Recent Posts

1

Microcontrollers / Re: Dim OLED Screen replacement for Agilent Keysight U1253A U1253B U1273A U1273AX

« Last post by gamalot on Today at 11:11:08 am »

I found my U1173B and did a teardown and RE for it. The circuit diagram was not carefully organized so it looks a bit messy, but it should be readable.

2

Beginners / Re: What component is this please?

« Last post by aliarifat794 on Today at 11:10:37 am »

According to your test result it is a 1.6V, 3.2 microhenry inductor.  But I could not find any having the same outlook. I searched here: https://www.digikey.com/en/products/filter/fixed-inductors/71

3

Buy/Sell/Wanted / Re: Usps moneysaver

« Last post by wraper on Today at 11:10:31 am »

Something that accepts crypto only, no info who they are, the only contact is telegram. Certainly not dodgy and not a scam...  The only way this could possibly be working https://www.entrepreneur.com/business-news/woman-arrested-for-60-million-usps-counterfeit-postage-scam/453513

4

Repair / Re: Sony J30 PSU repair

« Last post by Harry_22 on Today at 11:08:42 am »

Good!
Please send me the photo of "white diode".

5

Other Equipment & Products / Re: Different bases on Amscope microscope

« Last post by voltsandjolts on Today at 11:06:39 am »

You may need this info at some point in the near future:
https://www.eevblog.com/forum/repair/amscope-double-boom-replacement-bearings/

6

Projects, Designs, and Technical Stuff / Re: Simple illuminated time display that can be driven over USB?

« Last post by Gyro on Today at 10:53:59 am »

I know it's not self illuminated but the epaper display has decent contrast and it wouldn't be hard to make a nice stand with front illumination. You could probably pick up a Kindle keyboard for little money these days and constantly USB power it. Timekeeping from the web over wifi.

Just a thought anyway - rather more of an interesting conversation piece than a basic clock...  https://www.instructables.com/Literary-Clock-Made-From-E-reader/

There's also a digital version for a jailbroken paperwhite (self illuminated). Make sure the firmware version can be jailbroken.... https://github.com/mattzzw/kindle-clock

7

FPGA / Re: ATF1502 programming & 'wrong' id (fake?)

« Last post by xvr on Today at 10:50:53 am »

Very strange that IDs are different. I suspect some flaw in JTAG circuitry on your board.
Do you have oscilloscope? Check all JTAG signals.

8

Projects, Designs, and Technical Stuff / Powering NeoPixels from 3.3V - Wrong but everyone does it?

« Last post by sebmadgwick on Today at 10:50:05 am »

NeoPixels are prolific, used in countless hobby, industrial, and commercials products.  They have become synonymous with "RGB LED".  There a several variants but the datasheets all specify an operating voltage of 5V, more specifically, 3.5V to 5.5V.

Nevertheless, I have seen many designs power NeoPixels from 3.3V.  I do not do this myself and will always provide a 5V supply, using a charge pump or similar if necessary.  It just seems unacceptable to me to end up in a situation where a product I have designed starts misbehaving because I ignored clear engineering data.

I am also not satisfied assuming that empirical data overrides datasheet specifications.  Just because the first ten thousand units work, it does not mean that the next ten thousand will.  Manufacturers change components characteristics knowingly or unknowingly and only the datasheet specification can be relied upon.

So my question is, can NeoPixel 3.3V operation be verified analytically, such that a design engineer can take an informed risk?

For example, perhaps it is known that the logic is 3.3V compatible CMOS but the LED Vf is 3.5V which would mean reliable operation at 3.3V but with compromised brightness / colour mixing.

9

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

« Last post by shapirus on Today at 10:44:01 am »

This is why non-FOSS licensing sucks.

10

Repair / Re: Keithley 2400 locks up when buttons are pressed

« Last post by tomn on Today at 10:38:55 am »

Thanks for the reply.

did you try the steps as outlined in chapter "Battery Replacement" of the service manual, especially the ":SYST:MEM:INIT" sequence?

Not yet, I'll try today. I'm a bit wary of losing RS-232 access (still need to get a GPIB adapter), but I think SYST:MEM:INIT should keep the settings the same...

also, i wouldn't trust the EEPROM sockets on the digital board too much, you could pull and give them a "deoxit & re-seat" treatment.

Yeah, I forgot to mention, i did re-seat them. As the self-test always passes i doubt this is the problem, but i can give them another go.

as for the key pads, a key pad repair kit for tv remotes will do the trick. iirc, the stuff i used was "gumki do pilotów" by TermoPasty.pl from a*n. i glued the new pads right on top of the button stakes without even removing the old pads, using a drop of high temperature silicone (instead of the silicone that was supplied in the kit) and letting them cure for 24 hrs. button feel is slightly "stiffer" now, but key responsiveness works like a charm since 3 years now.

Ah, i did not know this was a thing, thanks!

edit: forgot to mention: you may want to check the electrolytic caps  :horse:

There's only one or two that could be a problem for this (on the digital 5v supply). They seems fine, and the supply seems quiet. Maybe if I get really desperate I'll consider making an offering :)