Recent Posts

41

Beginners / Re: Replacing SRAM IC with Flash

« Last post by mariush on Yesterday at 10:05:11 pm »

The SRAM chip  takes the address value from the address pins and reads data from or puts data into the data pins.

the console only manipulates those A0 to A14 signals, so you can manipulate the other address bits.

If A15 is 0, the chip will serve byte range 0 to 32767 
If A15 is 1, the chip will serve byte range  32768 + 0 to 32767

basically formula  is   32768 x A15 +  [ A14 ... A0 = 0..32767]

If you have bigger chips .. byte read/written =  524,288 x A19 + 262,144 x A18 + 131,072 x A17 + 65,536 x A16 +  32,768 x A15 +  [ A14 ... A0 = 0..32,767]  or basically 2¹⁹ x A19 + 2¹⁸ x A18 +  ....

42

RF, Microwave, Ham Radio / MFJ Shutting Down Production and Going Out of Business

« Last post by Sal Ammoniac on Yesterday at 10:03:08 pm »

MFJ, a well-known U.S. maker of ham radio equipment, is stopping production on May 17th and going out of business. They will continue to sell existing inventory after that date and continue to do warranty work, but it looks like this is the end for a company that's been around for half a century.

https://mailchi.mp/62e24f2ccc99/a-heavy-sad-heart

43

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

« Last post by Denge on Yesterday at 09:59:58 pm »

Hello All,

I'm struggling with a new design using the AS6501 chip.  The nasty thing is I don't get an interrupt signal back from the chip after having started the measurement.  I guess there is something wrong with the initial setup of the chip but the longer the more I'm getting lost. 
My goal is to count the time distance between a start pulse on stopA and a stop pulse stopB. 

The setup I use is as follows:
0b10010101       ; 0x95 CFG0: stop A&B active, LVDS disabled, REFCLK active, REFCLK index reset enabled
0b00010101       ; 0x15 CFG1: stop A&B processed, pulse distance, no high resolution
0xC0                  ; CFG2: common & blockwise read
0xA0,0x86,0x01     ; CFG3,CFG4,CFG5 REFCLK_DIVISIONS (100000) for 10MHz refclk
0x00,0x00               ; CFG6,CFG7 LVDS pattern OFF
0xA1,0x13,0x00,0x0A,0xCC,0xCC,0xF1,0x7D   ; CFG8 to CFG15 Fixed values
0x04                  ; CFG16 CMOS level input

At my humble opinion this should be correct for an SPI only communication with this chip.  The results I obtain for both channels (if I skip the interrupt) are for refIndxA and stopA 0x00FFFFFF and for refIndxB and stopB 0x00747474 regardless the pulse distance coming from an AFG.  Anyone an idea what I did wrong here?

44

Beginners / Re: Convert US standard 115V to International 230V

« Last post by radiolistener on Yesterday at 09:59:38 pm »

But if you can't identify and test what those specific conditions are, then the device could never be certified?

Also, it has not been specified that a robotic gait trainer is a safety-critical device. If it stops working for any reason, it is hard to see what harm would come to the person using it.

Undefined/unspecified behavior of device is not acceptable because it is unpredictable and can make harm to the patient. This is uncontrolled potentially life threatening risks for the patient and it's presence shows serious issue in validation/verification process and broken quality management system. 

45

Projects, Designs, and Technical Stuff / Re: How is a motor run capacitor sized?

« Last post by Benta on Yesterday at 09:56:56 pm »

That it's 35 uF is printed on the motor. Period.
That it's 150 V is open to discussion.
It's a non-polarized cap, meaning either paper (no longer common) or poly(xxxxxx) insulation, and for both it's unlikely finding types below 150 V.
33 uF might be easier to find and would work just as well.

BTW, it's NOT a smoothing cap, but there to provide a 90 degrees phase shift for the second motor winding.

