Recent Posts

1

Microcontrollers / Re: Divide clock by 3 on a ATF16V8B

« Last post by PCB.Wiz on Today at 12:30:18 am »

Can you please tell me if this is doable, and how could I do it ? I can access to a Windows computer if needed.

Yes it is doable, with the caveat you have a 1/3 or 2/3 duty as mentioned above.

You need Wincupl, to compile boolean equations to JED and then a Device programmer to pgm the 16V8.
WinCUPL can run command line, which may help portability ?


If all you are doing is /3, you could look at other CMOS programmable dividers ?
eg the widely available HC161/HC163 can divide by 3 with an upper Qn connected to /LOAD, so the counter goes 14,15,0,14,15,0... for divide by 3.

2

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by David Hess on Today at 12:29:34 am »

In the application note: https://www.analog.com/media/en/technical-documentation/application-notes/an43f.pdf
from page 30 onwards a number of precision Wein Bridge cicuits are suggested with temperature compensated amplitude, they use a pair of matched diodes or two diodes in close contact.

That is how a sine source is leveled.  Detection can be done in many ways including a temperature compensated diode rectifier, RMS detector, or at lower frequencies even a precision rectifier.  I am sure I have seen a design where a sampler was used to synchronously detect the peak of the sine wave.

3

General Technical Chat / Re: Russia and China to Build a Nuclear Plant on the Moon.

« Last post by tggzzz on Today at 12:28:37 am »

Well, conflating "non-visible" with "dark" was a case of ostrich policy.

Words change their meaning over time.

A couple of centuries "dark" was often used to mean "hidden" or "unknown". Thus the "Dark Arts" were hidden/secret sorcery/rituals..

It is less than 200 years since the central regions of Africa became known to Europeans (e.g. the source(s) of the Nile, Congo), so it was quite reasonable to think of Africa as being the unknown/hidden/Dark continent.

Similarly, the moon did have an unknown/dark side until October 7th 1959. On that day Luna 3 returned photographs of the far side, and it ceased to be the Dark Side of the moon.

4

Beginners / Re: Question about use of Differential using scope USB port

« Last post by watchmaker on Today at 12:27:35 am »

THANK YOU David.

5

Beginners / Re: Is it safe to store CMOS devices in the AideTek ESD Boxes

« Last post by watchmaker on Today at 12:26:42 am »

You both seem to know where I am coming from.  And I had to chuckle at your replies.

Indeed, I am (was) trying to employ the inventory strategy I used in my business.  And you say that I have entered a Hell from which there is no return.

Better to face the facts.  Just looking at the cache I bought, I can see your points.

All of it is in the original bags.

OK.  So I can rationalize capacitors, resistors, trimmers, LEDs, switches and transistors.  But from there it becomes limitless.

Thank you for what I do take as the voice of experience.  The best I can do from there is to try and limit what I acquire. Keep some often used actives handy, but be prepared to search out or buy (again?) stuff.  NOW I understand why others use inventory software.  But having started with CPM, punchcards and paper tape, I HATE software.  Learned too many obsolete languages and packages.

OK.  I made my bed.  Some kind of filing system it is.

Thanks!

6

RF, Microwave, Ham Radio / Re: fake MPF102s from AliExpress

« Last post by Alex Nikitin on Today at 12:26:35 am »

MMBF4416 is from process 50.

Cheers

Alex

7

RF, Microwave, Ham Radio / Re: fake MPF102s from AliExpress

« Last post by G0HZU on Today at 12:22:25 am »

The J309 is a process 92 part and this is a bit different to an MPF102 as the MPF102 is a process 50 part.
The internal die is different and this means the capacitances will be different and so will the gm and the Idss.

8

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by tggzzz on Today at 12:22:12 am »

What could be a proved single opamp for a wien oscillator?

Anything with sufficient frequency response, and output voltage swing, and drive capability.

Since you still haven't bothered to tell us those parameters, how do you expect us to help you?

In addition, ponder the second paragraph here.

More thread-choking negativity and useless crap from tggzzz. 
He's a real thread-killer if I ever saw one!

Your question about op amps?  I use T.I. OP07's with excellent results in my low frequency sine wave oscillators.
Data Sheet link: https://www.ti.com/lit/ds/symlink/op07c.pdf?ts=1714331934514&ref_url=https%253A%252F%252Fwww.google.com%252F

Also, check out the numerous TI App Notes for oscillator designs with sample circuitry you might use as starting points. Best Regards.

The context is these threads from MajorAssBurn:
https://www.eevblog.com/forum/buysellwanted/fs-affordable-dmm-checkers-ac-reference-dc-reference-ohms-reference-etc/msg5463700/#msg5463700
https://www.eevblog.com/forum/metrology/affordable-useful-ac-dc-references/msg5438690/#msg5438690
Anybody with too much time on their hands can read those. They will, no doubt, notice that many people have made negative comments about MajorAssBurn's claims in those threads.

BTW, it isn't good practice to read the first couple of posts in a thread and then jump to conclusions without reading the rest of the thread.

9

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

« Last post by David Hess on Today at 12:21:08 am »

Unitrode had advanced replacements for the TL494, but after Texas Instruments bough them their selection guides were removed.  I think they had a current mode control version of the TL494.

10

Test Equipment / Re: Troubles with HP-8903B

« Last post by alan.bain on Today at 12:20:24 am »

Are you testing using the 8903 or an external frequency counter?  I've got an 8903A and the timebase is a fairly poor stability crystal (on mine I had to adjust the capacitative loading to be able to adjust it to within spec). However the output freq is counted with its own counter and this used to effect an adjustment so this should be stable!

It's obviously vital to know if your issues are in the source or the analyser.  The performance checks in Section 4 of the OSM are worth doing (at least the early ones).

Distortion in the source is often the fault of the ALC circuit - think mine had some leaky sample and hold caps.

Alan