Recent Posts

1

Microcontrollers / Re: RIP Z80

« Last post by brucehoult on Today at 07:00:12 am »

Cool, I hope it'll work with the sifive/t-head/WCH implementations. I really would not want stuff like https://discourse.llvm.org/t/rfc-prestacked-annotation-to-solve-risc-v-interrupt-stacking-mess/74120 proliferating

I don't have a problem with that proposal at all, or indeed even see the situation as a "mess".

Some people are used to hardware saved registers on other ISAs and want that feature on their RISC-V processors, and probably more manufacturers than at present will (in my opinion) waste transistors that could have been used for better things (or just use less silicon) on duplicate register sets (worse) or a FSM to stack registers.

Maybe the people who want to implement/use this will agree on a single spec for it, but as it's pretty much 100% "we think it give us a competitive advantage" thing I wouldn't hold my breath, at least in the short term.

That's pretty much inevitable with a community-owned ISA. You can see it as a disadvantage, but I see it as a strength.

And I think @jnk0le's proposal is both very easy to implement and solves the problem neatly. It makes perfect sense.

2

Test Equipment / Re: New Zoyi multimeter+oscilloscopes - ZT-70xS, up to 50MHz/250MSps (nov 2022)

« Last post by ksxx on Today at 06:55:55 am »

Would you mind sharing what version firmware the Zoyi 703S used in your testing has? Thanks!

fw was 1.32. I now tried 1.35 and there is no change in the results (as I would assume).

3

RF, Microwave, Ham Radio / Re: Transistor tester

« Last post by Calambres on Today at 06:48:12 am »

Those chinese testers work so-so with Ge trannies.

Their firmware is based on an older version of the OSHW k-firmware with issues discerning Ge BJTs from JFETs. If you have a tester with a genuine ATmega you could flash the m-firmware which comes with a few additional checks to tell Ge BJTs and JFETs apart.

I have some of those units, even a couple with genuine ATmega processor (AY-AT) and have never experienced a Ge trannie being identified as a JFET. On the other hand, the measurements are off, always reading high beta and leakage.

I have not investigated the reflashing method. It seems to me a bit cumbersome from what I've seen. Is there a "dummies guide" to do it easily?

4

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

« Last post by dietert1 on Today at 06:47:21 am »

I downloaded their laser range finder app note from https://downloads.sciosense.com/Files/ScioSense_AS6500_DMA_V1-package-1-3.zip. I successfully compiled the project for STM32L476 using CubeMX and EWARM - with all references resolved. So that's a good starting point. They capture the interrupt signal into a variable My_INTN_State and use that one to control the main application loop. A bit unusual is the use of both rising and falling edge for interrupt.

Regards, Dieter

5

Beginners / Re: Checking for noise in resistors

« Last post by Calambres on Today at 06:42:39 am »

From the era of tube gear, many signal tracers have a "NOISE" mode switch built-in. Example Heathkit IT-12.
That applies high voltage bias to the probe about 115VDC/1.7mA and with the audio amplifier you can listen to the result.
A noisy resistor or capacitor with bad dielectric can be flushed out. It was a common problem in the day.

Yeah, that's the Heathkit unit I talked about in a previous post in this thread. It is unobtainium here in Europe at least at a reasonable price.
That was more or less the circuit I was trying to make, albeit somewhat modernized, i.e.: no tubes 

6

Test Equipment / Re: new killer scope in town - a true game changer from R&S - RTB2002 & RTB2004

« Last post by electronix27 on Today at 06:41:09 am »

@ Rydda

Thanks for the very detailed and informative post.  At least I now know someone else has experienced this.

Russell

7

Microcontrollers / Re: SD Card reliability in SPI mode

« Last post by betocool on Today at 06:40:23 am »

The card is not physically damaged, and yes, on one occasion a Windows format fixed the 'reading directory' issue. I haven't tried formatting the card using FatFS, that functionality is not yet implemented in the micro. Another thing I could try to "fix" the card. Not something I'm keen on before getting the data.

Cheers,

Alberto

8

Repair / Re: Tektronix SC502 Alt and Chop mode fault

« Last post by BlownUpCapacitor on Today at 06:39:40 am »

AHH DAMMIT. I SHORTED U360 WITH THE GROUNDING SLEVE AT THE END OF MY OSCILLOSCOPE PROBE TIP WHILE I WAS PROBING AROUND. THE WHOLE ERROR CHANGED NOW.

I guess I'll go purchase some new 7472 chips. These seem are though as the ones on digikey are SMD, and the ones on Ebay are expensive. Good bye money!

New symptoms: CH1 mode works just fine and dandy. CH2 mode works well, but the trace gets dimmer when in that mode. Alt mode shows only CH1 with a dim trace, same with chop and CH1-CH2.

9

Repair / Re: Tektronix 2225 vertical display problem

« Last post by BlownUpCapacitor on Today at 06:37:17 am »

Possibly a burnt input resistor. Some other guy somewhere here had a burnt input resistor on a 22xx series scope. It's soldered directly on the BNC so not hard to check.

10

Beginners / Re: Is this 220v capable board? (Dewalt DCB095)

« Last post by soldar on Today at 06:36:16 am »

I have a Ryobi drill and charger bought in the USA. The charger says 120 V and it definitely is only for 120 V. I used to use it with a stepdown transformer but one day, I do not know what I was thinking, I plugged into 230 V and it promptly blew the filter cap. After replacing it the charger worked again. At 120 V, of course.

You would think they would make the chargers good for 120 and 230 V but they don't and they make separate adapters. My guess is the do this to maintain separation of markets. In the USA the products are cheaper than in Europe and they try to put obstacles to private or grey market exports.

I am guessing this is what Dewalt tries to do too. Even though the unit is good for 230 V they try to scare you into thinking it is not.