project: extending HP3478A functionality

[yo0]

thank you, now i understand. i was believing was hardware related as i read in fluke 8060a manual.

The fluke 8060a manual says that the base specifications for dB modes are the same as DC Volts/AC Volts.
So I assume it's just a math function.
What are you going to use the dB measurements for?

thank you! audio level adjustments in tape recorders mainly


best regards.

Pio

[coromonadalix]

@yoO

You can do your math

0db is 775 mili volts  etc ... you have charts floating on the web ??

[yo0]

Thank you, Yes I know, just was a suggestion of features.

[Miti]

great project!, it is possible/viable  add dB measurements, frequency, and remember  the prefered digits  for example 4 1/2? thats will be great!, by the way  there is any source to buy for the project pcbs already populated like drop in solution? @Miti?

best regards.
Pio

Sorry, I missed your question. No, I don't have fully populated boards, only bare boards.

[yo0]

great project!, it is possible/viable  add dB measurements, frequency, and remember  the prefered digits  for example 4 1/2? thats will be great!, by the way  there is any source to buy for the project pcbs already populated like drop in solution? @Miti?

best regards.
Pio

Sorry, I missed your question. No, I don't have fully populated boards, only bare boards.

thank you very much, do you think can be a business oportunity for you to sell it like a finished product?  do you think there is enough demand? i think still are thousands 3478a working out there.

if not, do yo have the needed files and the bom to replicate the pcb for sale or share?, i mean for my personal use.

best regards.

Pio

[Miti]

thank you very much, do you think can be a business oportunity for you to sell it like a finished product?  do you think there is enough demand? i think still are thousands 3478a working out there.

First of all this is Kirill's project so he should be the one to commercialise it, if he decides to. He must have put much more hours in the SW than I've put in the PCB.
Second, no, I don't see a significant commercial value in this project, designed for a dying multimeter. It is very useful, nice exercise for hobbyists though.
I'm sorry Kirill, I hope you're not offended by what I said. 

Edit: I can sell you a board or two if you want. Contact me on the PM if you want.

[yo0]

thank you very much, do you think can be a business oportunity for you to sell it like a finished product?  do you think there is enough demand? i think still are thousands 3478a working out there.

First of all this is Kirill's project so he should be the one to commercialise it, if he decides to. He must have put much more hours in the SW than I've put in the PCB.
Second, no, I don't see a significant commercial value in this project, designed for a dying multimeter. It is very useful, nice exercise for hobbyists though.
I'm sorry Kirill, I hope you're not offended by what I said. 

Edit: I can sell you a board or two if you want. Contact me on the PM if you want.

Thank for your valuable response, you're right, my apologies.

Best regards.

Pio.

[kirill_ka]

Why apologise? I agree with Miti. I don't think enough items would be sold to justify the effort. Pio, just get the board and build it!
All the parts are easily available and cheap. In fact, I was able to find everything at home. By the way, I highly recommend PC-speaker style buzzer,
as I find variable tone continuity test to be very useful.

[kirill_ka]

Release 1.4 is ready.
* 5 presets can be saved and loaded. Preset 0 used after power-on (power-on SRQ should be enabled).
* Added menu timeout.
* Fixed key handling in MINMAX mode.
* Added error reporting. If something wrong happened, the error code is displayed.

There's a hidden feature. If an "ext" function used within 5 seconds before entering the menu, that function would be saved in preset.

I didn't have time to test it much as usual (this is the major advantage of non-commercial project by the way  ).

[Miti]

Hi Kirill,

What compiler do you use?  Can it be compiled with AVR Studo? Can you post the hex and eep as you did before?

Thanks!

[kirill_ka]

Hi Kirill,

What compiler do you use?  Can it be compiled with AVR Studo? Can you post the hex and eep as you did before?

Thanks!

I thought I did upload the binaries 
Now it's there.
https://github.com/KIrill-ka/hp3478ext/releases/download/r1.4/hp3478ext-1.4.zip

The compiler is avr-gcc. Windows package is called winavr. And yes,  it comes with AVR Studio.

[Miti]

Kirill,

Most of the externally driven buzzers are single tone, usually the sound intensity decreases significantly outside of the resonant frequency they were designed for. Did you experiment with multiple buzzers, do you have a part number to recommend?

