Author Topic: Affordable Useful AC & DC references  (Read 68271 times)

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Offline bdunham7

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Re: Affordable Useful AC & DC references
« Reply #50 on: April 15, 2024, 06:03:38 pm »
What I mean by that is, if the goddamned thing works well enough to satisfy the target market that it's aimed at, build it and sell it!  Continued attempts at perfecting it will lead to fewer and fewer sales!  |O
If anyone has more suggestions or input, please continue to weigh in with an eye towards what I reiterated above.  :horse: 

First, R&D can and should result in better performance and lower costs.  Both are reasonable goals for improvement.

Second, your concept of 'well enough to satisfy the target market' is a pretty modest goal simply because your target market seems to explicitly be users without the means to critically evaluate the product in any meaningful way.  They're relying on you!

A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline MajorassburnTopic starter

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Re: Affordable Useful AC & DC references
« Reply #51 on: April 15, 2024, 07:18:48 pm »
an island off the coast of a real continent, which island is known to be populated by many of corrupt morals, conversational hyperbole, achievemental dysfunction and an affinity for inbred and, in several cases, immoral so-called "royalty" admiration syndrome.
wtf have I just read.
does it really belong here?
It's all about his attitude toward forum participants. Take some time to read his posts! But, you are right. It doesn't belong here and I deleted it. Maybe you can too.
« Last Edit: April 15, 2024, 07:59:34 pm by Majorassburn »
 

Offline MajorassburnTopic starter

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Re: Affordable Useful AC & DC references
« Reply #52 on: April 15, 2024, 07:34:35 pm »
What I mean by that is, if the goddamned thing works well enough to satisfy the target market that it's aimed at, build it and sell it!  Continued attempts at perfecting it will lead to fewer and fewer sales!  |O
If anyone has more suggestions or input, please continue to weigh in with an eye towards what I reiterated above.  :horse: 

First, R&D can and should result in better performance and lower costs.  Both are reasonable goals for improvement.

Second, your concept of 'well enough to satisfy the target market' is a pretty modest goal simply because your target market seems to explicitly be users without the means to critically evaluate the product in any meaningful way.  They're relying on you!
I don't disagree with your comments at all.

I fully agree that your first comment on R&D and that it should be an ongoing effort. But, marketing a viable product in the meantime should not be prohibited until "all" R&D efforts have been exhausted.

Your second comment is 100% on target! Those buyers would be relying on my integrity and my products to do everything (and more) of what the ads say they will do. That is sacrosanct with me.

However, in the case of these low cost devices, there is no concomitant obligation on my part to educate the buyer as to how, why or where the buyer should go to achieve an even better result than that which the buyer will receive by using my devices.

It's all about value, which includes suitability for the purpose the device is designed for and functionality to provide what the ads claim the device will do. Of course, complete safety is intrinsic and of utmost importance.

The perpetual fault-finding and pursuit of the device's limitations in presenting a low cost device such as mine accomplishes nothing positive for the potential buyer (except not to buy) and nothing positive for folks like me that would like to offer a low cost alternative (albeit with limitations) to that which is already available at much higher cost.

I am not suggesting that product DEFECTS, which prevent the accomplishment of the purpose for which the device is designed, are acceptable in any way.
 

Offline schmitt trigger

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Re: Affordable Useful AC & DC references
« Reply #53 on: April 15, 2024, 10:20:24 pm »
Here's quick drawn schematic of a simple Wein-Bridge 100Hz (Wien or Wein) Oscillator using a simple gain limiting for amplitude stability, followed by 2nd Order Active LPF to reduce harmonic content. Bridge Oscillator should produce a respectable sine-wave output if not forced into excessive limiting, so LPF may not be required.

BOM for just electronic components should be between $0.34 and $1.56, so should suffice as a Cheap Sine-Wave AC source.

Anyway, we haven't built this, someone give it a try and would expect this to outperform the schematic shown earlier. If anyone builds this, please report back results.


Best,

Which opamp part numbers would you suggest to employ? LM358, TL072? Other?
 

Offline mawyatt

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Re: Affordable Useful AC & DC references
« Reply #54 on: April 15, 2024, 11:27:31 pm »
Here's quick drawn schematic of a simple Wein-Bridge 100Hz (Wien or Wein) Oscillator using a simple gain limiting for amplitude stability, followed by 2nd Order Active LPF to reduce harmonic content. Bridge Oscillator should produce a respectable sine-wave output if not forced into excessive limiting, so LPF may not be required.

