HP Forum Archive 13

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Any Interesting HP 3421A applications out there? Message #1 Posted by Tracy Vermeyen on 22 Aug 2003, 12:54 a.m. I was wondering if anyone wanted to share some interesting HP 3421A applications using the HP 41C calculator as the controller? I've heard of someone using this system to run a sprinkler system and I want to know more. Tracy

Re: Any Interesting HP 3421A applications out there? Message #2 Posted by Vieira, Luiz C. (Brazil) on 22 Aug 2003, 2:44 a.m., in response to message #1 by Tracy Vermeyen Hi, Tracy; some contributors in here have 3421A units, and I'm about to get one myself. Do you know what I'm actually interested on after taking it? Build custom boards. Anything, since collecting specific data to external actuators. The unit I'm about to take has only an input 10-ch board (or would it be 8-ch?). Anyway, do you know if there is any documentation about how to design custom boards for it? is there any information about internal bus and the like? Just curios about. Another thing: it seems that the HP41 becomes a fine controller for the 3421A when the specific 3421A ROM is installed. Do you have it? I plan to use mine (to come soon, I hope) with the HP71B or, if and when is delivered, an HP75. I think these are better controllers, not because I take as better than the HP41, but because they have a bigger display and bigger internal RAM, allowing more data to be recorded without the need for external mass storage access so often. Are you interested only in applications with the HP41? Best regards. Luiz (Brazil) Edited: 22 Aug 2003, 4:04 a.m.

Re: Any Interesting HP 3421A applications out there? Message #3 Posted by Tracy Vermeyen on 23 Aug 2003, 1:07 p.m., in response to message #2 by Vieira, Luiz C. (Brazil) Luis, Yes, I do have the 3421A ROM module and it makes using the 3421A quite simple. For now I am only interested in 41C applications because that is the only system I have (for now anyway). I have access to a full line of documentation for the HP 3421A in paper form only and it would be alot of work to convert it to PDF. Sorry, I do not have any specific information on creating custom boards. I can look for information on the internal bus, do you have any specific questions? Regards, Tracy

Re: Any Interesting HP 3421A applications out there? Message #4 Posted by Christoph Klug on 22 Aug 2003, 5:15 a.m., in response to message #1 by Tracy Vermeyen Dear Tracy, some weeks ago I sold a HP-IL/PC interface card to Technologie Center in Karlsruhe/Germany. They use some HP3421 - controlled by PC (not HP41) for water quality measurement. But I have no detailed informations about the sensor systems they use. I have also an HP3421 - but for measurement,data logging and interfacing applications I prefer my modular I/O-Board and my new IL2000 system. This include some more features and less space than the HP3421. As system controller I use the HP41CX including EXT-I/O Module and CCD-Module. Applications are audio measurement, temperature measurement.... Best wishes - Christoph

Re: Any Interesting HP 3421A applications out there? Message #5 Posted by Christoph Klug on 22 Aug 2003, 5:25 a.m., in response to message #4 by Christoph Klug Dear Tracy and Luiz, some details about the HP4321 including service manual you find on the webpage of Warren Furlow. Including a describtion of the 8 bit input-output option board. Have anyone practical knowledge about calibrating a HP3421. Please give details about this procedure to the forum . Best wishes from Germany - Christoph Klug

Calibating 3421 Message #6 Posted by Renato on 22 Aug 2003, 6:29 p.m., in response to message #5 by Christoph Klug Christoph, I have no practical knowledge, but I know that the DC and AC reference voltages are not so easy to get. Also, a 6 digit voltmeter is quite a rare animal. Renato (with one 3421 to calibrate, to send to a great friend).

Re: Calibating 3421 Message #7 Posted by Lawrence on 23 Aug 2003, 8:10 a.m., in response to message #6 by Renato Agilent Technologies (former HP Instruments Div.) will calibrate a HP3421A. I had them calibrate mine. It was determined one of my three multiplexer boards was faulty. Given the age of the unit they could not offer a replacements. The cost of calibration is $US 275 which included domestic shipping to and from my location. Their phone number is 800-403-0801 if you're interested. The best source of info on the unit is Warren Furlow's 3421A CD-ROM. It includes numerous example programs with barcode. I control my unit with a Data Acq / Control ROM image within my HEPAX ROM. Good Luck.

