Recent Posts

1

Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD

« Last post by KungFuJosh on Today at 01:54:41 pm »

I'm not a somnambulist

Are you sure you haven't sleep walked into a manual or two? 🤣

2

Projects, Designs, and Technical Stuff / Re: digital RGB LED question

« Last post by tooki on Today at 01:52:33 pm »

Ummm… as I understand it (someone please correct me if I’m wrong), square waves are worse for EMI emissions than triangle waves, due to the faster rise times.

It’s still kinda unclear what you are doing. Can’t you share a block diagram or schematic?

3

Dodgy Technology / Re: 10ah 18650 cells

« Last post by Zenith on Today at 01:50:21 pm »

It is a shame that the fake market makes shopping for "real" 18650 cells practically impossible.  The 18650's are so convenient for small flash light and little electronic gadgets that one can cook up.

With the more modern (slim) laptops, they already moved away from using 18650's.  So even the re-packed/re-skined battery market will have a sourcing problem.  I suppose consumer 18650 market is or will be a thing of the past.

In the UK there are several battery suppliers with eshops, which look to sell genuine 18650s and other Li-ion cells by major makers. Prices range from £4 to £8 depending on what you want. They seem to be long term businesses, not fly-by-nights selling a load of rubbish and legging it. There must be similar on-line stores in the USA.

There's a huge market for 18650s for vaping, which doesn't look like disappearing any time soon. Another source of good 18650 cells is your local vape shop, although they'll tend to be a particular type.

4

Repair / Re: Repair tektronix TDS 220 no screen (white screen)

« Last post by rh100605 on Today at 01:48:31 pm »

Hi,
Did you measure all the power supply voltages at the socket on the main board. The specifications for each pin are in the service manual.
If they are not correct then unplug the power connector and measure the outputs of the power supply again.

5

Beginners / Re: LM317 Based Digitally Controlled Power Supply

« Last post by MrAl on Today at 01:41:03 pm »

Thanks all for replying!! I got caught up in my high voltage work and was a little busy with that.

I'm not necessarily opposed to replacing the lm317 with discrete components, I just thought it would be a fun design challenge and a nice way to use the ones I had on hand

I did plan on adding a feedback on the output to the microcontroller (and one across the 1ohm resistor from the current limiter circuit), I just didn't know how to integrate that into a digital schematic.

The main problem that I've noticed based on the replies was the fact that inputing a voltage puts the internal voltage refrence in series, and to be frank I doubt the accuracy of my own voltage input. How would I go about voltage regulation with PWM another way that doesn't have this issue? I couldn't figure it out with my tinkering in simulation software. Can it even be done while maintaining use of the LM317?

Again, I would be perfectly okay with changing out the voltage regulator with discrete circuitry, so long as it's accurate(ish). Thanks!

Well it does make an interesting linear series pass power element as compared to a regular power transistor.

6

Projects, Designs, and Technical Stuff / Re: Small and inexpensive direct thermal printer to print labels

« Last post by tooki on Today at 01:40:56 pm »

I am working on an industrial device that I would like to be able to print out direct thermally printed labels for part identification at the time of manufacture.

I have seen little receipt printers that can be interfaced with Arduino's and such, but wondering if anyone has experience with something that can be used for labels and is relatively easy to interface with and which can be incorporated as part of a larger device (ideally).

I mean something around the size of a pack of cigarettes that I can talk to via serial would be ideal.

You don’t specify what manufacturing volume you’re dealing with, but as a general rule, using el-cheapo borderline-toy products (which is what those Arduino products are) is not something I’d want to risk my production schedules to.

You want a proper label printer. You don’t specify whether you want to simply hide an off-the-shelf printer inside your device (the way that most self-checkout machines actually just use an ordinary, unmodified receipt printer inside, just with the exit slot facing through the cabinet), or truly integrated, like the baggage tag printers on airport self-checkin kiosks, or even one that automatically applies the label to the product. The former is easy, the second a bit tougher because you may face minimum order quantities for bare mechanisms, the third a lot harder.

Many companies sell OEM printer mechanisms; you really should start with a google search for “OEM label printer mechanism”. You’ll be surprised how much you find. Your best bet is probably not to deal with the manufacturer itself, but with one of the many system integrators who specialize in customizing them.

But before you contact them, nail down your requirements:
- print volume (labels per minute/hour for print speed requirements, and labels per month/year for reliability requirements)
- label size(s)
- what is the substrate your labels (or direct printing) will go on?
- label durability (environmental (temp, humidity, sunlight), chemical (solvents/oils/liquids, etc), mechanical (abrasion resistance, adhesion, etc), longevity (does if need to be legible for a year? Five? Thirty?)). This will inform the printing technology you need (thermal, thermal transfer, inkjet labels, inkjet directly onto the item or packaging), the label material (paper, plastic film), lamination, etc.
- with or without liner
- label contents: text, bar codes, images? Black and white, two color, or full color?
- print resolution, depending on your application
- label data variability: does each label’s content vary individually (e.g. for serial numbers) or is it static (e.g. date or lot codes that only vary once per job)? (For truly unchanging data like just model numbers, preprinted stickers would probably be cheaper in the long run.)
- interface requirements: what hardware is driving it, so what hardware interface do you have? Serial (UART, RS232, RS485), industrial bus (MODBUS or whatever), parallel port, USB, Ethernet? And what software will drive it?
- level of automation (from full manual, all the way to automatically applying labels unattended; cut labels? Endless?)
- any applicable regulatory requirements (for example, food packaging has to use food-save inks).
- printer downtime (is production affected by having to take the printer offline to refill, clean, or repair it? Or do you need two for redundancy?)

And that’s just what I can think of off the top of my head. Think about these things so that you can answer whatever questions the integrator asks.

7

Beginners / Re: Calibration - How to Mathematically

« Last post by MrAl on Today at 01:39:08 pm »

Hello again,

Just to note, there are more numerical interpolation methods than there are stars in the sky 

8

Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC

« Last post by iMo on Today at 01:34:35 pm »

@NNNI: I've been interested in a deeper understanding of pros and cons of the rundown+auxADC alchemy as well, therefore my playing with the code and tables..

Your hw is ready for the experiment with that combo, so you may try. I think the key message here is the auxADC is of less "quality" than the rundown process, therefore anything which would "de-load" the auxADC helps. You get rather small voltage at the integrator's output after the rundown, so the auxADC will handle much smaller input voltage range.

My main concern are the various coefficients you have to get somehow and apply "accordingly" to all those elements such you get a result..

But we have here people with hands-on experience, so let us learn from them..

9

General Technical Chat / Re: Why Circuit Breakers DON'T Protect People (electric shocks)

« Last post by tom66 on Today at 01:34:03 pm »

RCDs also prevent fires.  One of the original justifications for RCDs was detecting rodent damage to tasty cables.  A rodent could chew through a cable and create a path from live to earth which might be insufficient to trigger an MCB but the imbalance would quickly trip an RCD.

This is a particular issue in lofts.

https://www.electrical-installation.org/enwiki/Protection_against_fire_due_to_earth_faults

10

Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by RoGeorge on Today at 01:32:10 pm »

This is not a surprise from them, remember the keylogger from Microsoft, in Windows 10?
https://www.pcworld.com/article/423165/how-to-turn-off-windows-10s-keylogger-yes-it-still-has-one.html

It was all official, a keylogger and more (speech input spyware) inside Windows, for telemetry and such, and you were agreeing with that in the EULA.  With reassurements that the collected data is anonymous and for your own good, of course.  So, not for spying, only to give you a "better experience" in the future.