BOM for just electronic components should be between $0.34 and $1.56, so should suffice as a Cheap Sine-Wave AC source.

Anyway, we haven't built this, someone give it a try and would expect this to outperform the schematic shown earlier. If anyone builds this, please report back results.

Best,

Which opamp part numbers would you suggest to employ? LM358, TL072? Other?

Anything should work, TL is a little better than LM358, both are dirt cheap!! We've just ran a sim (if interested) the 1.5K was changed to 2.2K 2.4K and back to back zeners (in series) seemed to also work a little better than diode bridge and single zener, and 1K changed to 100.

Edit: Actually both the back to back zeners and the bridge diodes with single zener work well in sims, 2.4K and 1K seem to produce a low distortion sine-wave at ~100Hz. Of course these values should be adjusted based upon FFT results to "see" the harmonics, and minimize such!! Note the zener isn't the 1N751A, couldn't find models for these, and we used a OP07 Op-Amp since it's in standard library of LTspice, and didn't want to fiddle around looking for the LM358 model.

Best,
« Last Edit: April 16, 2024, 01:09:11 am by mawyatt »
Curiosity killed the cat, also depleted my wallet!
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Offline thermistor-guy

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Re: Affordable Useful AC & DC references
« Reply #55 on: April 16, 2024, 05:59:45 am »
...
However, after trimming one of the 10V references 2 months ago and keeping it powered on, and after re-checking the SDM3055 vs DMM6500 readings weekly, the 10VDC reference STILL reads exactly 10.0000, spot on, if that's worth anything.
...

That is a good result for a reference in a plastic package, in Florida.

Your wet season is coming up (May-Oct). It would be interesting to check how well the unit performs over the next six months,
with elevated humidity.
 

Offline Kleinstein

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Re: Affordable Useful AC & DC references
« Reply #56 on: April 16, 2024, 10:48:09 am »
The wien bridge oscillator can get a good sine quite well, but the amplitude stability is usually not that great. In the version with just the simple rectifier and zener to reduce the gain the amplitude will not be very stable amplitude. E.g. there are 2 diodes in series to the zener and the capacitor ratio will also effect the needed gain. So I would expect something on the order of -8 mV_pp/K  or close to -0.1%/K for the amplitude stabilty.

There are better ways to stabilize to amplitude, e.g. with an active rectifier or measureing the peak voltage and than actively regulate the oscillator gain. The LPF after the oscillator is only a thing to improve on the harmonics and this is no longer needed with a regulated (e.g. with a JFET) amplitude.
 

Offline mawyatt

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Re: Affordable Useful AC & DC references
« Reply #57 on: April 16, 2024, 01:02:30 pm »
The wien bridge oscillator can get a good sine quite well, but the amplitude stability is usually not that great. In the version with just the simple rectifier and zener to reduce the gain the amplitude will not be very stable amplitude. E.g. there are 2 diodes in series to the zener and the capacitor ratio will also effect the needed gain. So I would expect something on the order of -8 mV_pp/K  or close to -0.1%/K for the amplitude stabilty.

There are better ways to stabilize to amplitude, e.g. with an active rectifier or measureing the peak voltage and than actively regulate the oscillator gain. The LPF after the oscillator is only a thing to improve on the harmonics and this is no longer needed with a regulated (e.g. with a JFET) amplitude.

This was an attempt to keep the parts count/cost same or lower than OP concept utilizing similar cheap components. Of course better amplitude stabilizing techniques are available, but back to back zeners is pretty simple!! BTW if one uses back to back 6.2~6.8 zeners, then TC of the zener is ~ 2mv/K in reverse breakdown and the other zener is in forward conduction is ~ -2mv/K (of course this all varies with current so just a very crude approximation), one might not expect the overall to be as bad as -8 mv/K.

If one is seeking a stable and low TC AC RMS measurement source, the technique mentioned below is hard to beat for simplicity/cost/stability/precision. A couple days ago we were checking our seven 6 1/2 digit DMMs (3-KS34465As, DMM6500, 2-AG/HP34401As & SDM3065X) and quickly verified the AC RMS readings, spot on as usual :-+

https://www.eevblog.com/forum/testgear/ac-rms-dmm-tests/msg3940957/#msg3940957

Edit: Just updated with measurements 4/16/24

Best,
« Last Edit: April 16, 2024, 05:42:44 pm by mawyatt »
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Offline PlainName

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Re: Affordable Useful AC & DC references
« Reply #58 on: April 16, 2024, 01:44:59 pm »
I'm mainly a marketing guy. I realize that engineers and dedicated electronic theoreticians may not appreciate that [...]

