Recent Posts

31

Projects, Designs, and Technical Stuff / Corrosion on DIP pins

« Last post by Alex Eisenhut on Today at 04:37:52 pm »

So I retrieved my PET 4032 from my parent's house. The 4032 is a 40 year old computer. It was in the basement for 30ish years. There was no flooding.
How do some chips have rusty pins but the next one over doesn't?

Those are RAM chips, but various 74LS also have the same rusty pins while the next one doesn't.
And the rusty/non-rusty RAMs are within one bank of 8 chips, so the difference can't be that one was wave soldered and the other by hand.

That rust means the end of that chip as the corrosion will crack open the two halves of the body and let humidity in the guts, right?

32

Test Equipment / Re: New 2ch pocket DSO+SG - Zeeweii DSO2512G

« Last post by chemary on Today at 04:36:57 pm »

That's OK, just don't overdo the calibration, it won't be like a multimeter.

For calibration, I need a more or less accurate laboratory power supply and a functional signal generator, which I don’t have.

If you don't want to spend much, I purchased a cheap device like this one https://www.aliexpress.com/item/1005006786894152.html it comes with a hand written paper with the real measured values with good equipment and also states the date and temperature when they were done, it can be used to know how good are the measures of your equipment.

33

Test Equipment / Re: New 2ch pocket DSO+SG - Zeeweii DSO2512G

« Last post by Aldo22 on Today at 04:32:14 pm »

For calibration, I need a more or less accurate laboratory power supply and a functional signal generator, which I don’t have.

It's not really necessary.
You have "Auto cal" in the Aux menu.

34

Metrology / Re: ESI RV622A Resistor Repair

« Last post by gmilliorn on Today at 04:31:59 pm »

Reviews of those cheap spot welders aren't very encouraging, and require an expensive LiFePo battery
or such.  The lead wires are about 1mm thich at least.

However, while searching, I found this comment from Earle Rich which discusses making just these
types of resistors:

https://hackaday.com/2021/06/16/review-battery-spot-welders-why-you-should-buy-a-proper-spot-welder/#comment-6357273

A bit too vague to replicate, though.

35

Beginners / Photodiode output emulation

« Last post by elki on Today at 04:26:47 pm »

Does anyone know if there is a simple RC circuit that could emulate the current output of a photodiode? I wonder if it is possible to achieve starting from a function generator, pass it through an RC circuit, and then using the obtained current pulse as input to a transimpedance amplifier. Any suggestions are appreciated.

36

Repair / Re: SDG830 another boot issue

« Last post by sgeets on Today at 04:19:37 pm »

At one point it didn't look good to get this unit recovered.  But I didn't give up. With the help of tautech, it was finally recovered and upgraded to the latest firmware.  Another device saved from the bin.  Many thanks to tautech. 

37

Beginners / Re: uCurrent Gold Schematic

« Last post by xvr on Today at 04:16:20 pm »

Strange arrangement of C6/R12/R16 and C8/R13/R17 - they short circuited.
OP circuit also wrong - they plugged without any feedback circuits.
I also would some protection for input circuit, for example - diode (or TVS) across J1. If CPU turn on wrong shunt resistor on high current it will just blow out.
Q1 placed upside down.

May be something more, that I didn't spot [yet].

38

Microcontrollers / Re: Has anyone used ASAN & MSAN, and relevance to embedded arm32

« Last post by ataradov on Today at 04:06:07 pm »

I don't think those would be very useful on embedded code. Asan adds instrumentation in the code and then replaces low level malloc() and free() calls with custom tracing versions.

This typically increases code size by 2-3 times, decreases execution speed by the same 2-3 times. And it also needs a lot more RAM to store all those allocation records. On embedded with custom allocators, you will essentially get one or no real malloc() calls, so the tool will be useless.

In theory, it might be possible to work with the instrumented code and match it with the custom allocators, but I'm not aware of anyone doing it.

39

Beginners / Re: uCurrent Gold Schematic

« Last post by uf29857 on Today at 04:05:30 pm »

Thanks for the feedback. Will the circuit work as intended?

40

Other Equipment & Products / Re: Any opinions on the Aixun T420D?

« Last post by Astray on Today at 04:02:53 pm »

Yes, T115A handle with modified plug (with added "stanby" pin #4 and wire soldered to it) is connected directly to the host. Other end of the added wire must be connected to mast with bracket for T115A handle.
Yellow pair must be disconnected from mast's nut because this pair is "standby" pin signal of cradle's plug that also connected with T245/210 bracket and work with other channel (T245A handle in my case).
Sorry for my English, I can't explain it in any more detail or more clearly. 
....
There is another way to get "donor's" pin without buying donor handle or plug. You can extract pin #3 (extractor) from plug of holder. But in this case you have to connect extractor in parallel with bracket so that the station goes into standby when you change the 245/210 tip.
But buying a donor T245 handle is more reasonable, since this handle does not lose its functionality after removing the unused pin #6 and can be useful at any time if the genuine AiXun T245A handle breaks.

Do you have a photo or diagram of how the wire to the tall stand is connected to the main station? Is that standby pin just a ground pin or something different?

Wondering if might not be possible to internally connect the standby pins of both channels inside the main station so there's no need to run an extra wire.

Does anyone else know how these soldering stations work to put irons into sleep mode?

T420 in the T245A configuration (with T245A handle included, but without specific mast with hangle bracket for T115A handle) have a regular price for $181.48 at this store. I used a $20 coupon at "anniversary sale". But similar coupones or promocodes you can get it very often. Aliexpress holds different sales almost every month.

The T115A handle i bought at the China DIYPHONE Store aslo with coins. Regular price was $8.19.

Additional cheapest T245 handle I bought for $3.03 with coins just to have a "donor's pin".

Your prices are just across the board cheaper than mine, I believe it has to do with location as they probably have shipping costs included in the total price of the device. I shopped around quite a bit to find the cheapest I could and $210 was the cheapest before any coupons.

In hindsight, the cheapest maneuver was probably buying a T405 unit and hoping to get sent one with T420D firmware and buy the 245 handle. I think this would be the most cost effective as I've seen the 405 go for $170 before coupons and it would also include the little arm stand and you wouldn't need to buy those separately. Still a gamble though because no way to know if you'll get a main unit with T420D firmware.