Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Homebrew Lock-In Amplifier

« Last post by RoGeorge on Today at 07:10:29 am »

In case you don't have the time to build a dedicated LIA, this oscilloscope trick might be a good-enough replacement:
https://www.eevblog.com/forum/projects/oscilloscope-with-trace-averaging-as-a-lock-in-amplifier-(rigol-ds1054z)/

2

Projects, Designs, and Technical Stuff / Re: more modern version of tl494?

« Last post by xavier60 on Today at 07:10:19 am »

What's wrong with the tl494?

The output is slow archaic junk.

I have heard other people say fairly often that there are much better PWM IC out there, but nobody seems to be able to point to one with access to both inverting and non inverting pins of the error amplifiers.
I have spent many hours on digikey looking, but havent had much luck.

Voltage feed-forward would be nice

and pulse skipping too

The Tl598 seems to be the tl494 with a better output section.

And states "Internal Circuitry Prohibits Double Pulse at Either Output"

3

Power/Renewable Energy/EV's / Re: Why are all Vicor PI3 modules suddenly out of stock or obsolete?

« Last post by quince on Today at 07:08:57 am »

The Vicor modules seem "stable enough" in terms of inrush current and availability. The text you just posted is full of generalizations that don't seem to add up.

I don't know what's going on at Vicor, but it seems odd that a product regularly stocked in the thousands at multiple distributors would suddenly evaporate.

4

Repair / Re: JBC SL-2300

« Last post by lionelkjh on Today at 07:06:05 am »

Hello, and thank you for the feedback...I have the documentation for this product, but unfortunately I am looking for the diagram, or photos of the board of a functional soldering station....I measured the tension on the iron; it is located at 160v and should be around 24v...Cdt

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Projects, Designs, and Technical Stuff / Re: more modern version of tl494?

« Last post by 2strokeforever on Today at 07:05:15 am »

What's wrong with the tl494?

The output is slow archaic junk.

I have heard other people say fairly often that there are much better PWM IC out there, but nobody seems to be able to point to one with access to both inverting and non inverting pins of the error amplifiers.
I have spent many hours on digikey looking, but havent had much luck.

Voltage feed-forward would be nice

and pulse skipping too

The Tl598 seems to be the tl494 with a better output section.

6

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.

7

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).

8

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?

9

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

10

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