[volt-nuts] How can I make a 2000 V DC meter with an input resistance of at least 100 T ohms?
Many years ago, there was an article (in Popular Electronics?) that needed a very high value resistor. They built it by drawing a line between two terminals with Higgins India Ink. No idea if the ink is still made the way it was 50 years ago... > So how does one make ones own resistor? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Bohnenberger electrometer
The 3M model 703 static electric field measurement gun can measure the magnitude and polarity of a static field.They use a 200 millicurie tritium source and a high resistance circuit to do the measurement. The tritium source is used as an ionization source. It runs off of two 9V batteries and looks like a Buck Rogers ray gun. You calibrate the thing by unrolling a section of tape from a roll of adhesive tape. Adhesive tape is made sticky by exposing it to what amounts to a Tesla coil during the manufacturing process. We used to make electrets by charging a disk of carnauba wax with high voltage. There was an article (in Popular Electronics?) back around 1970 that told how. https://www.youtube.com/watch?v=1DR-tTU8uIM ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Shorting straps for test equipment banana jacks
Oops... should have said 0.8 mm and not 1 mm. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Shorting straps for test equipment banana jacks
I got in my latest PCB based shorting straps for test equipment banana jacks from OSHPARK. You can find them here: http://www.eevblog.com/forum/metrology/copper-binding-post-shorting-straps-for-low-thermal-emf-alloytempering/msg1389056/#msg1389056 ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Banana jack shorting straps
Mine have 2 oz copper on each side and some via stitching between the sides. I am waiting for the prototypes from OSHPARK to determine if / where I can add additional vias without compromising the structural integrity by creating "break me here" fault paths. I have a 4-way layout in the works (basically the same design with longer "legs" that will reach to the other pair of jacks. Unlike the Fluke one, I don't have any solder mask on mine. Different banana jacks have different sized contact disks and if you get the solder mask too close to the slot it can keep the jack from making contact to the copper / ENIG gold. -- That said, the 8508A-7000K board has thick, wide traces on BOTH sides for the current and sense terminals and a smaller trace bridging sense to current ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Banana jack shorting straps
If the two wire straps work out, I will probably do a four wire short. When I need I four wire short (which isn't very often), I usually just use a freshly stripped piece of copper wire. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Banana jack shorting straps
It's basically an "E" shaped PCB around 15x35mm that can be used to do things like short between sense and drive banana jacks. - > I'm trying to imagine what you are describing - is this PCBs with 4mm banana > plugs installed or a small PCB with two slots at 3/4" centres to match the > socket spacing? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Banana jack shorting straps
The main use of these would be shorting sense to drive jacks. They could also be used for input shorts. The advantage over bare copper would be the ENIG gold finish... bare copper quickly forms oxide layers and copper oxide has a horrible thermal EMF. Granted, ENIG gold basically involves waving a bar of gold over the plating tank and hoping some gold atoms fall off. The board house I use deposits a thicker layer than most. You don't want to know what "hard gold" finish would cost. Using a PCB house to fab them is probably 20 times less expensive than having a machine shop do them out of solid copper... maybe 50 times less if you need to get them gold plated. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Banana jack shorting straps
Recently on EEVBLOG there was a thread where a guy mentioned that he was going to machine some shorting bars for banana jack out of copper. I made the suggestion to gold plate them to avoid copper oxide issue. Another guy mentioned making them like a PCB (like Fluke does). I did a little thinking and checking and am going to have some built. Probably 0.8 .. 1mm FR4 core, 15x35 mm, double sided 2 oz copper, ENIG gold finish. Anybody interested in some? Fab cost goes down rather quickly with quantity. Cost target is maybe $10 for 10 pieces shipped.OSHPARK cost would be around $5 for three boards on 1.6mm, 1 oz copper. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Extenders for the Datron 4800 series of calibrators?
