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1
Karel, this is interesting. I normally use the built-in screen and so never noticed the discrepancy. I wonder what they gained or saved by truncating the screen rather than scaling it to fit. Just a case of ease of implementation?
2
Beginners / Re: 30V 10A power supply keeps blowing 2N3055s
« Last post by Hero999 on Today at 04:40:38 AM »
The smaller die was also mentioned to me. Even as the 2N3055 is very old and widely used is there any modern replacement which can be used in circuits like this? Maybe even with a more modern housing, as this might be the mounting easier and probably even the thermal parameters might improve.
I replaced the 2N3055 with the MJ14002G in my voltage clamping circuit and it worked perfectly, but it's much more expensive, possibly out of the original poster's price range. Other possibilities are the 2N3771G or MJ802G.

One thing to bear in mind is that, it's not just the current, voltage and power ratings which are important but the safe operating area. Some high current, high voltage, transistors are designed to be used as a switch, rather than a linear power amplifier and are completely unsuitable for this application.
3
Test Equipment / Re: New Rigol DC Load DL3000 Series
« Last post by Rbastler on Today at 04:40:01 AM »
Glad I went for the Maynuo  :phew:
4
I'm not sure about your local conditions in Argentina but I would have expected that you would have been able to pick up cheap 8-bit LAs and Arduino clones on ebay from China.

I'm sorry to repeat my opinion on it being impossible to tap into the key matrix without breaking it.
5
Test Equipment / GW Instek post sales tech support?
« Last post by rhb on Today at 04:37:53 AM »
I'd like some feedback on GW Instek's tech support.  Is it any good or are buyers on their own after the sale?

I've been considering buying an Instek MSO, SA & PS (~$6k online).  After reading the manuals I put together a list of questions abut the MSO and sent them to the tech support email in Taiwan.  These did not require complex answers. Questions included the lengths of the FFTs, window function types (no triangular "Bartlett" window ??), remote disk access protocol (CIFS, NFS), time correlation of analog and digital traces, file formats, data transfer rates to a PC, etc. A total of 8 to 10 questions.  Mostly things the manuals should have stated clearly, but were ambiguous after several readings.

Rather than answer, tech support asked my location so they could forward my email to the appropriate sales office.  I replied, but after nothing happened for a day or two I forwarded the questions the US sales office myself.

Rather than answer my questions I received a reply asking if I wanted to buy or learn and if I had a Hackaday.io project (WTF?). 

The pre-sale response has made me a bit queasy about dropping $6k on Instek gear.  So I thought it a good idea to ask here.  How are they about post-sale support?  Does their "limited lifetime warranty" really amount anything?

Thanks.
Reg
6
Most keyboards (at least home made ones) are internally divided in rows and collumns, and then scanned by the controller.

The switches are then mapped to specific keycodes by the controller, who knows which keycode to send when which row/column combination is pressed.

I very much doubt your available keyboard controller will incidentally have the same keycodes on the same rows/columns.
So, you might be able to connect the keyboard matrix to your controller, but almost certainly your keys will be more or less distributed at random on the keyboard.

that said, if you can get/use any microcontroller at all, it should be possible to get the matrix connected to it, and there several opensource keyboard firmwares available.

The easiest way is using a Teensy USB Development Board and the QMK or TMK firmware.

7
Projects, Designs, and Technical Stuff / Available Audio UJTs?
« Last post by phdinfunk on Today at 04:37:34 AM »
Hi,

Years ago, I used 2N4853s for audio frequency UJT.  I got the basic design out of a book in the university library at the time.  It appears to be out of production by now.  Are there any similar good audio UJTs around?

I can build using other methods, but the oscillator with a UJT kind of sounded like a buzzsaw.  I'd like to play with that again.

--Winter
8
Yes. Also, it's kind of a "documented bug". If you take a look at the programming guide 2 - 223 (page 239)
there's written that the "Yincrement" steps are verticalscale / 25.

For example, the 4000 and 6000 series don't suffer from this limitation.
In their respective programming guides they specify that "Yincrement" steps are verticalscale / 32.

Which is weird because the 4000 series uses a display with the same number of pixels.

9
Jobs / Re: Would you hire a self taught embedded software developer?
« Last post by tggzzz on Today at 04:36:18 AM »
I learned some Unix and was connecting up to friends systems to get and send emails, which at that time were addressed using chains of exclamation points.

Youngsters today can't believe what was involved in that "bang addressing", so-called since "!" was sometimes pronounced "bang".

The key point is that you (the author) specified the name of each and every mail-forwarding computer the email addressed passed through on the way to the destination. Get one wrong, or if a machine was down, and the email bounced back in your face. That lead to many "interesting" conversations such as "have you tried going via ucbvax; that's pretty well connected and might know about kremvax".

Sometimes the past wasn't so golden!
10
That looks like a nice job.

If I remember correctly you mentioned a 330MHz working frequency so, once with the cover installed (and grounded to the case, assuming the cover is metal. Shave some of the paint at each corner.), the losses should be tolerable.
If easy to do,  you might double up on entry and exit grounds but I doubt if it will make an appreciable difference.
You might want to do a few receiver tests with the box in and out to see if you can measure any loss in sensitivity.
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