Recent Posts

21

Other Equipment & Products / Re: Pace ADS200 soldering station

« Last post by bdunham7 on Today at 04:24:22 am »

The Pace ADS200 has a handy led on the front of the station to show when it's heating and is more accurate than most youtubers.

It also has a handy display that shows how much the temperature drops under heavy demand, although that doesn't include thermal resistance between the thermocouple and the tip surface.  It's good that they are transparent about showing that drop, but it would be better if they improved on that.  It seems that they have and now we all want to know how--and if we can get the improved product somehow.  If they could get the maximum short-term average power up 20%, that would be a big deal IMO.

22

General Technical Chat / Re: Do you think an LED is a resistor?

« Last post by TopQuark on Today at 04:23:48 am »

The terms resistor or diode are just words we humans coined to describe certain electrical devices with a specific electrical property, to help us engineers abstractly express how our circuit design works and it's expected behavior.

There's no reason why you couldn't call every 2-leaded device as a resistor:

- A diode is a non-linear resistor that conducts current exponentially with applied voltage, and only in one way
- A capacitor is a giga-ohm resistor with two electrodes that conducts through dielectric materials, it also happen to store charge too. 
- An inductor is a low-value resistor made with coils of copper wire wrapped around something, that also happens to store energy in the magnetic field.

Go ahead, replace all your schematic symbols with resistors.

If a p-n junction can be described as an resistor, they why not draw your pnp junction transistor as a few resistors too?

Go ahead, when your boss or client asks you to design a circuit, send them a page of resistors. Next time you buy a CPU for a PC, ask for a package of 1 billion integrated non-linear resistors too! See what you get.

The fundamental reason a resistor is a resistor, and a diode is not a resistor, is because we engineers decided it is just easier for everyone to agree on using terms to abstractly describe devices with different classes of expected behavior.

It is non productive to call everything "resistor, but non-linear", "resistor, but stores charge", "resistor, but inductive". We decided there's a line in the sand where we split all these "resistors" into different abstract things, giving them different names "diode", "capacitor", "inductor" while reserving "resistor" for the linear device we already understand it to be.

You can invent your own method of describing a circuit. You can invent your own mathematical system. You can invent your new language. We simply agreed on what we commonly use to get everyone on the same page, and not having to explain everything from scratch every single time.

23

General Technical Chat / Re: Do you think an LED is a resistor?

« Last post by MK14 on Today at 04:17:20 am »

This is a set of...
of...



...nonlinear resistors!
Yeahhhhh!

Now take this big huge set of nonlinear resistors, and put it near the set of linear resistors (they also have their own symbol).
What have you got now? What is the set formed by the set of linear and nonlinear resistors?
It's a set of...
...


Resistors!
Yeahhhh!

I hoped (it was somewhat intentional on my part), that my recent post(s) in this thread, would elisit, more information from you (the OP), as to what you thought was going on, and it seems to have worked, as you seemed to have done that.

In summary and as a sort of analogy, this is how I seem to understand, the point(s)/concept(s) you seem to be trying to portray.

(Hypothetically speaking, i.e. I have NOT just done this).
I create an interesting and long new thread on here, describing my new $50,000 electric car, which happens to have (very approximately), a 100 volt battery set up, along with a 100kW motor (engine if you like).  I have then described the technical details, of all its (interesting to some) systems and functionalities.

You have now jumped into my (hypothetical) thread, and said ...
"no no NO NOOOOOOO!!!!, what nonsense MK14 is talking ......"

This is all really a 1 milliohm resistor (non-linear resistor), with a supplied link to a set theory YouTube video, for very young people.

So, although there is a little bit of technical merit (correctness), and the $50,000 new car, is a bit like (sort of, at a stretch of the imagination), a 1 milliohm resistor (non-linear).

The vast bulk of the time, and to almost everyone, it is NOT a useful, interesting or good way of expressing, what it is.

E.g. Which thread title would people be more likely to click on?

"I just bought my great new, $50,000 super fast electric car, technical details of all its electronic systems included, with advanced AI self-driving to level 3"

Or

"Today I bought a 1 milliohm, (non-linear) resistor"?
The start of the thread then says...
100V 100kW (max)


I hope my analogy is accurate?

24

Metrology / 5.5D vintage Systron Donner 7205 DMM with 0.5% FS error

« Last post by trobbins on Today at 04:15:51 am »

I am trying to clarify why i get a 0.5% low FS displayed measurement in a vintage Systron Donner 7205 DMM.  This DMM has a front-end analog section which appears to be fine, as it sends an accurate 1V FS signal for voltage, current and resistance processed levels onto a subsequent analog section that prepares signals for a final dual-slope integration based measurement/display digital section that uses a Fairchild 3814 IC.

The relevant schematics of the front end sections are on pages 83-4 (of 89) of the manual at https://www.dalmura.com.au/static/Systron-Donner%207205%205.5%20Digit%20Digital%20Multimeter.pdf, and the digital section schematic is on p.80.

Before starting a FS cal check, I was able to confirm ok levels for shorted inputs on all ranges, and confirmed supply rails are ok, and exercised the range selection switches (with judiciously applied contact cleaner spray where appropriate), to remove the typical switch contact related gremlins, as well as removing the BCD option board (which was a contributor to noisy readings). 