I think you may be paying to much... check out the pricing at gojgo.com They do excellent work for very low prices. Also check how the price varies with quantity. Often you can get 5X the number of boards for a 20% increase in total price (excluding shipping). > back in 2011 I had 25 extenders of a similar size to the large boards made and the unit cost was USD28. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Current Button for Datron calibrator (4800, 4805, 4807, 4808)
I used to make button / keytops by making a mold of a compatible one in clay or silicone rubber and filling it with epoxy followed by a lot of fiddly work carving out the interface to the keyswitch plunger. These days 3D printers are your (frustrating) plastic pal who's fun to be with. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] PCBs with ceramic substrates
Not always.. A guy I worked with was pulling a ceramic 40 pin dip out of a socket when it broke... sliced his finger to the bone. There was initially some concern that it was a BeO ceramic. Checking with the manufacturer showed it was not. I checked the socket afterwards, and it seemed normal and had no problems releasing other chips. > You really have to work to break these things. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] low emf solder
Once you get past 99.99% purity funny things begin to happen... I have some 100% pure Cu oxygen free cable (says so right on the jacket) made in China that is magnetic! You can't do that with the cheap stuff, now can you? ;-) Oh, and it is so pure that it has three times the resistance of normal 99.99% pure American copper. The US is so far behind China in the art of bogo-physics, I fear we will never catch up. -- If you go for the oxygen-free variant you can get to 99.99% (don't ask me whether the audiophool grade is really that pure) ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] low emf solder
When making the CdSn solder you want to avoid contamination with other metals. It doesn't require much contamination to lose its magic foo powers. So no metallic molds or tools used. And what, no shaved cadmium with a Bordeaux garlic reduction? Try it, it's delicious ;-) ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] low emf solder
I don't know if it the proper way but I used a very nice fume hood. Measured the metals (high purity), melted them in a quartz crucible, stirred with a quartz rod, and cast it in a ceramic block with a spiral pattern machined into it with a ball mill. You don't want to contaminate the mixture with other metals, etc. That "Things I Won't Work With" article was about dimethyl cadmium, not metallic cadmium. Reall Nasty Stuff. Metallic cadmium and cadmium plating has been used for ages without killing too many people. It's not something to take lightly, but I've had the pleasure of working around far worse things. For even more extreme nastiness check out dimethyl mercury... one drop, goes through rubber gloves like they aren't there, sure-fire rather horrible death. Derek Lowe's "Things I Won't Work With" series is some of the best reading out there... Unfortunately, I don't think that he is still doing them. His old web site has disappeared. Just checked... Derek is at it again after a two year hiatus... woohoo! He's my favorite chem-blogger. Something makes me want to play with all the things he won't work with. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] low emf solder
A few years back I whipped up a batch of Cd/Sn solder... but I had access to the proper equipment to do it safely. And no, you can't have any! ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] 1PPS to 32.768 khz
Yep, a single 8-pin chip with 4 pins used (VCC, GND, in, out). I did something very similar to this in an ATTINY-13 (OK I used a TINY85, but the code was less than 200 bytes long). I can't share it since somebody paid for the thing and it is not directly applicable, but it is rather trivial to do. If you want to get fancy, you can have the thing self-calibrate the pulse generation loop to optimize the output pulse timing to minimize the "dead time" between the last pulse out and the next 1PPS pulse and compensate for RC oscillator drift/variation... but that is an unnecessary complication for a wall clock display. Just hard-code it and leave enough margin for device variation/drift. --- > Some of them come with builtin R-C oscillators so the parts count would be > really low. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Is there a "standard" much better than a LTZ1000, but much cheaper than a Josephson Junction Array?
At one time I came across a Russian company that was selling JJA's based on high-temperature superconductors (liquid nitrogen cooled). They had both JJA chips and complete systems. They were not quite as good as the helium cooled devices but were quite a bit cheaper and easier to work with. Apparently the grain boundaries of the HTS material was a source of noise. I can't find the reference to their company at the moment... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] fluke 731b battery pack
Most NiMH cells have a capacity of around twice what a NiCad has, so a NiCad charger that works at a C/10 charge rate will be charging NiMH cells at C/20. That can be an acceptable trickle rate for NiMH cells, but I prefer something in the C/40 neighborhood. I put some in an electric shaver (really crude charger) and they last longer than NiCads. Proper low self discharge NiMh cells have about 1/10th the self-discharge rate of NiCads. I have some in some test equipment that seldom gets used and after over a year of storage were still going strong and provided hours of run time. NiCads would be dead after a couple of months of storage. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Thermal EMF of common solder
Several years ago I made my own CdSn solder... I had access to a proper chem lab with fume hoods, etc. And no, I can't supply any and won't be making any more. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Best Rubidium Frequency Standard
Mark's Law of Rubidium Goodness... the bigger the box, the better it is. The HP5065A is one of the best units ever made. It can rival a cesium beam unit. The X72 is a horrid little creature. I would also go with the M100 / FRK units. The LPRO an FE56xx units were designed for telecom use and meet the specs required of them and low cost. The M100 and FRKs saw a lot of use in military systems. Which one you choose is best determined by your budget, applications, and requirements. A noisy little X72 could be just fine, or you may need the beastly HP5065. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Oldaker is no more...