Belatedly commenting, although I've been lurking from the start, so not exactly one of those late-coming naysayers :)

As a marketing chap I am surprised you don't see the benefit of having this on a pukka PCB. The first time I saw it in the buy/sell area I just passed straight over on the basis it was an amateur lash-up, and I suspect there will be a number of potential users who have similarly done so. IMO, making it look the part would be a better improvement than improving the specs so far as sales go.

Perhaps the problem is that you're really a marketing guy and don't have the apps, or experience, to create PCBs. If that's the case, the solution may be to ask someone to do them for you. They are not very complex and should be pretty simple to do. If you then order just five, you'll get a professional-looking PCB at less than a dollar, possibly half that if you happen upon a coupon or something. As others have noted, that would improve the reliability in both building and ongoing use, and make it quicker and simpler to assemble. And at similar, or lower, hard cost than the boards you're using.
 
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Offline tatel

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Re: Affordable Useful AC & DC references
« Reply #59 on: April 16, 2024, 01:59:57 pm »
...
I'm mainly a marketing guy. I realize that engineers and dedicated electronic theoreticians may not appreciate that but here's my philosophy regarding my original intent in this thread:

Several people have, belatedly, begun to smell that. It would have helped everybody if you had made that clear earlier.

Quote

What I mean by that is, if the goddamned thing works well enough to satisfy the target market that it's aimed at, build it and sell it! 

A key part of marketing is to give sufficient information to determine what a product won't do.

It would have helped if you did that explicitly, rather than leaving it to people to ask questions and make inferences.

We've all seen claims/patents for better mouse traps and apple corer/peelers. Almost all aren't any such thing.

Ya know, I've never been a fan of your arrogant, self-serving, hyper-critical posts in my own, and several other threads. Guys like you NEVER have anything good to say unless you're touting your own imagined success so, your remarks and criticisms and admitted paranoid suspicions as to where I'm coming from are all wasted hot air on me.

I've noted previously how your baselessly superior attitude tends to embarrass and chase away those participants who you deem to be less learned than you and, therefore, not worthy of your respect to at least be courteous toward their requests for help in some of your replies.

Do me a favor and put me on your ignore list and I'll do the same for you. That way, other participants won't have to witness your desperate attempts to throw a wet blanket on any more of my posts.

EDIT: deleted an asinine reference I made to his homeland. Sorry. Temper got the best of me for a moment.

I found there's quite a few people on this forum that seems to suffer from a mix of Tourette's and Asperger's syndromes. It also seems to me there's a good amount of unused testosterone. And lots of ego. I myself have fallen on that at least once. I have to say, you are just one more cat in that bag, sorry.

But, I have learned, if you post here, better you previously made sure you got a thick enough skin. Particularly if you are asking for advice, more over if you are in some way promoting any product, and still even more if you are asking for free advice to make your product better.

So yeah, tggzzz's comments can be not always the most adequated ones, but at least I have seen him stating he had been made aware he was wrong. That's something I have still not see coming from you. I'm sure you are able to simply state your goals, letting aside any aggresivity, probably originated from any perceived attack to the quality of your product. I for one would greatly appreciate that. Otherwise I'll stick with the people that isn't selling anything. just saying.

And, if there's still some unused testosterone getting the best of you, please go play some union football. Preferably with a "2" on your back. Even in a local league, that will use all of that testosterone, make any skin grow a lot thicker, put any ego exactly where it should be, and vanish any unneeded agresitivity.
 
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Offline MajorassburnTopic starter

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Re: Affordable Useful AC & DC references
« Reply #60 on: April 16, 2024, 02:21:56 pm »
I'm mainly a marketing guy. I realize that engineers and dedicated electronic theoreticians may not appreciate that [...]

Belatedly commenting, although I've been lurking from the start, so not exactly one of those late-coming naysayers :)

As a marketing chap I am surprised you don't see the benefit of having this on a pukka PCB. The first time I saw it in the buy/sell area I just passed straight over on the basis it was an amateur lash-up, and I suspect there will be a number of potential users who have similarly done so. IMO, making it look the part would be a better improvement than improving the specs so far as sales go.

