Recent Posts

11

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".

12

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.

13

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.

14

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.

15

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!

16

Test Equipment / Re: Used spectrum analyzer buyer's guide

« Last post by usagi on Today at 03:54:50 am »

Anritsu MS8609A Product Page



Thread: Anritsu MS8609A 9kHz - 13.2GHz Spectrum/Signal Analyzer - Short Review

quite a few of these are on ebay now (2024-04-23)

17

Projects, Designs, and Technical Stuff / Re: What FCC certification test that I need to pass for project that I am working on

« Last post by Smokey on Today at 03:50:40 am »

Ha!  I just saw that it looks like you posted the same thing to as many sub-reddits as you could think of. 

18

Projects, Designs, and Technical Stuff / Re: Voltage regulators - die pictures

« Last post by Noopy on Today at 03:47:40 am »

The µA79MG corresponds functionally to the µA78MG, but regulates a negative voltage. The output voltage can be set between -2.2 and -30V. The Power Mini Dip package was available in three versions: T-1, T-2 and T-3. The µA78MG documented here uses the T-2 variant, which has a angled metal tab on each side. The µA79MG shown here uses the T-3 variant, which only has one straight metal tab. In the T-1 variant, two metal tabs are bent downwards so that they can be soldered to the circuit board.






The dimensions of the die are 1,9mm x 2,0mm.




Several masks are depicted on the right edge. In the lower area there is a character string which is presumably 79MGZ.




The datasheet shows the typical circuit of a 79xx voltage regulator. The operation of the circuit is described with the Mikroelektronika Botevgrad 7915 (https://www.richis-lab.de/voltageregulator20.htm). The µA79MG differs from this only in minor details.




The circuit on the die corresponds to the illustration in the circuit diagram. A series of resistors are integrated in the right-hand area, which can be used to represent a fixed-voltage regulator. To the left of these resistors is an unused capacitor, which probably stabilises the feedback loop.

The capacitor C2 appears to be divided into two areas. The n-doped buried collector is used, which represents the desired capacitance with the p-doped substrate.




A transistor and a few resistors are integrated in the bottom left corner of the µA79MG, which have no effect on the circuit. The Fairchild Voltage Regulator Handbook from 1978 contains the circuit diagram of the µA79M00 fixed-voltage version. There, the additional components are used to represent a different tapping of the reference voltage for the higher output voltages. The higher reference voltage ensures that the feedback voltage divider does not reach too extreme resistances at high output voltages, which worsens the control behaviour. In order to be able to display the full output voltage range with the µA79MG, the low reference voltage must be selected.




There are two discolourations in the power transistor which indicate that the voltage regulator was defective.


https://www.richis-lab.de/voltageregulator28.htm

 

19

Projects, Designs, and Technical Stuff / Re: Coulomb counter IC for coin cell products.

« Last post by ArdWar on Today at 03:46:44 am »

Just go up and down on TI's parametric table. You'll eventually find one in DSBGA/WCSLP package if you really need miniaturization.

20

Projects, Designs, and Technical Stuff / Re: What FCC certification test that I need to pass for project that I am working on

« Last post by Smokey on Today at 03:46:35 am »

Nice looking product.  Did you have that case custom made?

Based on this random guy on the internet:
https://www.freepower.io/blog/the-challenges-of-designing-a-free-position-multi-device-system

... wireless chargers are considered to be "intentional radiators" by the FCC, so you will need Part15 ClassC certs.

Every device is different but for reference, I did a BLE wearable last year.  I passed on the first round and it ended up taking 2 days of test time and costing about $6200.  Failing would have required a redesign and retest at about the same cost.

I'm no expert, but if you are starting from scratch it's a pretty steep learning curve.  You can do some pre-compliance testing in-house but it requires some decent gear to have any real confidence in the measurements.  I was sort of surprised there weren't more companies offering pre-compliance services.  Hopefully you are in an area with at least some test labs locally.