Recent Posts

1

Beginners / Need help identifying IC of a latched on off module

« Last post by Arek_R on Today at 09:36:17 pm »

Hi all,
I'm looking for simplest compact IC that will switch power on/off via momentary tactile button.
I found this module from ali:

Except the LED and dropper resistor, it's just 4 components + button.
Any ideas what IC is that 6 pin package?

2

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

« Last post by Kleinstein on Today at 09:33:12 pm »

The relevant jitter should be mainly for time intervals of some 1-10 µs. So a little more than just period jitter and still not really long time jitter. It is probably kind of a mix of the short and long pulse lengths in the run-up modulation. The point is how the PWM ratio changes from the nominal.
In the frequency offset plot this would be a frequency offset of some 100 kHz - so not very close in, but also not period jitter.

In most cases the actual oscillator should be less of an issue. A limiting factor could be the actual switch part. Here jitter specs are rare. The more precision type switches are usually slower than typical logic chips and thus more jitter is expected there. I selcted the 74LV4053 not just for low cost, but also for a good speed.

3

Test Equipment / Re: New Hantek DSO2X1X models?

« Last post by DavidAlfa on Today at 09:32:33 pm »

I haven't tried the newer fw yet. Does rolling back to an older version fix it?

4

Projects, Designs, and Technical Stuff / Re: Distance sensor required with 0.1mm accuracy and upto 4m range

« Last post by langwadt on Today at 09:25:42 pm »

https://www.sra-measurement.com/high-accuracy-magnetic-linear-tape

5

Projects, Designs, and Technical Stuff / Re: DIY Digital Caliper

« Last post by MitkoDyakov on Today at 09:20:28 pm »

I was looking at this schema on electronics stack exchange. Which seems to be what I need given the fact that I would power it from 3V



And I build a prototype... a few prototypes



The ones I designed were tragic. I have questions for the design from stack exchange and they are the following:

1. How do I choose values for C1 and C2
2. I understand why R1 and R2 are there, but I don't get why some people choose Mohm values for them but here 10k is fine
3. I did not had MCP6021, but I did had MCP6V11. Is there anything special about MCP6021?

And for people who will ask me about pictures from the scope. The "thing" had nothing resembling the original signal, looks random noise at 1.5V 50mV peak to peak.

6

Metrology / Re: Hioki DM7276-01 Precision DC Voltmeter (9 PPM)

« Last post by Alex Nikitin on Today at 09:16:21 pm »

Here is another measurement result using the DM7275, in this case I was trying to do a 1000:1 transfer of resistance, from Fluke 742A-10K to my 10 Ohm DIY shunt (made using a TO-3 packaged Vishay Foil resistor). The Keithley 263 is used as 1mA current source to supply the Fluke and 10R shunt in series, the voltage on the Fluke was monitored by HP3456A and was stable at 10.00046V (double checked with the Hioki), the Fluke 742A-10K has a measured resistance of 10.00005K so the current was about +41ppm from 1mA. As a control option the ESI SR1010 resistor was used as a 10R shunt in place of my DIY one. Despite some meters of cables and numerous connections, the circuit offset at the shunt was measured below +/- 50nV average, 250nV p-p variations (the Keithley 263 has some useful features to change the current polarity and also switch it on/off so it was easy to measure offsets without disturbing the wires and connectors). The graph below shows two 15min runs with two 10R shunts in this configuration. The temperature variations (measured by Hioki) were below 0.5C). A linear trendline was added to each run to indicate a possible drift in time. Vertical scale is 100nV /div (=10nA/div, or 10ppm of value) , horizontal is samples/time , 1min/div, (=15 samples).

Cheers

Alex

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

« Last post by NNNI on Today at 09:11:54 pm »

I have been reading up on different types of jitter [1], and I was wondering which kind of jitter would have the most effect on the noise/linearity of an integrating ADC, perhaps it is a mix of everything, with each kind of jitter having a certain effect (more noise, worse INL, etc.).

[1]: https://www.sitime.com/support/resource-library/application-notes/an10007-clock-jitter-definitions-and-measurement-methods#Phase-Jitter

8

General Technical Chat / Re: What is this 8-knobbed IBM human interface device in a 1980's Boeing photo?

« Last post by coppice on Today at 09:06:51 pm »

Wacom used to make these back in the day too. We had stylus/pen for it, the digitizer with the crosshair and also a regular mouse which didn't have a ball but an inductive sensor (optical mice weren't invented/common yet).

Wacom came late in the day, and was always focussed on its pen input, with mice and other gadgets being a secondary focus. They never really offered the high resolution of a Summagraphics, but they lead offer wireless handheld devices. That was their big innovation.

How do you figure? The Wacom tablet I bought in the mid-90s had the same 2540lpi resolution of the SummaGraphics, and as far as I know that was in no way new in that generation of Wacom tablets. The manual specifies 0.15mm accuracy with the puck, 0.25mm with the pen.

It might have been just the lack of a puck with fine crosshairs and a lens for the Wacom tablets, but I found them less effective for digitizing. Now you mention it, the actual steps per centimetre must have been competitive, so achieve their smooth fine pen drawing performance.

9

Test Equipment / Re: FNIRSI-1013D "100MHz" tablet oscilloscope

« Last post by Atlan on Today at 09:05:20 pm »

Just in case.  Recently, someone here rewrote the TP configuration.  He had a deposit so he could easily fix it.  Can't upload backup firmware under win?  Apart from the long connection time of 1-2 minutes of the disk it should work.  For example, I didn't back up, I made a backup later.  And that's why I froze the oscilloscope.

10

General Technical Chat / Re: What is this 8-knobbed IBM human interface device in a 1980's Boeing photo?

« Last post by coppice on Today at 09:03:19 pm »

The king of the digitising tablets, Summagraphics, actually became an early king of actual mice. Sun and other workstation makers used their mice. They required a special pad with matrix of lines that was scanned optically by the mouse. Much cruder than today's correlation based optical mouse, but great for their time.

I'd put a huge asterisk after that "great"... they were pretty advanced technologically, but imho were actually a significantly worse experience to use compared to simpler but well built electromechanical ones.

I did have problems with some room lighting. I think reflections from the shiny pad confused the mouse if the angles were just right. When I avoided that situation I was very happy with the Summagraphics mice. I started using them because I was fed up with all the skipping I suffered with mechanical mice.