Perhaps the problem is that you're really a marketing guy and don't have the apps, or experience, to create PCBs. If that's the case, the solution may be to ask someone to do them for you. They are not very complex and should be pretty simple to do. If you then order just five, you'll get a professional-looking PCB at less than a dollar, possibly half that if you happen upon a coupon or something. As others have noted, that would improve the reliability in both building and ongoing use, and make it quicker and simpler to assemble. And at similar, or lower, hard cost than the boards you're using.
Thank You and I share your views completely. I have not yet ordered PCB's because the "final" designs for my devices are not yet finalized.  ;)  But, I WILL be using PCB's very soon.
BTW, I have been making (taping, etching, plating, drilling, punching, assembling, blah, blah) PCB's for more than 40 years and I certainly appreciate the requirement that these devices must be offered on professionally assembled PCB's in order to appeal to buyers like you and me.
 

Offline MajorassburnTopic starter

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Re: Affordable Useful AC & DC references
« Reply #61 on: April 16, 2024, 02:25:03 pm »
REPLY TO TATEL:

Thanks for the heads up.  :-+  I didn't quote your epistle because it was so lengthy. But, I hear you and you have offered me some valid criticism. I appreciate that.
Now, I have to go grow another layer of skin, so pardon my temporary absence....  :-DD :-DD :-DD
 

Offline tggzzz

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Re: Affordable Useful AC & DC references
« Reply #62 on: April 16, 2024, 03:18:39 pm »
So yeah, tggzzz's comments can be not always the most adequated ones, but at least I have seen him stating he had been made aware he was wrong. That's something I have still not see coming from you. I'm sure you are able to simply state your goals, letting aside any aggresivity, probably originated from any perceived attack to the quality of your product. I for one would greatly appreciate that. Otherwise I'll stick with the people that isn't selling anything. just saying.

Where I'm not reasonably sure of something, I'll either not comment or I'll add caveats. When I realise I've made a mistake, I don't try to revise history, and I do try to apologise. IMHO constructive conversations cannot occur without that.

I'm very tolerant of beginners asking information, provided they listen to the answers, and think. Watching someone's capabilities improve is a profound pleasure.

We all make mistakes; that's part of learning. However, as I taught my daughter, "let's make new mistakes".

I'm less tolerant of people who don't listen[3], or don't learn, or choose not to improve, or do who misrepresent other people's position[1], or who continue to misrepresent their product[2] (typically to ignorant managers).

I've spent a lifetime being plagued by salesman/companies who make impossible claims for their products. I know others feel the same!


[1] often in the form of chosing to omitting relevant context, or with strawman arguments

[2] e.g. if their product does what they claim, then they've solved the Byzantine General's problem or the split brain problem, or broken the laws of thermodynamics etc.

[3] possibly due to the Dunning-Krueger syndrome
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline Gyro

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Re: Affordable Useful AC & DC references
« Reply #63 on: April 16, 2024, 05:17:34 pm »
...
[3] possibly due to the Dunning-Krueger syndrome

Please stop spouting that bloody stupid term, it encourages copycat use on the forum that takes a while to die down (or at least has in the past). BTW, you spelt Kruger wrong. ;)
« Last Edit: April 16, 2024, 05:39:00 pm by Gyro »
Best Regards, Chris
 

Offline tggzzz

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Re: Affordable Useful AC & DC references
« Reply #64 on: April 16, 2024, 06:32:43 pm »
...
[3] possibly due to the Dunning-Krueger syndrome

Please stop spouting that bloody stupid term, it encourages copycat use on the forum that takes a while to die down (or at least has in the past). BTW, you spelt Kruger wrong. ;)

Looks like I did misspell it, probably not for the first time.

Since it seems you want a discussion (which you think will probably take a time to die down) about the D-K syndrome....

If you have a better shorthand term, let us know. If none, I will continue to use it when I think appropriate.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline Gyro

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Re: Affordable Useful AC & DC references
« Reply #65 on: April 16, 2024, 07:04:07 pm »
About the only thing it means, by current thinking is that people tend to think that they are above average, and possibly that, in their eyes, incompetent people don't know enough to know how incompetent they are. Neither part seems useful in the current circumstances. What about 'competence bias' [Edit, as a less confrontational term].
« Last Edit: April 16, 2024, 07:07:13 pm by Gyro »
Best Regards, Chris
 

Offline tggzzz

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Re: Affordable Useful AC & DC references
« Reply #66 on: April 16, 2024, 07:24:44 pm »
I don't think it means that.

 "Competence bias" is a term that is too ambiguous. Additionally, the pejorative nature of the "D-K syndrome" term is useful in that it encourages critical examination of whether a person is sufficiently knowledgeable to express an opinion/statement.

