Видео

Thanks! I haven't looked at the application for some time, so I'm not sure how much I'd need to do for it to become generally useful. Sounds like the graphing aspect interests you, but that was a separate app from the GPIB scripting/logging app, and I'm fuzzy on how easy it was to use them together. I'd like to make then available, but would want to first do some work on fixing bugs and polishing it up a bit. But you've prompted me to give it some attention sooner than I might have done otherwise. If/when I make it available, I'll make some sort of video to introduce it...

Thanks for replying. Yes, it's a shame RUclips likes to play funny buggers with these stats and biased promotion. I'm starting to think shorts are not worth it to me, unless the message is very simple. It was hard to cut my original recording down to less than a minute without losing part of the message. The portrait format is another difficulty. I think I'll just change the linked video to public, and forget about shorts for now!

@@bertoid I prefer your more detailed repair/teardown content, cheers.

Thank-you for your encouragement, and for your detailed comment. I hadn't considered (or wasn't aware) of many of the points you raise. They explain most of my confusion about view counts and subscribers, so thanks for making it clearer. I knew there had to be issues like those that I was simply not aware of, and it was only in connection with the 1000+ milestone that made me think it even worth mentioning. The main trigger for the video was my second question about the short not seeming to link to the unlisted longer video. I just find it hard to believe that not even one out of hundreds of viewers had clicked the link. Maybe some answers on that will be forthcoming... Thanks again!

@@bertoid hi, i had seen your first short a while ago, but to be honest, i have missed the extra link below. Also when i open one of my favorite RUclips channels (like yours), i always view them from pc and click on the tab video's to watch there latest video's, so more then once i have missed the shorts of my favorite channels. Think this is the case with many people. grtz

Yes, I didn't notice the links on shorts for a long time myself (they are too similar to the title I think). Which I tried to fix by adding text about the it in the video. Also, links in shorts is a more recent development, so maybe many people don't know to look for it.

Yes, but allow for higher leakage, and if a problem is indicated, you'd have to check them individually to find which is bad. And of course, they should be the same voltage rating (or only test to the lowest value)

@@bertoid 👍thank you for the reply

Thanks! I'm not 100% sure what you mean, but assuming you want the measurements I made, I've uploaded the test runs data to:- uploadnow.io/f/fbbC10b It's a RAR archive with 8 test run files in CSV format, each with done with a different load. So the max currents (at 240V) in each file vary from 265mA to 6.7A. The format of the data is:- HPV - Voltage measured by the HP3456A PZV - Voltage measured by the PZEM-004T HPI - Current calculated by the HP3456A from the voltage across the shunt resistor PZI - Current measured by the PZEM-004T with 5 turns through the current transformer (so 5 times the HPCurrent) BUT! I'm not happy with the data at low currents. I should have used a much higher shunt resistance so that the voltage developed across it at low currents is above the noise floor. The data files could all be joined together, sorted (and smoothed) to get the full range with many more data points. Hope that helps...

Early 70's (1971) Its a Schlumberger VB6601 Voltmeter, and still very accurate. I did a teardown of it 5 years ago:- ruclips.net/video/19-QcH3rS7s/видео.html

Thanks! I haven't done much with it since the video. The Positive Tempco of light-bulbs, makes this load unsuited to regulated power supplies - they can go into wild oscillation. But it's fine for say, the raw or rectified output of a transformer. I have some projects like that where this load will be useful.

Glad you liked!

Thank-you!

20 second search on google:- www.manualslib.com/manual/3373996/Data-Precision-1350.html#product-1350

@@bertoid muito obrigado, já me inscrevi no seu canal Abraços e sucesso

It's not really a protection circuit, as it's operated manually. Just a switch and a large resistor. The circuit is powered via the resistor at startup, and seeing a normal current draw on the meter (meaning it's oscillating, and not just one FET stuck on), I flick the switch to provide full power without the resistor.

@@bertoid thanks

Thanks, I'm glad you enjoyed it!

I like the alligator clip idea. There's also fairly small EZ hooks. While trying to find what those EZ hooks are called, I found this:- www.jaycar.com.au/10-piece-jumper-lead-set-alligator-clip-to-pin/p/WC6032?pos=2&queryId=c29805d4b387867ffa7d6b5941eb3854&sort=relevance&searchText=alligator Perfect!

Groan....!

Obrigado, que bom que você gostou!

Commiserations over losing your system like that. I should be right for caps, but thanks anyway! I'll get back to working on these machines one of these days...

Didn't I? Yes, almost certainly it is OK. But with 2 chips, and 1 meter - doesn't matter which is in it, so I didn't bother I suppose.

I Hope you do enjoy it! All of the recent improvements were made by my long time collaborator, Jim. He has also created lots of documentation which is in the GitHub release.

Melbourne...

@@bertoid We are based in Sydney at the @australiancomputermuseum - great work on restoring these units. We have a few dozen PDP 11 variants for restoration

@@digitalrampage Hi, I may have seen those units (Max showed me around the old warehouse many years ago). If I was in Sydney, you probably would have seen quite a bit of me by now! And since the 04 and 34 don't work, I would like to have tried some board swapping with your units - would have been very helpful in isolating the faults...