46

Manufacturing & Assembly / Re: Vacuum Pick-Up Tool for Rework (Includes video of my own design)

« Last post by thm_w on Yesterday at 09:56:29 pm »

I have tried to search the internet but just found videos how to use the modded aoyue-932, but not any video or web page showing the modded device itself and exact parts needed for the modification. I do not know anything about solenoid valve pumps, never used one. I assume that it would need to be something called "2 way 3 position valve"? But even from those there are multiple control voltage options, sizes and whether to have normally open or normally closed one. So some help and pictures would really be appreciated :-)

If you watch Steves video it looks like he used a "VT307-5D1-01F-Q". 3-port 24V solenoid:
"Series VT 3port, direct operated poppet valves are compact in size, yet provide large flow capacity, and low power consumption. The series is suitable for use in vacuum applications. The VT valve is a single valve with 6 functions (universal porting type) such as N.C. valve, N.O. valve, divider valve, selector valve, etc. The manifold style valve, series VO, can be easily converted from N.C. (normally closed) to N.O. (normally open) by merely turning over the switch cover."

I used a 3/2-way Normally Open (NO) or Normally Closed (NC) (3-ports 2-positions) 12V vacuum rated poppet valve, which cost $8.

Voltage depends on what you want to use for a control voltage.
Then make sure you can get fittings for the hole sizes it uses to connect to your tubing.

47

Programming / Re: Linux Dependency Black Hole

« Last post by tatel on Yesterday at 09:55:51 pm »

I'm not a ham, either.

It seems there's at least one hackRf related package official in debian, with command-line tools. I'm sure you could do your developments using pure FOSS tools, but you probably are used to some different thing? That would be understandable.

It there could also be some tool to convert packages from one distro to another, but IIRC, "alien" works the other way: RedHat->Debian

Ataradov said the software you are looking to use is for Ubuntu 20-22, and out of that, you are on your own. I think he's right. So, having Ubuntu installed (brrllrrll) would be the easier way. Short of that, it will probablybe  easier get it working under Debian that under Fedora.

Good luck

48

RF, Microwave, Ham Radio / Re: Fly swatter ham radio transmitter

« Last post by joeqsmith on Yesterday at 09:55:33 pm »

Using a car ignition coil to power the latest transmitter.  Using my new Tecsun PL-990 portable receiver to determine how far we are transmitting.   Also shown is a demonstration of the home made cohere.   



Old movie showing using an X-ray machine as a transmitter to signal for help.  In the movies, it messes with every radio broadcast.  It's Hollywood.. 

49

Beginners / Analog Multiplexer-Demultiplexer Switch Vs Input Voltage

« Last post by 2X on Yesterday at 09:55:07 pm »

Hello,
I saw at the datasheet of the 74HCT4052 Multiplexer-Demultiplexer two parameters that seems similar to me but have different values. The parameters are the VI (input voltage) and the VSW (switch voltage). Why the range of the VI voltage isn't between VCC-VEE like VSW voltage? As I understand this analog Multiplexer can have on his selected input a signal/voltage between VCC-VEE and if the output will enabled the input will pass on the output (little smaller because of the RdsON of the switch) or am I wrong?


Page 6
https://assets.nexperia.com/documents/data-sheet/74HC_HCT4052.pdf

50

Test Equipment / Re: SDS800X HD Bug Reports + Firmware

« Last post by 2N3055 on Yesterday at 09:50:04 pm »

I can confirm this one. It applies to Qualified and Delay triggers; seems to work OK with other trigger modes.

Will check .. Thanks.

Thanks for looking into this.

Looking back over the past few days, it seems like Qualified and Delay trigger are problematic in multiple ways: Bug entries #14 to #16 refer to them, now this new "trigger threshold in zoom mode" issue; they also both have a less-than-obvious UI and very sparse documentation in the manual.

I noticed that the SDS2000X+ manual does not mention them, so these two trigger types were probably added later and have not seen as much field testing as the rest of the firmware? I realize that it's probably very late in the game for the firmware update currently in the works, but if there's still a chance to overhaul Qualified and Delay triggers, that would make them a stronger part of the offering.

Come to think of it -- it seems that the Nth Edge and Setup/Hold triggers are also later additions which were not in the original 2000X+. Maybe they deserve some extra scrutiny too? I'll try to find some time tomorrow.

Like I said, new FW is coming. That is all I can share.