Recent Posts

Pages: [1] 2 3 4 5 6 ... 10 Next
1
Projects, Designs, and Technical Stuff / Re: strange scope/ground issue
« Last post by madires on Today at 05:38:48 am »
That PSU seems to be a linear one (isolated output?) and the cause of the voltage you see on your scope is possibly just your local electrosmog. When you touch the probe tip you act as an antenna. Regarding the high value I wonder if you have set the probe to x1 while the scope thinks the probe is set to x10.
2
KiCad / Re: Burned CPU to get this.
« Last post by mdszy on Today at 05:37:49 am »
Good stuff! I really love KiCad's new 3D rendering, and I found it incredibly easy to import my own models from CAD files provided by manufacturers (provided you hvae SOLIDWORKS for converting files into a format KiCad likes)
3
Vintage Computing / Re: Recycling old computers
« Last post by duak on Today at 05:37:03 am »
I got a 15 Mbyte Honeywell disk drive with a disk pack about 40 years ago.  I was able to spin it up and read data off the heads but never went any further.  It sat in the corner of the apartment holding up an 11x17" dot matrix printer.  When 8" winchester drives became affordable, I scrapped the old drive and made a workbench out of it.  The spindle motor became a bench grinder.  A few years later, I took the disk pack apart and found four surfaces that had the oxide scraped off so it wouldn't have been really useable anyway.  The inter disk spacers look like something from Buck Rogers so I have a plan to make a retro/steampunk light shade.

Somewhere I have the voice coil assembly out of a 14" Diablo hard drive.  I was thinking it might make some sort of mass driver.

I went to a data center in the late 90's to transfer some customer data from our machine to some new disks.  They had a number of Amdahl V470s and some StorageTek silos.  They had one or two system programmer/operators there all the time just monitoring, fixing things and exchanging tapes 24/7.  Even then, I'd say the system was obsolete but it still made them money.  That part of the building didn't need heating in the winter.
4
General Chat / Re: Canyou handsolder 0203 SMD parts?
« Last post by capt bullshot on Today at 05:36:10 am »
Yes, been there, done that (but using a reasonable sized tip and 1mm solder). Anyway, no fun for my "old" eyes, ten years ago I'd have said "peace of cake". I wouldn't recommend paste and manually applied hot air, the iron works better.

5
Projects, Designs, and Technical Stuff / Re: DIY Pure Sine Wave Inverter
« Last post by 09d08 on Today at 05:35:46 am »
I added 39 \$\Omega\$ gate resistors and actually got a sine wave at the primary, but it wasn't as good as the one I got with the BJTs. My scope started to show a weird deformed waveform after a couple of seconds and I realized that the driver IC was too hot to touch (attached the new schematic just in case). If I'm not mistaken, there's nothing in my circuit that can cause the TC4427 to fail in such a way.  Nevertheless it looks like the driver IC and the missing gate resistors were the problem.

Any idea if it is possible to use an IR2110 in this case? I've never seen someone use them for anything other than half bridges but those are the only functional FET drivers I have left now.
6
Beginners / Re: Design your own SMU
« Last post by David Hess on Today at 05:35:26 am »
Also take a look at old documented curve tracer designs.  They faced a lot of the same problems and solved them in the same ways.
7
Test Equipment / Re: I don't know what this is called.... XY scope?
« Last post by james_s on Today at 05:34:47 am »
Seems what I am looking for is becoming very rare and hard to get.  I can see vector scopes everywhere but looking at its input, it does not seem to do what I wantl

What I really want to do is to render an image from HP8568/HP8566 and HP85662A on a larger screen.  Aforementioned setup has X, Y, Z, and BLANK output.  Most oscilloscopes lack BLANK, it seems.  None of mine has it.  I even thought of buying a new scope just to use it as a XYZB to VGA converter, but that doesn't seem to be a good fit either.  I have never done FPGA so that's not a viable route. 

Seems vector type anything is popular among vintage video game cloud.  Maybe they got'em all? 

HOW ELSE can I get this done??  Maybe go all the way IN and replace this CRT with VGA in 85662 and tap the output?  That'll be about $700.  Ouch.


The vector monitors used in video games have magnetic deflection and use standard CRTs, the same type used in TVs. They are generally not fast enough to work with a signal intended to drive an electrostatic CRT. Large screen electrostatic deflection vector monitors are just an incredibly specialized item that was never produced in large numbers. There are vector to VGA conversion devices that *might* cut it, or many digital scopes have a VGA monitor output however the XY mode on most digital scopes is next to useless.

You might try pointing a video camera at the screen you want to capture, it's possible that it will flicker badly and look horrible but it may end up being passable depending on the scan rates. If it does produce reasonable results then you could get a scope camera mount for your instrument and fabricate something to attach a video camera instead of the original film camera. Once you have a standard video image you can send it to any kind of modern monitor you want.
8
Projects, Designs, and Technical Stuff / FL5150 Light Dimmer Circuit
« Last post by Chet T16 on Today at 05:34:09 am »
Hey all,

I've built up a proof of concept dimmer that uses an ON Semi FL5150 dimmer controller and a Power Integrations LNK3204 demo board.

The lnk3204 demo board has been modified to give 18v output and 300mA with an LNK3206. I've also switched the live and neutral inputs. Schematic attached as rdr506.png

The FL5150 schematic from the datasheet is attached as fl5150circuit.jpg. Its actually the 120v 60Hz circuit but its the same for the 50Hz. The FL5150 derives its 17v VS power from the mains via resistor R1 in this circuit but in an effort to reduce power consumption I am feeding the output of the LNK3208 into the VS pin directly. My schematic is attached as fl5150_schematic.jpg

The problem i'm seeing is that one of the output IGBTs/FETs are not turning off. I originally had two IGBTs in there, when it didn't work i swapped them out with the same result. I then replaced them with two mosfets. The mosfets are 07N60C3's and the IGBTs are NGTB10N60R2DT4G's.

A scope trace is attached as scope.jpg

Looking at the schematics now after a few days away I'm wondering is there some offset to ground being created by the diode D2 in the LNK3206 circuit that is preventing one of the transistors turning off?



9
KiCad / Burned CPU to get this.
« Last post by technix on Today at 05:33:24 am »
I am trying to cook up a permanently installed USB NeoPixel controller. After I got the board layered out I pulled this render. The attached image is actually cropped from the actual output, since the original output, rendered on a 4K monitor, is way too large for the forum software.



The single frame 4K raytracing render is produced on an Intel Xeon E3-1231v3 processor, overclocked to 3.51GHz base clock speed, and it took me 113 seconds.

The hardware itself is a NeoPixel controller based on an Arduino-like platform. The main microcontroller is an ATtiny841 running at 16MHz. The USB interface is implemented using a Holtek HT42B534-1 in SOP-10 package.

KiCad 5.0 on 4K monitor seems a little bit too demanding for the GTX 1060 3GB graphics currently in my machine. I wonder if the AMD RX 580 with its 8GB VRAM, or some new card from nVidia, would help.
10
EEVblog Specific / Re: EEVblog #1104 - Omicron Labs Bode 100 Teardown
« Last post by DualTriode on Today at 05:31:24 am »
Thank you.

For this plot the resistor is the 50Ohm resistor internal to the Bode 100.
Same as Dave used in the video.

DT
Pages: [1] 2 3 4 5 6 ... 10 Next