I stopped by my favorite electronics store to buy some more Oldaker meter probes. Alas, I was told that Oldaker had a fire and is no longer in business. They were a small (7 person), family owned business that made really nice and affordable test leads. Apparently they don't plan on restarting the business. I've used their leads/probes for years and have never had one fail. And the tips are damn sharp... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Low-cost voltage reference questions
Egad, I just read through that EEVBLOG thread... now I need a mind enema... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Differential amplifier >=1Mhz
Maybe a Tektronix AM502 module and the single slot TM501 mainframe? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Anyone know how to make stable inductors?
It's a lot harder than making stable capacitors... particularly for low inductance values. I think the process involves the use of rainbow flavored unicorn tears. There are some 0.01% standard inductors on Ebay starting at around $400 each. Also some .1% ones for a lot less. Decent L measurements are a cesspit of traps and gotchas... things like L shifts with current, frequency, moon phase are just the start. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Precision resistors - Fluke 5450A
One thing to watch out for on the 5450A is burned out segments in the 14-segment LED displays. The display chip they used is rather weird (each 14 segment digit is actually two 7-segment displays mixed together) and VERY unobtainium. Mine has a missing segment on one of the digits and I have not found any replacements in 5+ years) The display is not critical to operation and my missing segment does not cause any digit ambiguities. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] How accurate is a fluke after 9 years
Think twice about those Vishay metal film resistors... they have known stability problems (particularly concerning humidity). Also they can have problems meeting their own specs. There is an active thread of eevblog.com concerning the issue. Consensus seems to be precision wire wound resistors are a better choice. These will be replaced by 2 vishay 0.01% resistors which are hopefully more stable. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Need help with old Tek scope
Probably a wonkey electrolytic cap... In the old TV days, this was usually caused by a coupling capacitor, not a filter capacitor. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] plastic caps on 3458A reference board
Most low-end 3D filament printers can print in either PLA, ABS, or even nylon. PLA prints are known to distort in a hot car. ABS is extruded at around 250C. I think nylon is a bit higher. I would think that ABS would work well.There are now some low-ish cost (like under $3000) stereo-lithography printers available that print by scanning a liquid resin with a laser. Some of those resins are good for higher temperatures. The low end resins have a glass transition temperature of around 100C. Another possibility is to make a mold and cast the parts out of epoxy. Epoxies that can handle over 400C are available. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A cal ram data dumper program
John Miles has included my HP-3458A cal ram data dumper program in the latest release of his excellent GPIB Toolkit package. You can download it from the KE5FX web site. The released version produces the formatted listing of the various cal RAM values in its output (it is the same version of the data dumper that I put up on tinyupload.com). ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Build your own watt balance
Using Legos! http://arxiv.org/pdf/1412.1699v2.pdf ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Design Spark PCB Design Package
Another program that is supposed to be very nice is DIPTRACE. Their free version is limited by pin count... Eagle's free version is limited by board size. Eagle has more community support than the other packages. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A cal ram data dumper
I have uploaded a .ZIP file with the source code and Windows .EXE file for the calibration/data memory data dumper program here: http://s000.tinyupload.com/index.php?file_id=0219779600667150 This output of this version of the program also produces a formatted/commented listing of what the various data values in the cal ram are. Program usage info is available by executing the program without any command line arguments. Also see the comments at the start of the .CPP source code file. Again, this program is to be used in conjunction with John Miles GPIBKIT library. Also many thanks to Poul-Henning Kamp for the hard work of documenting the HP3458 MREAD command and for figuring out everything about the cal ram memory map and contents. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A cal ram data dumper
Yes, the program requires GPIBKIT. Copy the code to the GPIBKIT directory. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A cal ram data dumper
It's only for the 3458A. Unless you want to play with the code, you only need the pre-compiled .EXE in your GPIBKIT directoty. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP-419 and Fluke 845 Modifications
Eagle has a freeware version that is for non-commercial projects of smaller physical size. It is a very stable program... it has never crashed on me. Eagle has LOTS of community support. All the PCB services that I mentioned can fab boards directly from Eagle .BRD files so you don't even have to mess with making Gerber files. They all have a preview function, but OSHPARKs is the best. You can submit files to OSHPARK, preview them there, and not submit an order if you just want to verify your design. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] PC board layout software [WAS: HP-419...]