[kirill_ka]

Kirill,

Most of the externally driven buzzers are single tone, usually the sound intensity decreases significantly outside of the resonant frequency they were designed for. Did you experiment with multiple buzzers, do you have a part number to recommend?

I salvaged it from a PC motherboard. The part number is AC-1205G.
The datasheet shows a pronounced resonance @ 2kHz. In practice that AC-1205G sounds ok and I don't feel like it needs a freq response compensation.
https://www.eevblog.com/forum/projects/project-extending-hp3478a-functionality/msg2251509/#msg2251509

[kirill_ka]

Here's the settings I use for now:

Code: [Select]

<GPIB> Ocont_ran
1    # 300 Ohm range
<GPIB> Ocont_beep_ta
5    # 0.5 Ohm resistance for beep_pa & beep_da
<GPIB> Ocont_beep_pa
2000  # 8kHz
<GPIB> Ocont_beep_pb
40000 # 400Hz
<GPIB> Ocont_beep_da
15    # 15/256*100% = ~6% duty cycle
<GPIB> Ocont_beep_db
15
<GPIB> Ocont_beep_tb
1000   # 100 Ohm resistance for beep_pb & beep_db
<GPIB> Ocont_thr
1000   # 100 Ohm threshold where it starts buzzing
<GPIB>
I just noticed a bug in handling cont_thr parameter. There's an integer overflow so it triggers at lower value than specified. I'll publish a fix for it soon.

[kirill_ka]

I just noticed a bug in handling cont_thr parameter. There's an integer overflow so it triggers at lower value than specified. I'll publish a fix for it soon.

https://github.com/KIrill-ka/hp3478ext/releases/tag/r1.4.1

I spent some time trying to trace out a rare glitch where wrong data was received from GPIB.
It appeared due to the extension board had a bad contact with the socket. So I soldered contacts from 2mm pitch pin header on the top of the contacts I used previously. Note that I have an older model HP3478A which has a special socket and requires narrow contacts.

[Miti]

Hi Kirill,

Any chance you can include Prologix commands into your project?

[url=https://www.eevblog.com/forum/projects/ar488-arduino-based-gpib-adapter/]https://www.eevblog.com/forum/projects/ar488-arduino-based-gpib-adapter/[/url]

Into your project? I doubt it would fit but I thought I’d ask anyway.

Edit: I remembered this has been discussed.   

[kirill_ka]

Hi Miti,

I think I will do. It should be quite easy, but I need to find some time.
Do you mean some particular application? I want to start with some minimal implementation.

[Miti]

No, I don’t have a special application. The other day I turned on one of my two meters just to be greeted with “Uncalibrated”, after I just replaced the batteries in the spring. I measured the battery and it was at 22mV. I measured the good one and it was 3.6V so basically right where I left it in March. I went to buy a new battery and out of four that I measured, one was dead, one was at 3.4V, so it was discharging internally, the other two were around 3.67V. You can’t trust anything anymore, bad quality everywhere.
Luckily, I saved the calibration memory before replacing the batteries so I thought, how nice would be just to connect the USB cable and upload the constants back using lmester’s free control program, since the extension is there anyway and it has GPIB capabilities.
I’m just trying to be greedy at your expense. 
BTW, I tried your new version with variable tone. I assembled two new boards for that, I didn’t want to jinx the existing ones by replacing the internally driven buzzers, just in case I didn’t like it.
It’s really good, not too much variation in the buzzer level as I expected. However, I have a suggestion, you know by now that I always have one to the desperation of another member  here .
Most of the time I use the continuity function to check for, well, continuity and that high pitch is bothersome. Can you separate this function in two? Make one “CONT” with a fixed frequency like before, and the other one “SHORT DET” or “CONT VAR” for short detection.
One more thing, the beep in autohold is a bit too long for me and compared to Fluke.
I like the latch though.

Again, great project, thanks for the effort Kirill. This is my go to meter for almost everything after I added your extension and my backlight.

[kirill_ka]

No, I don’t have a special application. The other day I turned on one of my two meters just to be greeted with “Uncalibrated”, after I just replaced the batteries in the spring. I measured the battery and it was at 22mV. I measured the good one and it was 3.6V so basically right where I left it in March. I went to buy a new battery and out of four that I measured, one was dead, one was at 3.4V, so it was discharging internally, the other two were around 3.67V. You can’t trust anything anymore, bad quality everywhere.

