Recent Posts

1

Microcontrollers / Re: Divide clock by 3 on a ATF16V8B

« Last post by PCB.Wiz on Today at 12:35:09 am »

I don't know if this is possible on the ATF16V8B but this code will divide by 3 symmetrically only on the posedge of the clk
It's a cheat where you make a counter count to 3 and mux the output between 0, clk and 1 so I get the symmetrically from the clk input

That could be done, with some caveats.
The 16V8 has no CLK in the product term array, so you need to join 2 input pins.
Generating a CLK from an async MUX like that, exposes the risk of a runt pulse, in the handover from MUX=CLK to MUX='1'

2

Repair / Re: Tektronix DM501A repair

« Last post by CaptDon on Today at 12:34:13 am »

One thing that ALL of the 500 series modules have in common is crappy switch contacts. Flush the switches with spray contact cleaner and then just a light wiff of spray contact lube. I will get flamed for this but I used WD-40 sparingly after using a spray cleaner on all of my 500 series module switches and they work fine!! I have inherited so many modules out of various dumpsters, most marked as "Will not calibrate" and I never had to do an electrical repair on any of them!!! Only had to clean the switches and excersize them about 20 times each.

3

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.

Addit: If size matters, you could find a small MCU that has a CLK out option with /3 choice. Still needs programming, but it will be smaller than a 16V8 or CMOS counter.

4

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.

5

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.

6

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.

7

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!

8

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

9

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.

10

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.