Another package that has a good reputation and is fairly inexpensive is DIPTRACE. It is supposed to be easier to learn than most packages. Their size limits are based upon pin count, not board size. Their non-commercial free version is limited to 500 pins/2 layers. A local university recently evaluated several programs and chose DIPTRACE. I've never seen a real PCB package that did not have a rather steep learning curve, lots of frustrating warts, etc. Having a decent sized installed base and active community is essential... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP-419 and Fluke 845 Modifications
OSHPARK.COM is in the US and will do three boards for $5/sq inch... with no setup or shipping charges. For larger boards or quantities dirtypcbs.com and gojgo.com make nice boards for dirt cheap (particularly for boards under 5x5 or 10x10 cm). They can be 1/10th the cost of OSHPARK. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Precision resistor testing
Just for grins I asked IET what it would cost to calibrate my SR104 resistor and they quoted something like $1000. I did not respond and a couple of weeks later they sent an email along the lines of Hey if that was too much, let's talk... we can work out a price... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] 732A rear panel battery connector
Yes, I have laid out a pair of boards that has the battery module circuits on them. One board plugs into the mainframe (it has the thermistors on it) and the other has the rest of the circuitry. I have not ordered them yet... I need to buy the festoon lamp connector and have been waiting until I have to order some more parts from Mouser. What I didn't do is try and build the whole battery module with all the mechanical parts/frame/etc. I may laser cut a back panel piece, though, out of acrylic. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] TM500/TM5000/HP-5370 Extender cables and cards
I suspect that 90% of the work could be done with a single kit. That will get one card out of the chassis. But, there are always those annoying problems where getting two cards out can make life a little easier. With two kits you could also hack up the extra 44-pin board to make a smaller board (or boards) for getting the odd-ball cards out (if you can find the required edge connectors). So far, I've only needed to do a single card... I suspect most TM500 people will want two cables, but that depends upon what modules you have. Most modules just have one connector. Some of the fancier ones use two. And a very few use three. I even have a custom module that has 4... At first, I didn't think that the TM5000 GPIB extender cable would be all that important, but I have wound up using it several times. -- Hi Mark - do you recommend one 5370 Extender set or two? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] TM500/TM5000/HP-5370 Extender cables and cards
The TM500/5000 and HP5370 extender kits are now available (actually they were ready a few weeks ago, but I was going to be out of town and did not want to leave people hanging).Prices are:HP5370 extender card kit - has 2 x 36 pin extenders and 1 x 44 pin extender. $30 setTektronix TM500/TM5000 module extender cable kit - $20Tektronix TM5000 GPIB extender cable (assembled) $20US shipping is $6 for any number of kits. International shipping is $15 for any number of kits. If you need international tracking they must go registered mail which adds another $15 (and slows down the mail) or express mail which is stupid expensive. All kits include everything you need to get going except solder and basic tools.Email me for my Paypal address.The HP5370 extenders are 5 inches long.The TM500 kits include a pair of 17 40 pin IDE ribbon cables. You may want to use your own, longer cables. The TM5000 GPIB cable is around 28 long.Remember that some TM500/5000 modules require 2 or 3 extender cables... I even have one that needs 4, but it is a one-off custom design. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] 5200a extender
The tightest clearances are where an etch runs between two pin on the ribbon cable connector. The connector pin are spaced 0.10 apart. The pads are .060 octagonal pads so edge-to-edge is a .04 gap. A .016 trace runs in that gap. So there is a .012 clearance between the pad edge and trace. Worse case would be 300V bridging that gap, but the Fluke edge connectors are set up so that (I think) the highest potential difference is 190V (between the +/-190V lines and GND. There is a possibility of +300V and a signal called /LIMIT. The layout/pad sizes could be tweaked some and that .012 gap could be increased to maybe .020 A board layout that didn't run etches between pads is not practical and/or would require a board size that exceeds that permitted by my CAD program (or requires a $1700+ upgrade). So what's the safe arc-over distance for 300V on a G10 circuit board? The ATTEN, PWR AMPL, and PWR SPLY boards all have the high voltages on them... and they aren't on the same pins... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Does anyone have a 3458A CalRAM dump routine in C ?