During FS cal checking, the front end switching and dc zeroing circuitry on p.83 generates a 1V FS level at the 'Amp Out' TP1 node, and I have confirmed that for voltage, current and resistance references of various decades applied to the DMM inputs, I do get an accurate and processed 1.0000 Vdc level being passed on to the next section (p.84 of that doc). 

But that is where my understanding of the analog and subsequent digital processing circuitry functions stop as to identifying why and where there may be a 0.5% low FS error subsequently coming in.  I have confirmed the +10Vref  and -10Vref levels generated on the p.84 schematic are acceptable (error and balance within 2mV). 

I'd appreciate any guidance on what to assess on the p.84 analog circuitry, as I haven't yet got the scope out to confirm digital control lines are appropriately applying the +10 and -10V refs and the zeroing, or the operation of the integrator and zero detector analog circuitry, prior to being passed to the digital board.

Ciao, Tim

25

Repair / Re: Motherboard has no power - Clevo W650SC

« Last post by amyk on Today at 04:11:11 am »

Current-limited power supply and a thermal camera.

26

General Technical Chat / Re: Do you think an LED is a resistor?

« Last post by Kim Christensen on Today at 04:08:24 am »

Ok, it really is basic comprehension of inclusion.

Yea, and you fail it badly! 

And now, I'm going to "unsubscribe" to this thread, and leave you to your "own devices".

27

Other Equipment & Products / Re: Pace ADS200 soldering station

« Last post by Shock on Today at 04:06:52 am »

Steve's videos should not be considered scientific results. The coin test in part compares the regulation of a station. Which ever station overshoots the most during thermal recovery will get the best result, in fact it's possible to beat the Metcal this way.

The video did highlight that the Pace station showed 122.9W peak during heat up and 114.9W peak power during the coin test. The type of test, equipment and measurement technique were not ideal. The Pace ADS200 has a handy led on the front of the station to show when it's heating and is more accurate than most youtubers.

Which reminds me there was a video I saw today showing a JBC heat up in a few seconds. The guy started counting from when the temp showed on the display (already past melt point). By that logic you don't even need to turn them on.

The JBC early tip life failure won't go away because of words alone. You can reduce it by good cleaning habits and by limiting your alloy and flux choice, avoid contamination and boards originally soldered with chinesium. It's "safer" though to pay attention in Steve's video and buy a Metcal if you can afford the TCO and want the best coin test performance money can buy.

But if you are after the most pointless performance due to the JBC overshooting higher than "most" Metcal set temp tips. When you do a prolonged test over many minutes the JBC starts to average ahead. So Steve's been lying to us all along.

28

Projects, Designs, and Technical Stuff / Re: USB C routing: Will this work?

« Last post by hermitengineer on Today at 04:06:27 am »

You are correct that this is a 2-layer board.  The ground pour on the bottom is as complete as it can be and does have connection between parts, but it is partitioned by bottom layer vertical tracks.

If I have a need for high or super speed, I'll keep grounding and impedance in mind though.

29

General Technical Chat / Re: A serious (as in not troll) requestfor help w/ultrasonic transducer

« Last post by floobydust on Today at 03:59:07 am »

I'll be happy if you find something that can extend the life of these machines. I just want success for people's endeavors here, nothing owed lol.

Engineering used to be about problem solving, figuring it out. Like doing a crossword puzzle. You never worried, just kept chipping away and learning. Some searching, the right keywords and I can somewhat understand the machine enough to help a bit. Physics, MecE, EE (multidiscipline) knowledge needed for this Tempo make it difficult.

Today, young engineers literally have a panic attack if they don't know something. There seems to be a stigma with "not knowing", even in business and management. I find it funny, being free of such worry. Electronics gives a constant humiliation for those types of people, the "know it all" types especially.
If you don't know enough, then ask - I've learned to reach out to manufacturers and sometimes they have great expertise.

30

Repair / Desoldering advice

« Last post by antenna on Today at 03:57:41 am »

I recently took on a repair and I am dealing with solder I have never encountered.  It is a scooter that quit working, error code states low motor voltage, even though the battery is good and fully charged.  I removed the controller, the mosfets appear fine, so I suspect the relay contacts.  Unfortunately, the solder that was used barely melts at the max setting on my soldering iron (480°C) and there are surface mount components including electrolytics all around the relay and underneath it.  To make things worse, the relay is soldered into plated vias.  So far, I have used an entire stick of ChipQuik with a solder sucker and managed to get the coil leads free and most of the solder off the contact legs, but I struggle getting the solder inside the vias to come out or even melt.  The relay won't budge.  I plan to keep going with the chipquik alloy, but I wonder how many rounds of getting them hot it can handle before I destroy other things.  Does anyone have advice for a situation like this?  I would try hot air, but there are SMD electrolytic caps and other chips right next to the relay and I fear hitting it that hard will do damage to them as well.

edit: another concern I have is whether or not the chipquik is getting in the via and that the relay is simply glued down, but given how many rounds of chipquik it took to get the bulk of the solder off the legs would suggest its just that high of MP.  I want to try to get under the relay and pry, but there are SMD resistors under it and I don't know what might peel off with the glue that may be there.  They built this thing to not be repaired.  I am tempted to decap the relay to check the contacts and cut it out if bad.

Any suggestions would be appreciated, thanks!