I still haven't replaced the battery. My 3478 dated back something like 1984 and the battery is from 1994. Calibration RAM data is kept in a safe place though.

Luckily, I saved the calibration memory before replacing the batteries so I thought, how nice would be just to connect the USB cable and upload the constants back using lmester’s free control program, since the extension is there anyway and it has GPIB capabilities.

It can be done with 3478ext in current state. I write my "remote controlling" scripts in Tcl. However, I agree it's much easier to do with a dedicated program.

I’m just trying to be greedy at your expense. 

Another approach would be to send the 3478ext to lmester to encourage him to support the command set of 3478ext 

BTW, I tried your new version with variable tone. I assembled two new boards for that, I didn’t want to jinx the existing ones by replacing the internally driven buzzers, just in case I didn’t like it.
It’s really good, not too much variation in the buzzer level as I expected. However, I have a suggestion, you know by now that I always have one to the desperation of another member  here .
Most of the time I use the continuity function to check for, well, continuity and that high pitch is bothersome. Can you separate this function in two? Make one “CONT” with a fixed frequency like before, and the other one “SHORT DET” or “CONT VAR” for short detection.

For now you can save 2 presets with different settings for the CONT mode. Is it ok for you?

One more thing, the beep in autohold is a bit too long for me and compared to Fluke.
I like the latch though.

It's configurable. Try "Ocont_latch" to see the current setting. Ok, got it. I didn't care to tweak it. What's you suggestion?

Thank you for the feedback

[Miti]

Another approach would be to send the 3478ext to lmester to encourage him to support the command set of 3478ext 

I guess I could do that, lmester was very open with supporting Galvant interface. I have options though so it is not a priority. Ver. 6 of Galvant (released by steve1515) works well with lmester program, I have an Agilent PCI GPIB and I hope I'll get a NI USBGPIB soon, so no worries.

For now you can save 2 presets with different settings for the CONT mode. Is it ok for you?

I forgot about the presets, I haven't tested them yet. More button presses but I guess that should work, let me give it a try. I should save the default that loads at power up with constant tone and another one with variable tone.

It's configurable. Try "Ocont_latch" to see the current setting. Ok, got it. I didn't care to tweak it. What's you suggestion?

Fluke only beeps for about 25-30ms. I guess somewhere in the range of 25-50ms should be ok.

One more feature of Fluke meters praised in one of the threads on this forum is beep on diodes. I've tested my fluke 179 and it beeps about the same 25-30ms between  100-840mV of voltage drop. Below 100mV is continuous beep indicating a short, above 840mV is nothing.

[Miti]

I was trying to save two presets, one with fixed pitch for continuity test, and one with variable pitch for short detection. It looks like they are using the same EEPROM addresses as the settings overwrite each other.

[yo0]

i have a new arduino nano v3 clone collecting dust, it can be used for this project in a basic implementation form instead the pro mini + UART to USB adapter combo? i have a gpib connector too, my idea is using the arduino externally in a suited enclosure for it and hopefully a funtional buzzer , i think this way i will lost the conectivity (powered via usb) but i am more interested in the new dmm features.  i am new in arduino stuff. any help or advice will be really appreciated.

best regards.


Pio

[Miti]

I guess that would work but, unless you install two GPIB connectors, in and out, you loose the GPIB interface. The good thing about the internal implementation is that it is completely transparent to the GPIB communication.

[yo0]

I guess that would work but, unless you install two GPIB connectors, in and out, you loose the GPIB interface. The good thing about the internal implementation is that it is completely transparent to the GPIB communication.

thank you, you are right about that issue, i have really not use of the gpib communication. i was thinking the nano can be powered via some of its pins leaving the usb port free, maybe the unused usb port can be used for comms, i really don´t know. 

anyway this exercise hopefully can be another implementation option for the users less skilled like me.


best regards

Pio

[kirill_ka]

I was trying to save two presets, one with fixed pitch for continuity test, and one with variable pitch for short detection. It looks like they are using the same EEPROM addresses as the settings overwrite each other.

Hi Miti, it seems that I was not getting notifications for some reason. So I missed this. I'll take a look at this later.

Finally I got around to adding support for Prologix commands.
At least it works with the https://www.eevblog.com/forum/testgear/free-hp3478a-multimeter-control-program/

Link to the new release at github:
https://github.com/KIrill-ka/hp3478ext/releases/tag/r2.0