Recent Posts

1

Buy/Sell/Wanted / Re: FS: Affordable DMM Checkers: AC Reference, DC Reference, OHMS Reference, etc.

« Last post by watchmaker on Today at 03:25:40 pm »

Yup!!

Interestingly, all my instruments agreed as shipped.  I cannot adjust the HP, the Keysight or the 8842.

This is indicative of "inter rater" reliability;which is a precursor to validity; which in this case would be verification against a standard such as NIST.

As for my uses, I kind of doubt I have time to get far enough along to be concerned with nano amps, let alone pico amps.  I am just starting capacitors and inductors.

I WOULD be very interested to learn where such measurements are used.  I know it is not an issue of "trivial precision".

FWIW, I have come to conclusion that the way to bring the world crashing to its knees is to end capacitors.  Who the hell knew?

Regards,

Dewey

2

Repair / Re: Tek CG5011 calibration

« Last post by nicnac117 on Today at 03:24:38 pm »

Any chance you could make it available ?

3

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

« Last post by Denge on Today at 03:24:31 pm »

Hi Both,

@ Dieter: the SPI is working correctly here as the config data I sent to the chip is read back and correspond to what I sent so I'm pretty sure the SPI communication is OK.
@ Mino: unfortunately the schematic is still a work in progress but it is very similar to yours (Pico-Fmeter-AS6501) around the AS6501 except for the 10Ω in the power lines and the 3K3 resistor in the interrupt line to the MCU.  Plus I've only one 3V3 supply.  I'm using a dsPIC33 processor but this shouldn't make any difference.
For the moment I'm testing (read: trying to get it running correctly) on a breadboard but this isn't the origin of the absence of the interrupt signal from the AS6501!

So I'm eager to receive a tip pointing me in the good direction to solve this.

4

Beginners / Re: On ground loop while connecting a Logic Analyzer

« Last post by aliarifat794 on Today at 03:22:03 pm »

If you have a DUT connected to both your laptop's USB port and the Saleae Logic Analyzer (LA), then yes, both devices would typically share a common ground through the laptop's power system.

5

Beginners / Re: Why are thermal jumpers so expensive?

« Last post by coppercone2 on Today at 03:19:58 pm »

uh read the process it requires hot pressed glowing for a long time while chemicals act on it.

you don't have bulk processes, its sintered into the shape you want. No one machines ceramic tiny parts. And you don't sinter AlN powder. You get other materials that you press and react while under pressure to form the AlN. There is some AlN powder and then there is elemental aluminum and the reactants that work in pressure in the mold (possibly with action of gas) to make the part you want. Its like sintering advanced

6

Repair / Looking for a small PCB-mount microswitch with a long stem

« Last post by Phaseseeker on Today at 03:16:47 pm »

I'm trying to fix an old laserdisc player from Pioneer, and the microswitches that are used modeswitch don't work properly (tried flooding the inside with contact cleaner, no luck); the exact parts (Pioneer DSG1015) are basically unobtanium in Europe (unless one wants to spend 50€ on a switch...), so I'm trying to figure out if I can replace them with a modern part. The problem is that the original switches are
a) very small
b) they have a fairly long "stem", with a pretty long travel and a very weak spring, so I can't just put a tact switch there.
See the attached picture. Any ideas on where to look for a part I can adapt?

7

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

« Last post by radiolistener on Today at 03:16:43 pm »

IanB suggested to use the Kill-a-watt which is kind of cheap but it's not Chinese. It's Taiwanese. The Taiwanese is not pleased if you call them Chinese.

The point was is that using blind method to determine device specification with some meter is not acceptable for medical devices. Just because it don't cover all possible modes and as result it may lead to unexpected failure of device in future and as result uncontrolled risk for the patient life. In addition any measurement equipment used for medical device testing requires to be validated.

What is the risk of smartphone charger failure? It can kill the user, you probably hear about these incidents...
Medical device should not allow such kind of risk.

8

Microcontrollers / Re: How to create custom bootloader in esp8266

« Last post by tellurium on Today at 03:13:19 pm »

There is no need to write anything.

ESP8266 ROM already has this functionality. If you pull GPIO 0 down, and reset the micro - it'll boot in the bootloader mode.
Then you can reflash it. See https://github.com/cpq/esputil#esp32-flashing

9

Projects, Designs, and Technical Stuff / Re: Heated Ferrite == Useless Ferrite

« Last post by strawberry on Today at 03:11:31 pm »

shorted one of windings = will lose all inductance except small parasitic inductance(leakage)
if you dont have LCR meter use functiongen and oscilloscope and observe transformer waveform
if core is broken somehow = low inductance (inductance equal that of air/no core)

10

Beginners / Re: RS232 intermitted issue

« Last post by aliarifat794 on Today at 03:11:15 pm »

You can try a different terminal emulation software, such as PuTTY or HyperTerminal, to see if the issue persists.