I tried to send you a copy of my program, but the email bounced... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Finally got around to modifying my Fluke 845ab with LED's
BTW, you can get LEDs that are designed specifically for flash applications. They can handle high peak currents, have decent color spectra, and/or fast rise/fall times. There are also LED driver chips made for flash applications. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Finally got around to modifying my Fluke 845ab with LED's
I would probably use green or yellow LEDs, but the white ones should not be a problem. I built an LED analyzer/integrating sphere and one of the features is a circuit that optically measures the LED driver PWM frequency. It can also detect the minute variance in LED intensity from an LED driven by a 950 kHz boost converter. It also had no problems with a white LED driven at 4 MHz from a signal generator. You see the long persistence phosphors mainly in large lighting LEDs and not in small indicator LEDs. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Finally got around to modifying my Fluke 845ab with LED's
No web page, but a little description here. It has changed quite a bit from the original description. Now uses TAOS color sensors. Suppors Melexis IR thermometer chips. Has 16 bit A/Ds. Processor is an ATMEGA 1284. The control program is based on Lady Heather. Besides LEDs it can also charge/discharge/analyze batteries, measure power converter/supply efficiency, etc http://budgetlightforum.com/node/12296 CIrcuit board: http://img69.imageshack.us/img69/3782/luxor.png Sphere in action: http://img515.imageshack.us/img515/4288/spherew.jpg BTW, the PWM sensor is a silicon phototransistor with not much blue light sensitivity... - Do you have a web page on the LED analyzer/integrating sphere? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Fluke 5200A extender board.
5200A extender cables are a go! Connectors and boards are on order (from a different board fab in Hong Kong this time). One board goes on each end of the extender. Boards are connected by a 50 pin and 40 pin ribbon cable. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Fluke 5200A extender board.
Those are not holes... they are polarity markers on the silkscreen for the connectors. I do have one concern about doing the extender with ribbon cable. It is rated for 300V and three of the card slots do have 300V on them. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Fluke 732A battery module (and possible circuit replacement)
I have a 732A that is missing its battery module. Does anybody have or know of a source for a replacement? Also, would there be any interest in a replacement circuit assembly for the battery module? It would probably consist of a small board that plugs into the 2x6 pin edge connector and another small board with the ballast lamp/diode/resistor/thermistors and connections for the battery/switch/external power jack. The two boards would be connected by a short ribbon cable and would allow one to add batteries to a 732A that is missing the battery module. It would not be a complete battery module with the metal frame and backplate... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Fluke 732A battery module (and possible circuitreplacement)
I thought about a lithium pack, but that would probably require a new power supply board or extensive mods to the current one. The charging system for lead-acid batteries and lithium batteries is quite a bit different. Not sure what it would take to reliably/safely cobble a lithium compatible charger system onto the Fluke lead-acid circuit. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K memory chips?
