshvps8e.jpg

Updated power supply board. Can run on less unregulated voltage, and has a multiplier for the bias. Parts reduced a bit, and a easy way to build it as a dual zener supply only. http://gilmore.chem.northwestern.edu/kgsshvps8e.zip

birgir's unit up and running. Evidently he has a noisy pot in one of the batteries, same as the problem andy had. Must be a large batch of bad trimpots.

all nighters and high voltage are a bad idea.

There is at least 2 different kinds of the input tube sockets. On the ones i used, the center pin had no bushing, and fit thru the board completely just fine. You put the 8 pin sockets in as far as they can go. On the 9 pin sockets you align them so that they barely fit thru the circuit board. Then the top of the octals and the 9 pins are close to the same height.

the stax jacks were aligned to the inside edge of the extrusion. you should be able to move the jacks down but i'm not going to take mine apart to make sure.

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