Re: Any Interesting HP 3421A applications out there? Message #8 Posted by Tony Duell (UK) on 22 Aug 2003, 6:44 p.m., in response to message #1 by Tracy Vermeyen I have an HP3421 (great instrument!), but I normally use it with the HP71. That machine has more memory than the 41, which is useful for storing and processing whatever data I measure with the 3421. One application I use it for is testing the HP chargers. It is well-known that the chargers for the Woodstock, Spice, and Topcat series are just transformers, but they're transformers with deliberately high internal resistance. So i decided to do the stand school experiment with said chargers -- connect various resistors to the output and measure the voltage, then plot the V-I curve. Of course I've got better things to do than measure voltages all day long. So I connected 8 relays to the digital outputs of the 3421 (I actually used a ULN2803 chip to drive them, this is probably not necessary, the 3421 could do it directly), and used said relays to switch in the resistors in a 7 stage chain (1, 2.2, 3.9, 8.2, 15, 33, 68 ohms IIRC, with a 10 ohm in series with the lot). The last relay disconnected all the resistors from the charger so i could measure the open-circuit voltage. I wrote a little HP71 program to cycle through the 129 possible resistances (128 settings of the chain, and open-circuit), and record the AC voltage at the output of the charger. These readings were stored in a text file that was then uploaded to my 95LX palmtop (one of the few machines I have with a spreadsheet) to plot the graph. On other thing I did was to use the resistance ranges of the 3421 to measure the resistance of the chain in each of the settings, and saved that on the 71. That way I could get away with cheap 10% power resistors.

Re: Any Interesting HP 3421A applications out there? Message #9 Posted by Vieira, Luiz C. (Brazil) on 22 Aug 2003, 11:58 p.m., in response to message #8 by Tony Duell (UK) Hi, Tony; you know what? That's what I think is one of the best examples of what can be done (amongst lots and lots of things) with an instrument like the 3421A. I thought about charging/discharging battery curves as well; also, Simultaneous/multipoint measuring would be a lot easy. In my previous post in this very thread, I asked about internal 3421A specs. Do you have (or know where I could find) this sort of information? I would like to know if it is possible to build custom boards with ordinary, commercially available components, to be used with the 3421A. Best regards and thank you. Luiz (Brazil)

Re: Any Interesting HP 3421A applications out there? Message #10 Posted by Gordon Dyer on 23 Aug 2003, 10:33 a.m., in response to message #9 by Vieira, Luiz C. (Brazil) Have a look here for info on the HP3421A. Best wishes...

Re: Any Interesting HP 3421A applications out there? Message #11 Posted by Tony Duell (UK) on 23 Aug 2003, 4:12 p.m., in response to message #9 by Vieira, Luiz C. (Brazil) I believe the 3421 service manual is on the web somewhere -- that includes full schematics. I do know that the digital I/O card is all standard components -- it's a bit unconventional since all the inputs and outputs are isolated, but you should be able to make a card that looks the same to the 3421 without all the transformers (!). The mux is a bit harder -- there's a temperature sensor IC for cold junction compensation on that board, so if you homebrew that one you'd have to calibrate it. Not impossible, but not trivial. Again, AFAIK there are no custom chips on that board either.

Re: Any Interesting HP 3421A applications out there? Message #12 Posted by Gordon Dyer on 24 Aug 2003, 11:30 a.m., in response to message #11 by Tony Duell (UK) Sorry but the link I thought I had included to the website was missing, it includes the manuals and brochures for the HP3421A.

Re: Any Interesting HP 3421A applications out there? Message #13 Posted by Vassilis Prevelakis on 24 Aug 2003, 2:47 p.m., in response to message #12 by Gordon Dyer Gordon Dyer wrote: > Sorry but the link I thought I had included to the HP41 website was missing, > it includes the manuals and brochures for the HP3421A. Its bad manners to ignore the wishes of your host. Since David does not want this site to be mentioned here, I think we should all respect his decision. You can always send this info via email. A person who asks for advice but does not include an email address only has himself or herself to blame. **vp

Re: Any Interesting HP 3421A applications out there? Message #14 Posted by Gordon Dyer on 24 Aug 2003, 4:51 p.m., in response to message #13 by Vassilis Prevelakis You are right. I send my apologies to Dave for mentioning the site, although I do not really understand what the problem is.

Re: Any Interesting HP 3421A applications out there? Message #15 Posted by Ellis Easley on 26 Aug 2003, 4:06 a.m., in response to message #9 by Vieira, Luiz C. (Brazil) My 1986 HP catalog lists an option for the 3421A, "Option 040 Breadboard Assembly [HP44464A] - The breadboard assembly is convenient for constructing custom circuitry. It comes complete with a manual describing the circuit that enables the HP3421A to communicate directly with an 8-bit microprcessor." That manual would probably be quite useful! I wonder if it is on that other website?

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