I'm porting over my HP3458A NVRAM data dumper program to use John Miles GPIBKIT routines. It should make it usable with most GPIB interfaces out there and be able to run under more modern versions of Windoze. My first crack at it is working, but it is quite a bit slower than my original program. Not sure if anything can be done about that... BTW, my program does verify the checksum bytes in the CAL ram so there is a check that the dump went OK. Without Poul-Henning's work none of this would be possible. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A CAL ram data dumper program
I have the GPIBKIT version of my HP3458A cal ram data dumper program available. If you want to try a copy shoot me an email. If it works out, I'll see if John wants to include it in the standard toolkit distribution. You will need to download GPIB tool kit from the KE5FX.COM web site, run the tool kit configuration program (PROLOGIX.EXE) to setup it up for your interface (it works with Prologix and NI compatible interfaces), copy my HP3458.EXE program to the GPIBKIT directory and run it. Check the comments at the start of HP3458.CPP for some info. Run HP3458.EXE without any command line arguments for program usage help. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A CAL ram data dumper program
The program outputs a 2kB (or 2 x 32kB) binary ROM image files files along with a couple of ASCII format files of the data. 2kb for CAL ram and 32kb for DATA ram (probably not needed, but it can dump the data RAM chips). The binary files have the extension .hi and .lo (CAL ram data is only in the high byte of the memory space). ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K memory chips?
You REALLY don't want to mess with that 24 pin NVRAM chip... it contains the calibration memory. If you bugger the data in it, you get to spend a couple of grand getting the meter back into working order. I know a couple of people that did just that. The solution is to first make a backup copy of the memory contents using the (undocumented) MREAD command over the GPIB bus. Poul-Henning Kamp figured out how to do it... buy the man a beer... even better a case of beer... Search the archives for details. I just backed up all the memory in my 3 HP3458A's for when the inevitable BIG BAD DAY comes and the backup batteries go bye-bye. If you happen to have a NI GPIB-232CV-A (or possibly a Prologix) RS-232 to GPIB converter and can run a DOS or WIN98 program, I have a program that dumps the memory chips. It has code for the Prologix in it, but I've only used it with my a Prologix compatible unit I built... I don't have a real Prologix to test it with. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K memory chips?
The problem with removing the chip and copying it is the very real chance of glitching the contents in the process. Much better to make a backup copy first. The 32Kx8 NVRAMS are used for system memory and things like storage of user programs and data. Note that the two 32Kx8 devices are form a 16-bit word. The 2kx8 cal ram is only on the high byte of the data bus. MREAD returns memory contents as a signed integer value (-32768..32767) in ASCII. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K memory chips?
Why risk having to re-cal the meter? There are several GPIB-232CV's on Ebay right now... Two of them are under $60 Buy-It-Now... cheap enough to be worth trying. The Prologix USB converter is around $100... $150 new from the factory. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] A cute doohicky
I recently bought a couple of these gizmos: ($19 bucks a pop) http://www.ebay.com/itm/261527017059?ru=http://www.ebay.com/sch/i.html?%3Cem%3Efrom%3DR40%26_sacat%3D0%26_nkw%3D261527017059%26_rdc%3D1 Stick in a semiconductor/r/l/c/etc, press the button, and it tells you what it is, the pinouts, and relevant parameters. Works amazingly well. They are based on an open-siource design discussed here. http://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/ It is well worth reading the documentation: http://www.avrtester.tode.cz/upload/ttester_en.pdf A very good example of what some VERY simple circuitry and VERY clever coding can do. The firmware is being constantly upgraded. The units with the cruder character mode LCD are lot more amenable to firmware upgrades than the graphics mode LCD ones that I bought. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A calibration memory backup
The HP3458A MREAD command returns a 16 bit value as a decimal integer. The 2kB cal SRAM is only 8 bits wide and the values are returned in the high byte. On two of my machines the low byte is always B9 hex. One the other one (earlier serial number) it is always FF. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A calibration memory backup
I did some more playing around with the 3458A memory dumper this weekend. I built up another system using a different computer/cables/software/GPIB interface (one I built using an AVR chip that emulates the Prologix RS-232/USB converter). I noticed than a couple of dumps of the CAL ram (out of maybe two dozen runs) had one byte near the end of the RAM (in that same string of 01 bytes) sometimes read as 00 or 05. This was with a different 3458A and it has been continuously powered for a couple of days. Perhaps the memory chip is not enabled at those addresses and it is reading a floating bus? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Tektronix TM500 extender cable kit
