Recent Posts

Pages: [1] 2 3 4 5 6 ... 10 Next
1
Building SMT in two passes on the same side with a reflow in between isn't really a thing done at any serious level. As you note, getting paste on is a problem and also a pick & place has no concept of avoiding collision with already placed parts.
Mini rework stencils and templates are a thing, but they are not the solution for you, you could try fiddling with syringes but its much harder than you might think, and might not work at QFN scale such as that PD chip. ?You choices include:

Change your design so that it more closely fits JLC parts library surely they have a USB PD chip in there somewhere.
Carry on as you are.
Sub contract the assembly to someone in the UK who sources all the parts for you  - someone like @Jackster or.. me (other choices exist). This frees up your time for testing and validation & revisions instead of fiddly rework level assembly.
Find that PD chip as a pre assembled module - it probably exists.
You can play with small placers, but this is something you should only do because you really want to get into that side of things and at some level want that toy. Feeders are the most expensive part of an SMT setup, most places will have spent considerably more money on their feeder stock than the placer itself. In small volumes you will frequently find yourself supplied with parts that a pick 'n place can't handle without a custom tray or some chip straightening or other process first.
2
Yes indeed, your phase noise is better.

I am fairly certain that my measurements on the SVA1032X are not unique to my device because I have read some other reports on the internet (and of course EEVBlog) that the phase noise is not that good over the entire spectrum for this series.

Now you have an SSA3021X+ and I'm not sure if it has the same hardware as an SVA1032X.

Bad phase noise is usually caused by the loop filters in the PLL's. It may be that Siglent has already made improvements to the SSA series.
3
Test Equipment / Re: SDS800X HD Bugs/Wanted Features
« Last post by tszaboo on Today at 08:48:22 am »
Save button does nothing in the Bode plot, it should make the usual screenshot.
Which file format and to Internal or USB ?
Same settings as regular save. Png, external if available.
4
Repair / Re: SIP compressor won't start?
« Last post by artv on Today at 08:43:51 am »
There is a suspicious mark by the overload switch. Speaking of overload switches, I had one fail on a cheap compressor - it's worth checking if yours is working properly (Attachment Link)
Yes the thermal switch did fail a while back and was replaced. This one is working though - I've getting 240V into the compressor. Thanks though.

Open its output to the atmosphere so that you're not feeling the force of compression, and see if it's still difficult to turn. I recommend checking the cylinders for roughness.
I'm not quite sure what you mean here? Thanks.

Is the motor stiff when you try to turn it with no load attached? There could be an obstruction or the bearings have had it. The bearings should be standard parts.

Do the windings smell and look burned?

If it's the windings, a look on the web shows new compressors are about £500 and replacement motors are £300. There are rewinding services up and down the country, or maybe you could rewind it yourself.

I don't think it's definitely the case that the windings are the problem and there are a lot of other possibilities to check out. It could be something basic like corroded contacts.
Thanks - do you mean extract the motor? I've not looked how easy it is to get to it. It won't be worth spending more than £50 on it.

Is the pressure relief valve stuck shut?

Is the start capacitor centrifugal switch stuck open?

Start capacitor, (the big value one!) Going short under load?

Valves stuck in the head?

Is the auto full pressure switch stuck open? (Unlikely)

Most of the above usually caused by disuse. Generic faults but I've no experience of that particular model.
Thanks - not exactly sure how to check some of those things but will take a look.
5
I found a partial match - Mestek DM100C.
Full manual range
Backlight always on
But there's auto power off :(
And I found a Mestek DM100 for myself not too long ago. It's not the same as the DM100C:D
Full manual range very very fast - about 7-8 measurements per second!
Backlight always on
But there's auto power off  - I don't consider this a disadvantage as there is an option to disable this option.
Here are some videos I made to compare the measurement speed on different models of multimeters.
https://drive.google.com/file/d/1m60CEWaHaikNET9LHQe4FNIQ2wMML--F/view?usp=sharing
https://drive.google.com/file/d/1YDuHIkqz_OJWkojXECs_tUfaNv5TNv8e/view?usp=sharing
https://drive.google.com/file/d/1ycFufU5mmWupxmZT1Vg-ODec9VoSV0R5/view?usp=sharing
6
Microcontrollers / CH32V003 Flash like Eprom
« Last post by Atlan on Today at 08:41:06 am »
HI. is there any way to ensure that the data in the flash is not overwritten during programming.

I use cast flash as eprom. Everything works, but every time I program the data is deleted. Is there going to be some kind of protection to prevent it from being deleted? or if I put them on the bootloader address, won't they be deleted there? is such a use possible? I assume that uP does not contain a bootloader? well thank you
7
When I choose a bit of phosphor screen I view the same strange. Not all time but very often.
FW 1.2.9

Jitter would look similar, difficult to see in your jpg. If you use the original bmp-file of the zt-703 screen-copy function and convert it directly to png for uploading here would show your curve more detailed...
I hope, Zoyi also implements in future firmware saving directly to png instead of bmp, would be possible to save 10x more screencopies in the limited memory of the zt-703. One guy in the dt-830 forum already asked for implementing that, beside some more functions ...
8
Projects, Designs, and Technical Stuff / Re: Impedance of a plasma arc
« Last post by Marco on Today at 08:39:39 am »
From Google :
https://www.researchgate.net/profile/Abdel-Aleam-Mohamed-2/publication/224074690_Direct_current_glow_discharges_in_atmospheric_air/links/55dda7e308ae591b309b7360/Direct-current-glow-discharges-in-atmospheric-air.pdf

According to that, if you current limit at 5ma to keep it not immediately lethal it's about 400kOhm per cm.

A welding arc is a lot lower, it will also blind you and throw a lot of ozone and molten electrode around.
9
Beginners / Pulse stretch and delay
« Last post by elki on Today at 08:32:47 am »
Hello! I am having a hard time understanding why this simple circuit based on 74HC123 does not work in practice, while the simulation results are as expected. I am getting exactly the same stretched pulse, but somehow, I am not succeeding in introducing a delay. Any ideas? Maybe there are some practical considerations to take into account?
10
Test Equipment / Re: Anritsu MT8801A/B/C & MT8802A
« Last post by smdbg on Today at 08:32:41 am »
MT8801B - 2 in 1  software - GSM or IS136 - select in menu,  image  HxD and vhd. + files . all from 1999. if somebody have newer versions (updates) - please share.

revision: Main 3.02 , GSM 3.03 , IS136 3.05 , ROM 1.05
options 01.02.04.07

https://drive.google.com/drive/folders/1uJGasdO4S3EL8RJCf4LQ26yPg4o9utJ6?usp=drive_link
Pages: [1] 2 3 4 5 6 ... 10 Next