No, I don't think all opinions are equally valid. (Does any engineer?)[1]
Yes, I do apply that to myself :)

[1] e.g. too many teachers confidently state that, using the normal laws of arithmetic, 1+2*3=9.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline Gyro

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Re: Affordable Useful AC & DC references
« Reply #67 on: April 16, 2024, 07:30:12 pm »
Maybe you're not applying it to yourself quite enough  - Yes, I'm finding you a bit OTT these days too. Possibly a time for quiet reflection.
Best Regards, Chris
 

Offline tggzzz

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Re: Affordable Useful AC & DC references
« Reply #68 on: April 16, 2024, 08:08:27 pm »
You chose to bring the subject up. That ensured it didn't die.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline MajorassburnTopic starter

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Re: Affordable Useful AC & DC references
« Reply #69 on: April 16, 2024, 08:23:43 pm »
So yeah, tggzzz's comments can be not always the most adequated ones, but at least I have seen him stating he had been made aware he was wrong. That's something I have still not see coming from you. I'm sure you are able to simply state your goals, letting aside any aggresivity, probably originated from any perceived attack to the quality of your product. I for one would greatly appreciate that. Otherwise I'll stick with the people that isn't selling anything. just saying.

Where I'm not reasonably sure of something, I'll either not comment or I'll add caveats. When I realise I've made a mistake, I don't try to revise history, and I do try to apologise. IMHO constructive conversations cannot occur without that.

I'm very tolerant of beginners asking information, provided they listen to the answers, and think. Watching someone's capabilities improve is a profound pleasure.

We all make mistakes; that's part of learning. However, as I taught my daughter, "let's make new mistakes".

I'm less tolerant of people who don't listen[3], or don't learn, or choose not to improve, or do who misrepresent other people's position[1], or who continue to misrepresent their product[2] (typically to ignorant managers).

I've spent a lifetime being plagued by salesman/companies who make impossible claims for their products. I know others feel the same!


[1] often in the form of chosing to omitting relevant context, or with strawman arguments

[2] e.g. if their product does what they claim, then they've solved the Byzantine General's problem or the split brain problem, or broken the laws of thermodynamics etc.

[3] possibly due to the Dunning-Krueger syndrome
TO TGGZZZ:  Please either contribute something sane, meaningful, helpful and relevant to this thread discussion or else take your thread-clogging demented crap to some other thread. Thank you.
 

Offline tggzzz

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Re: Affordable Useful AC & DC references
« Reply #70 on: April 16, 2024, 09:06:55 pm »
So yeah, tggzzz's comments can be not always the most adequated ones, but at least I have seen him stating he had been made aware he was wrong. That's something I have still not see coming from you. I'm sure you are able to simply state your goals, letting aside any aggresivity, probably originated from any perceived attack to the quality of your product. I for one would greatly appreciate that. Otherwise I'll stick with the people that isn't selling anything. just saying.

Where I'm not reasonably sure of something, I'll either not comment or I'll add caveats. When I realise I've made a mistake, I don't try to revise history, and I do try to apologise. IMHO constructive conversations cannot occur without that.

I'm very tolerant of beginners asking information, provided they listen to the answers, and think. Watching someone's capabilities improve is a profound pleasure.

We all make mistakes; that's part of learning. However, as I taught my daughter, "let's make new mistakes".

I'm less tolerant of people who don't listen[3], or don't learn, or choose not to improve, or do who misrepresent other people's position[1], or who continue to misrepresent their product[2] (typically to ignorant managers).

I've spent a lifetime being plagued by salesman/companies who make impossible claims for their products. I know others feel the same!


[1] often in the form of chosing to omitting relevant context, or with strawman arguments

[2] e.g. if their product does what they claim, then they've solved the Byzantine General's problem or the split brain problem, or broken the laws of thermodynamics etc.

[3] possibly due to the Dunning-Krueger syndrome
TO TGGZZZ:  Please either contribute something sane, meaningful, helpful and relevant to this thread discussion or else take your thread-clogging demented crap to some other thread. Thank you.

Noted, so even if you "rewrite the history" of your own posts again, the trail won't disappear. For example...

...
EDIT: deleted an asinine reference I made to his homeland. Sorry. Temper got the best of me for a moment.

(Kudos is due for making the change explicit :) )

Hint: your not liking something doesn't make it invalid. The name of Al Gore's movie springs to mind: "An Inconvienient Truth".
« Last Edit: April 16, 2024, 09:14:32 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 


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