Recent Posts

1

Test Equipment / Re: SDS800X HD Wanted Features

« Last post by RAPo on Today at 11:58:03 am »

I use the scope with a web interface, and hardly use this physical button, so if I can control it via the web interface I am happy, otherwise I would be highly dissatisfied

There could be some space be freed in the screen. Its not jut the "Meas" button. The hardware buttons work very good!

2

Thermal Imaging / Re: Help with "80 series Thermal imager" by insight vision services

« Last post by Niall135 on Today at 11:57:13 am »

Thank you Fraser and Bill for all the help and advice on this series 80, but i have had no luck recomissioning the power supply.
The 12 battery input bypassing the 240v transforer did not help as the output voltages were still missing.
Replaced 2 suspect mosfets to no avail, i think power distribution pcb with the focus pots etc has succumbed to age (i know what that feels like). 
I should have taken Frasers sage advice ad not spent so much time and effort on it.
But all is not lost. I have TIC fever now and got my wife to buy me a DH-BF5421-T for my birthday. It came with a blackbody and 2 tripods.
My plan is to install the microbolometer in the series 80 body where i can utilise the large 35mm f.07 lens and the focusing servo.
So far so good as im getting great images in preliminary tests.  I just have to fabricate a carriage to get the sensor centralised. Ill post on this seperatly.
But this means all the boards from the series 80 are available for spares along with the pevicon tube. First refusal to Fraser and Bill. DM me if they are of interest.

3

Microcontrollers / Re: How do you search for a microcontroller ?

« Last post by artag on Today at 11:54:10 am »

There are an impossibly large number to select from. As Smokey implies, the learning curve for an unfamiliar one can be brutal - ST are particularly complicated to set up and their Cube system to help generates code that many people despise.

If you have any existing systems, use a top-end device within that (eg Teensy within the arduino ecosystem) to produce a POC at low cost in terms of learning effort, and look out for problem areas such as cost, speed etc. You might prototype on teensy and then go to  an FPGA with embedded processor once you have a good idea of your needs.

Don't commit to a device you have no experience of and have to spend 6 months learning before you can be productive, only  to find there's some new requirement, constraint, or bottleneck that forces you to change.
 

4

Test Equipment / Re: Siglent SDS800X HD - Using SCPI with python via telnet to measure with 2 gates

« Last post by eTobey on Today at 11:52:41 am »

sending multiple commands, so the speed of 2 times per second is okay, you can executing the script When sleep.   

I could not... As it is only 2 meters away from my bed, it its pretty loud and uses a lot of power. It should be able to do more than 2 times per second for this powerconsumption.

5

Microcontrollers / Re: Routines to convert binary to BCD in C code

« Last post by Picuino on Today at 11:49:49 am »

Performing the binary-to-decimal conversion with custom routines has helped me to be able to dump huge numbers (48 bits long) from the counter of an 8-bit microcontroller that counted 10MHz pulses for long periods of time and dumped the count by UART every second.

6

Test Equipment / Re: Hacking the Rigol DHO800/900 Scope

« Last post by Mechatrommer on Today at 11:46:52 am »

All this separate work really needs a github repo to track. If not for direct use for the recompilation of the .apk, then at least as a source to make diffs against and patch your own decompiled .apks.

imho step by step guide how to hex-edit/patch and which part is what, is what i more need.. and then others can continue the work on other parts and produce step by step again, until majority of parts are hacked or known. or a readable script or table in file (byte position, byte value to patch)... so end users also can freely customize which part he/she prefer to change which part to stay default. ymmv.

7

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

« Last post by artag on Today at 11:40:02 am »

I believe the brother label printers (usually USB, thermal, a wide variety of cheap clone labels available) are supported by drivers within the CUPS printer control system in Linux.

Receipt printers intended for integration in POS terminals used to be primarily from Epson and had parallel or serial interfaces. These may be more suitable if you have a simpler embedded system and don't want to run Linux - though it has many advantages such as easy ability to support remote login, web control pages etc. If the core functions are very simple it might be sensible to implement those on a microcontroller and then put peripheral functions such as web control and printing on a small embedded linux board that isn't essential for basic operation.

8

Test Equipment / Re: SDS800X HD Wanted Features

« Last post by eTobey on Today at 11:40:00 am »

I just realized, that there are buttons, that have a function that i often use, but do not use the button itself for.

How many of you acually use this button probably with only a mouse?

There could be some space be freed in the screen. Its not jut the "Meas" button. The hardware buttons work very good!

If actually some others use these buttons it is also a possibility to have a menu butto, that combines a few of the menu buttons. Its quite a waste of space, if a button occupies a part of the screen, when it has only 3 entrys, which sometimes are not used at all.

9

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

« Last post by Mechatrommer on Today at 11:38:48 am »

1) to be precise, anything more or equal to Sample rate / 2 will not be reconstructed correctly, i havent found literature saying exactly 2.5

Anything equal to sample rate/2 can NOT be reconstructed.

thank you for re-emphasizing my statement and hence Nyquist Theorem.

Now work from there to something a tiny bit below that ... you'll go between zero crossings and peaks over time, and get an AM effect as seen in that video.
...
2.5 isn't a mathematically derived number, it's what works in practice.

yes 2.5 is not derived from theory, its probably from empirical testing of imperfect sampling mechanism (presence of jitter/harmonics/hi-freq more than nyquist limit)...

10

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

« Last post by armandine2 on Today at 11:35:56 am »

I am trying to understand the sizing of a run capacitor

  I assume it is a run capacitor that delivers a smooth flow of power to the motor,

I am not clear why this is 35uF and why it is 150V.  Can someone help me understand how these values are determined?

Thanks!

.... not sure this is going to help - or is wholly or vaguely correct  - but here goes something to ponder:

single phase with no phase shift means you don't get a rotating flux - it just pulses and you have no torque on to the rotor.

introducing an auxiliary winding, which is phase shifted up to 90 degrees using a capacitor will get you the rotating flux.

the primary winding on a phasor diagram is heading northeast and with an LCR meter you could plot that - and determine the capacitor value to shift the phase to the auxiliary winding 90 degrees. The resultant ideally heading off to the East.

I got this half remembered from Slemon -
https://www.amazon.co.uk/Electric-Machines-Gordon-R-Slemon/dp/0201077302