Are you saying that this circuit can work with 360 volts?

Thanks, glad you enjoyed it! Yes, the toggle switches and lights are cute - at first, but then it quickly becomes a pain. So it's only done to get a bootloader program into memory, that can then load in much bigger programs from mass storage. Having core memory, the bootloader is still there when the power goes off, so would not be a problem with this unit. And later machines with volatile MOS memory usually include a board with the bootloader program in a small read-only memory.

Thanks! I'm very happy with my old boat anchors. I like the LED displays - none of that VFD rubbish! And you'll have very high confidence in your 3457's measurements with those 2 extra digits to check it against!

Maybe it'll never do anything ever again, but if I can fix it, I should be able to run some very simple programs. Mainly though, these things are just for historical interest...

These computers have a lot of historical significance. The PDP3 was built for the CIA to model the physics of the SR-71 spy plane. The PDP7 was where Unix was built and first officially ran on one of these computers. It lives on today. Unix powers MacOS, iOS, Playstation, and Linux was based on it and powers 95% of the web. Over 40% of hospitals in the US ran these to scale patient data past hand written and copied everything. The PDP11/03 was the first computer to use integrated circuits.

Yes, I would like to sell them. And I'd like to get a reasonable amount, though at the moment I'm not sure what they are worth. I need to do some research into that. Are you in Australia? Would you want the whole case, or just the board? (much cheaper to ship if overseas) You can reply here, or email me: intabits@gmail.com (especially if you have an offer that I couldn't refuse!) PS: I just saw that you are in Tassie (I only saw b6700 at first)

Thanks! I'd like to get them all working, but without working systems to swap boards with, it's going to be a battle. Previous fooling about has shown me what a rabbit hole these can be, taking months out of my time for a small result. (and much worse if you try to make videos of it). Before going there, I want to make a logic analyzer, and study the CPU operation in great detail to come up with a plan of attack.

I don't know about that, but I doubt it. Would be nice if it was, and fun to try making it work. But for that we'd also need details on how the sound was generated. My guess is some sort of basic Digital to Analog Converter, connected to some conveniently accessible internal register. If the program and details was available, I think the simulator could be bodged to make it work...

LOL!. But actually I'm more the "Transformer" guy, I just haven't shown the worst of it yet...

I'm not sure about that. The newest version (see more recent video), which was improved totally by my main collaborator (I did nothing). I think he said it is actually faster than the real machine, but don't quote me on that....

Thanks! Yes, I normally do set the meter to 100PLC to get more stable readings when I'm trying to get the most accuracy - I don't know why I didn't do that here... As for Triax, I want to see where I can get to without it, before climbing down into that expensive rabbit hole! As you suggest, guarding, shielding and grounding all need looking at. But for me, this was a nice first cut, and there's lots of scope for further experimentation and development of an improved version.

I've got a big UPS with dead batteries. I was thinking the most salvageable parts would be MOSFETs and the like, never thought about it possibly having a nice boofy transformer! I must take a closer look at it...

No, I haven't tried that. I can only assume that it would really mess things up, maybe even damage the controller chip. Remember that the burden resistor is only half an Ohm, so the voltage across it is tiny - only 6mV with 2.5A current flowing. The diodes would add 600mv to that...

Sorry I can't. I did not reverse engineer this thing. It's just a piece of interesting junk that I opened up...

That's an interesting method, though I wonder if many circumstances could use it. Presumably the external supply would in most cases operate from the mains, which could just be used directly. It would be a strange setup where there was a power supply, but no mains to drive it. Battery backup maybe? (sort of a UPS for the PZEM) Depending on circumstances, the PZEM might still need a modification to separate its supply input from its measuring input. Something to keep in mind though...

@@bertoid , the measuring input works fine when using a external powersupply, the problem of no screen below 80V is due the "capacitor dropper" circuit not delivering enough juice to power the meter. With a external supply connected in parallel over the big capacitor, the meters shows 0V when no voltage source is connected to the input. Like i mentioned before, you need to add a diode, to prevent backfeeding into the external powersupply. Also due the capacitor dropper circuit is not isolated from the mains, the external powersupply now also become hot (live), so this external powersupply can't not be used for anything else in the same projectbox. Instead of using a mains powered external powersupply, you can also use a battery pack, so that the meter becomes portable. Grtz.

Yes, even staying with 8N1 format, there's baud rates, DTE vs DCE, crossover cables, hardware & software flow control, etc. If it works, great. Otherwise it can take a while to work out what's not been set right.

Good points. Playing with such sensitive circuitry is pretty new to me, so I expect to learn a lot about noise and shielding...

Using 2 in parallel for 5 is a good idea, and reduces the parts BOM. But I'd use TH parts for their power rating, and there's room for them. I take your point about getting spot on (that's what substitution boxes are all about). But these switches are too crappy for even 1R minimum, so I'd still shift everything up by two decades.