Recent Posts

1

Power/Renewable Energy/EV's / Re: DIY Battery Bank from Recycled 18650

« Last post by nctnico on Today at 07:24:47 am »

Someone on facebook is selling these:

I attempted to let the seller know this is a dangerous build, but they don't seem to care.

I thought it would be worth while getting opinions (technical and rational) from the community so they can see that it's not just me being annoying.

What are your thoughts on using random batteries that are soldered together in this way?

Fantastic, if you want set your home on fire. This is wrong on so many levels. It basically goes against all good practises where it comes to building Li-ion battery packs. The fuses will not help against the number one issue: when a Li-ion cells goes off, the thermal runaway will ignite the surrounding cells.

2

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by shapirus on Today at 07:20:28 am »

Rigol can go to 100MHz (or 125MHz) but is severely limited by its sampling rate.

Incorrect.

It can be unlocked to 250 MHz, which is actually ~290 MHz (-3 dB), and it has no aliasing issues at that frequency in single-channel mode (1.25 GSa/s).

With two channels operating (625 MSa/s), aliasing starts to become noticeable only after 230 MHz, but it remains still usable at 250 MHz.

The 100-125 MHz upper usable limit is only relevant when 3 or 4 channels are enabled (312.5 MSa/s sampling rate).

3

Test Equipment / Re: SDS800X HD Wanted Features

« Last post by eTobey on Today at 07:17:25 am »

Feature suggestion:
When choosing max frames for sequence, and changing the timebase, the lowest frames that were possible on the timebase persists, even when timebase changed back.

Suggested behaviour:
A number that has been entered or when choosed max, should always be set if possible. Maybe have 2 fields that says "frames set up" and "current frames" (max frames that can be setup) in the menu.

4

Other Equipment & Products / Re: Three most useful tools I got from AliExpress

« Last post by pope on Today at 07:03:08 am »

Links to the tools please. 

The board holder does look very nice, and do I see you invested in a chip tester? The one Adrian Black (digital basement) used to test al kinds of chips with?

I really like the board holder.    If a board is too long, you can always hold it sideways or buy an Aluminum bar at a metals supplier.

Yes, I am assembling the retrochip tester from 8bit-museum.de.  I found it is much cheaper (but more painful) to order the parts from DigiKey; $120 vs about $250.

Per Request:

https://www.aliexpress.us/item/3256806317632603.html

https://www.aliexpress.us/item/2255800993178532.html

I have to find the ProsKit desolder gun.  But it was about $100; bought it as a "first timer" on another account.  (Yes, I am that cheap!)

Did you buy the board holder from this specific shop? IT has rather low feedback so I'm a bit hesitant.

5

Test Equipment / Re: Cheap oscilloscope for checking mains power quality? Also logging equipment.

« Last post by csuhi17 on Today at 07:02:25 am »

The oscilloscope can only be used for one phase, you will not be able to use Pass/Fail for several phases at the same time. It can only be set to one channel.
It is worth using a differential measuring probe to monitor the voltage, you will need a current measuring probe to measure the current.
The battery does not last long, a few hours max.

I found three options when I did this myself.

1. You buy a power meter with a bluetooth connection, which you can connect to an Android device and use it to log in at some level.

2. buy two Bluetooth multimeters and/or lock pickers, one for current, the other for voltage, which you also connect to a phone, if you're lucky, you can set the logging interval in its software.

3. buy a cheaper energy quality meter.

3.1 I found one that can be connected directly, but it has an RS485 connection, I didn't check what it can do.
I couldn't find much information about it.

3.1 There is the ME435 Meter, which is an independent item, for approx.: 400-500 USD. ETCR4320, ETCR4300 that I still found.

3.2 borrow one for that little time. If you need to use it a lot, it is cheaper to buy one, if you only need it now, then borrow one.

The scope has a high sampling rate, you can slow it down, but then you need one with a lot of memory, otherwise you won't be able to set it properly. And it's even more expensive because of the extra accessories.

The consumption meters are cheaper, but the sampling is slower, which I use 1 sample per second.

The multimeter is a little faster, 3 samples/second, and you can use it for other things later.

If everything is true, the ME435 works with 8000 samples/second.

For me, the end result was the Atorch AT4PB consumption meter, connected to the Unihertz Tank phone, very long operating time. Only the bluetooth version. In any case, not the TUYA and similar WiFi nonsense...
And two Owon CM2100B.
For these, there is still work to be done to evaluate the result.

The Schneider PM5110 mentioned by Adam4521 is 64 samples per second if I see correctly.

6

Beginners / Re: How Current Limitation is happening in the circuit???

« Last post by Xena E on Today at 07:01:42 am »

It is not an auxiliary coil that is used for deriving 5V for volt amp meter.


From the main transformer after full wave rectification,  I have used it.

 

No, you haven't. Not connected like that, its a dead short.

If you want help, please provide detailed photographs of your work so far. If you are a student, a tutor would throw out what you have provided so far as being inadequate.

I want to derive variable power supply up to 30V and current limiting adjustable up to 5 amp.

The regulator chip you are using is ubiquitous, why not just copy an application note from one of the manufacturers?

I repeat, if you want help post photos and details.

Regards,
Xena.

7

Projects, Designs, and Technical Stuff / Re: No interrupt from AS6501...

« Last post by Denge on Today at 06:56:47 am »

Hi Dieter,

I did download it too. But I'm programming in assembler...
I'll try to compile it too in the hope I succeed :-)

Greetings

8

Projects, Designs, and Technical Stuff / Re: Opamps - Die pictures

« Last post by iMo on Today at 06:56:03 am »

What I saw with my first 1050 (the one with the ext. clock input and built in caps) how easy it died. I operated it in my null meter (2x4.5Volt) and suddenly it got hot and died. It ended up in the trash can (so no sample for Noopy, a pity).

9

Test Equipment / Re: Troubles with HP-8903B

« Last post by DeepLink on Today at 06:49:03 am »

I have several 8903B's and the internal oscillator is ~OK
Remember that you only have 5 digits on the frequency counter

Well, I did design a PLL to lock my 8903 to my house reference (10MHz)
Now the 8903 frequency counter is spot on, as it is directly linked to the reference
But the 8903 generator, is not locked to the internal oscillator, so it will never be precise (it is steered by the internal oscillator)
Not that it is needed for such an instrument

In loop back mode - you should see distortion below -90dB (0,003%) (look in the manual for how to perform the test)
I had one of mine down to -98dB (0,0012%)
I prefer dB for such low levels of distortion
You mention 150mA - but I guess you mean 150mV
Try to increase the output to 6V, 1kHz - then you should see distortion below -80dB (0,01%) if worse, then you instrument is faulty

Also the optional filters is not the best "quality"
So I did my own design with modern components and got the THD better
The filters is also hard to find these days

Also tried to improve the output generator / input circuit with modern Op-Amps and reducing noise in the supply's
Got some marginal gains
HP did make a pretty good Audio Analyzer, and it is my preferred analyzer.
It has "instant on" and is pretty simple to use, high voltage input and good bandwidth (I've measured them to more 500kHz)
If I need better performance I do have some modern FFT analyzers, but they all lack the above features

/Hans

10

Microcontrollers / Re: DS3231 RTC module huge drift

« Last post by retiredfeline on Today at 06:44:55 am »

There is no point trying to save battery by powering it with the main supply, the coin cell lasts a long time already. I have a couple of modules that have been running for a couple of years continuously. Some designs have a couple of diodes for dual supply if you are that fussy.

As I said, the I2C pins can be pulled up by the main supply, they are open drain so won't affect the RTC timekeeping.