I got in my prototype extender cable boards from OSHPARK.COM today. OSHPARK only builds boards in multiples of 3 and I only ordered three boards so could only build one cable. It seems to work very well. I tested it with several different TM500 and TM5000 modules (using another set of cables I have with the dual and triple wide modules) and they all worked fine... including some real power hogs like a Ball Aerospace rubidium oscillator. I have a bunch of circuit boards of a different design on the way from a new (for me) Chinese vendor. If they look good I'll order a couple hundred of the extender boards (it takes two boards to make one cable). I have also pimped out the original extender board silkscreen and added an LED to the +11.5V supply. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458A calibration memory backup
I have three HP3458A's and decided it was time to back up the battery backed static RAM chips. I wrote a program to dump the RAM contents over the GPIB bus using the undocumented MREAD command as documented by Poul-Henning. I dumped both the 2kB CAL rams and the 32kW auxiliary data RAMs (hopefully that data is at the addresses mentioned by Poul-Henning. I used a NI GPIB-232CV-A RS232 to GPIB converter as the interface. All seems to have gone well and the CAL data looks reasonable. As a check I dumped all the data from each machine three times and compared each dump... each CAL data set matched except for the third machine. On the first two, the units were powered on for a couple of hours while I tweaked with my code. I dumped the third machine from a cold start and one byte was different between each dump. I waited a couple of hours and tried again, this time the data dumps matched. It looks like that byte may be being updated while the machine warms up... If you dump your machine's data, it might be a good idea to let it stabilize for a couple of hours first. The dumps of the 32kW of aux data have several words that change between each dump. It looks like that memory has some uses by the firmware other than storing user data, etc. I think when the time comes to replace the battery backed memory chips I may try Cypress/Ramtron FRAM chips or Simtek STK16C88 AutoStore devices. The Simtek chips are available in 28 pin DIP packages that appear to be drop-in replacements for the DS1230 chips. The DS1220 chip would require a SO8 packaged part on a carrier board. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Tektronix TM500 extender cable kit
A few people have asked what the extender board looks like. Attached is a rendering of the board. The same board is used on each end of the cable. One of the boards would have the edge connector soldered to the top, the other plugs into the mainframe. Two 39 or 40 pin ribbon cables connect the two boards. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Another LED display wanted...
I am looking for some (well at least one) DL02614 dual character 14 segment common cathode LED display modules. These were used in the Fluke 5450A resistance calibrator. They were made by Litronix and maybe Siemens. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Another LED display wanted...
Yeah, and it's a weirdo too. Each digit is built as two seven-segment displays, so there are two cathode lines and 7 anode lines per char. All the current 7 seg displays have 14 anode lines per char. I've thought of doing a replacement front panel board (probably using a micro and LCD display), but only one segment is bad and it does not affect the usability of the display... too much work for now. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Another LED display wanted...
Is one used as an exponent, and doesn't need all segments to work? Nope... no joy there... The missing segment is the top segment of one of the digits. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Valhalla 2720GS
Valhalla is still around.. I've purchased manuals from them (a bit pricey, low quality repros). Email or call them and ask. But on a couple of their products they have disavowed all knowledge of their existence... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] What made a HP3458A so expensive
Some Russian company has a JJ standard that uses high-temp superconductors and liquid nitrogen cooling. Because of things like grain boundary issues in the HTS, it is not quite as good as a 4K cooled unit. - Of course at the present time given the fact that the JJ has to be cooled to below 4.2 K makes this idea more than a little impractical ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] What made a HP3458A so expensive
One problem with leaving the 3458A on all the time is the vacuum fluorescent display. These have a rather limited lifetime and leaving them on 24/7 puts a lot of hours on the tube. Someday those displays will become unobtainium... ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] any unheated Vref better than LT1021-7 (at 7 ppm/khr typ.) ?
Take a close look at the photos of Malones nice little voltage reference boards (http://www.voltagestandard.com/Home_Page_JO2U.html). The voltage reference chip is mounted on an isolated peninsula of PC board material to help isolate it from stress due to environmental changes. If the humidity effect is strictly from mechanical stress on the die as the plastic encapsulant swells or shrinks, would a part in a metal can then be immune from this effect, even if it was non-hermetic? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] ESI 2100
A common fault with these is the Mostek CPU/peripheral chips on the motherboard. The pins corrode away. Another common fault is with the video monitor. I had one where the socket on the CRT was bad... intermittent connection to the filament. Another blew a couple of transistors. Also the pots needed to be cleaned. ManualsPlus.com has the service manual... $70 ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
