Recent Posts

1

Repair / Please help to identify component

« Last post by ValSergeev on Today at 09:09:26 am »

Hello lads.
After unsuccessful searches on the Internet, I came to you asking for help in identifying a component. It is located in the LCD panel control board circuit.
I will be sincerely glad for your help!

2

Test Equipment / Re: Vevor SDS1104 for first oscilloscope?

« Last post by kripton2035 on Today at 09:05:30 am »

if you want i2c mainly, then a small logic analyzer around $20-30, with sigrok free software, will give you better interface, more memory.
no need for a scope to mainly look at i2c. and you need memory to store all i2c sequences before analysing.


this vevor user interface seems so old ... pretty sure you can only see one i2c sequence on the screen...
the last rigol or siglent 12 bits scopes may be a little more expensive, but you can do so much more with them...

3

General Technical Chat / Re: $20,000 dollars of software or licences on a thumbdrive ?

« Last post by tom66 on Today at 09:04:29 am »

If the replacement value of the thing is $20,000 but the actual market value is less (say $5, it's a thumbdrive) I suspect it would be a criminal damage charge rather than theft but I am certain either way the thief won't be paying for it, because they usually have little to no assets.  So you'd better hope your business insurance covers something like that.

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Projects, Designs, and Technical Stuff / Re: Coulomb counter IC for coin cell products.

« Last post by Psi on Today at 08:53:45 am »

Yeah, current consumption is a bit of an issue.  They usually draw too much.

5

Buy/Sell/Wanted / Re: SALE (AU/NZ): Multicomp Pro MP710086 (Owon P4305 rebadge) at element14

« Last post by Psi on Today at 08:45:12 am »

I have that one (GWinstek GPS-3303).
Got it for NZ$200 secondhand.

The only thing I don't like about it is the update rate for the LED display, it's around 500ms and feels a bit laggy when you just want to change the voltage immediately.
Probably be fine if it was 250ms but 500ms feels a bit annoying. You move the knob and have to wait up to 500ms to see what the voltage is.

6

Test Equipment / Re: Vevor SDS1104 for first oscilloscope?

« Last post by help_me_pick_username on Today at 08:43:18 am »

It looks exactly like the Owon SDS1104.
Max Record Length: 20K is a bit low these days.

It does look exactly like the Owon model, probably rebadged.

How problematic is the max record length? I do plan on maybe using this to work on communication protocols like I2C, do you think this might be an issue?

I wasn't able to find many other competitive models in the 300-400 AUD price range. The other sigilent models being recommended here seem to be almost double the price of this.

7

Projects, Designs, and Technical Stuff / Re: Need help with _ _ _ schematic review _ _ _ for solar & supercap powered sensor

« Last post by doru.cazan on Today at 08:42:16 am »

Thanks @zilp, @Peabody!

everse leakage current is the datasheet number you are looking for, yeah. One I have lying around would be the BAV116T (5 nA max at room temperature), but no clue whether that's a good choice for your application.

The BAV116T looks good but will probably need to adjust the R3-R4 to be able to handle larger forward voltage drop; will look into it.
 

Also ... did you test that chip?

Used the chip on another project but nothing low power; have a nRF-PPK2 on order and will do as soon as it will be delivered.

it seems the circuit could be a lot simpler if you ran the ATTiny and the sensor at 3.3V

Due to supercapacitor backup for running overnight will need as much power as I can get; AVR, sensor and clock all run from 5.5V down to around 2V (will limit to 2.7V to be able to run the MCU at 10Mhz for smooth I2C communication and for reducing the processing time)

I just don't know why it's there, as opposed to making R1 200 ohms

I am not sure 100% either but the original design was tested by strange.rand so will keep it for now; depending on tests, I can replace the R1 with 200ohm and R2 with 0ohm later.

8

Repair / Tek FG502 fails at high frequency end of dial

« Last post by gcwills on Today at 08:41:03 am »

Hi all,

I have recently inherited several Tek TM500 series plugins and have managed to repair a few faulty units. A range of faults from a broken resistor at the input of a DC509 counter, a shorted tantalum cap in an AF501 bandpass filter and several others with blown indicator lamps replaced with LEDs.

However, I have a FG502 function generator which works in most settings, however it has an unusual issue with the output dropping out at the higher end of the frequency dial. The pulse and sawtooth output settings work fine with output being sustained across the extremes of the frequency dial. However when the square, triangle or sine functions are selected the output signal disappears when the frequency dial is advanced beyond 5-7 of the range. To make it even odder, this signal dropout only occurs when the frequency multiplier is set for X10, X10², X10³ but on other multiplier settings there is no issue. And to add, at lower settings of the frequency dial when the generator works fine the output frequency is accurate across all ranges of the frequency multiplier.

I have confirmed all rail voltages are correct with no ripple evident, have extensively cleaned the function and multiplier cam switches, have confirmed that the DC levels set by the frequency set pot and following opamps are correct, have tested the buffer FET Q200, Q230A and B, Q290 and Q292 and all of the diodes associated with the diode switches.

Here is the manual for the FG502: https://w140.com/tekwiki/images/1/11/070-1706-00.pdf

An unusual fault indeed! Any bright sparks out there who can throw light on this conundrum?? Cheers!

9

General Technical Chat / $20,000 dollars of software or licences on a thumbdrive ?

« Last post by MathWizard on Today at 08:39:30 am »

In some thread on here, I think some guy was working on embedded systems programming, and then Enterprise software mangement or something. Including stuff with AMD software or something he said he had $20,000 worth of, on a USB thumbdrive, and it broke. And so he would have to buy all the software or licences again.


Now I'm wondering about a legal aspect of this, like, say this thumbdrive had been stolen. Or even suppose it was built into a toy, and some bully at highschool or a bar/night club, decides to snatch it from you, and won't give it back.

Now would that count as stealing $20,000 ? So you could rightfully call the cops right away ?? What if they stomped on it, but had no idea what it was ?

I just hate bullies, so I just thought of that post I read on here.

10

Test Equipment / Re: Hacking the Rigol MSO5000 series oscilloscopes

« Last post by BTO on Today at 08:38:54 am »

Hi,

I was able to successfuly unlock all options on MSO5074 by using the phyton script rigol_kg2.py posted earlier on this forum by DrMefistO. I used the following procedure based on the experience of zauberpilz:

First, because the scope already had the patched firmware v00.01.03.03.00, I reverted it to the stock firmware v00.01.03.02.02 by using a usb stick and the factory menu (pressing SINGLE on reboot and selecting "Upgrade Firmware"). After that, I rebooted while pressing SINGLE and also did "Restore Defaults" from the same menu. After these steps, I verified in the scope (Util->Sys->Help->About and Opt List) that the firmware version became v00.01.03.02.02 and that all options were inactive.

Hi mate, I tried EXACTLY as you said and you did.
My scope is also patched and unlocked and on version 1.3.3.0.
I also have the file 1.3.2.2.
i have no problem getting into the pre-boot menu, However the upgrade fails

COULD YOU BUY CHANCE FIND THE EXACT FILE THAT YOU USED, 1.3.2.2 AND UPLOAD IT TO A CLOUD AND SHARE THE LINK
I'm wondering why my file doesn't work in this process and would like to try the exact file that you used.

I have also grabbed 2 other files from different places on this forum and they also didn't work.