Products > Test Equipment
FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
CDaniel:
I replaced that crappy cheap power supply with a transformer and linear stabilizators . Doesn't matter if the transformer is inside or not , as long it's a good one ( with some shielding ) .
Miti:
There's nothing wrong with the power supply other than the stray voltage that can be easily corrected. But if you're having fun, sure, why not?
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/1525/
rhb:
I sent a pitch to @"Siglent America" for an SDS1204X-E loaner for 2-3 months to do a side by side comparison to the GW Instek MSO-2204EA a couple of days ago. No response yet. They are both Zynq based DSOs with comparable features. The Siglent being about 1/2 the price of the Instek once you buy the LA and AWG options.
The FY6600 FP FW is looking unlikely as a PM to fremen67 did not produce a reply about getting the source code. But people do travel on business or take vacations, etc. So it might still happen.
The FP is a pretty simple state machine. My experience is almost entirely exotic DSP routines running on high end workstations and larger. But I don't see anything that worries me. It's just another thing I've not done before. That was my stock in trade my entire career. And the thing that made going to work so much fun. But at 65 with $50/bbl oil I can't ever go back to that.
Now visual persistence on a DSO, *that* scares me. My LeCroy DDA-125 has up to 32 S of persistence and then infinite. The latter is easy, but I can't figure out how you subtract what came in 32 S ago and remove it without eating a huge amount of resources.
All of this is tightly intertwined with the corruption of higher education and the cost of even a very modest test bench. Most of my electronics efforts were when I had only a Heathkit IO-18 5 MHz recurrent sweep scope and Radio Shack VOM and DMM. All my signal sources were built from datasheet circuits on perfboard.
Realistically, less than 5% of the population is university level science, engineering and math material. And that's all we need as a society. We need similar proportions of mechanics, plumbers, carpenters, machinists and such. But the mania for trying to make silk purses out of sow's ears has destroyed education for all except the autodidact.
Unfortunately, lathes, milling machines, table saws, wrenches, DSOs and such are so expensive as to be out of reach for most and a serious barrier to the autodidact.
The Zynq and Gnu/Linux have been strong drivers in reducing the cost of DSOs. A FOSS FW stack would reduce the NRE costs. If I can write Verilog code which is portable across the Zynq and Cyclone V, the two FPGA lines with embedded ARM cores, then the barrier to market is lowered substantially and bug fixes become much easier. During the workstation wars in the early 90's I ported 500K lines of VAX FORTRAN to six different Unix systems. After doing the first 4, the last two took 4 hours. That was arguably the most important lesson of my career. Develop and test simultaneously on as many systems as you can a hundred lines or so at a time. I wrote two 15,000 line libraries on that contract that never had a bug reported in over 6 years. Though the test system did catch when Sun failed to set errno properly after a call to getcwd(3C).
Fundamentally I am doing what research scientist/programmers do. Things I've never done before. That's why it's so much fun.
And the pain of having limited financial resources, doing all the HW upgrades on a V 3.0 FY6600 and then it borking itself is quite palpable.
But, Johnny, be good.
Johnny B Good:
--- Quote from: CDaniel on December 05, 2018, 11:47:27 pm ---I replaced that crappy cheap power supply with a transformer and linear stabilizators . Doesn't matter if the transformer is inside or not , as long it's a good one ( with some shielding ) .
--- End quote ---
That's true enough. The point I was making was that the bulky transformer(s) could be kept outside of the case, allowing the rectifier and smoothing cap to sit where the original smpsu had sat, leaving ample space for the three converter modules in the space between the front panel and the PSU location and still allow a 50mm cooling fan to be fitted in the bottom of the case in the remaining space to the rear of the PSU location, above which said fan, would be the ideal location to fit a 0.1ppm oscillator board (10MHz with the original clock on the MB replaced with a 5x pll multiplier chip or else as I've done, a 50MHz unit feeding the now vacated clock chip location) mounted at a rather jaunty 45 degree angle to keep it well ventilated with the incoming cooling air and free of the heat pollution it would otherwise suffer if mounted in the original clock chip location. In my case, this also improves the internal airflow by virtue of it acting as a deflector to direct the airflow more forcefully towards the front so as to increase the amount of air flowing past the heatsinked opamps.
This leaves the option to fit a better grade of smpsu with a shielded transformer that obviates the nonsense of connecting the output ground return rail to the half live mains voltage via a 1 or 2 nF Y class capacitor as is, annoyingly, an all too common practice with such small Class II smpsu wallwarts and commodity PSU boards used in low wattage mains powered devices.
The quest to find a suitable low leakage 12 to 15 watt rated wallwart is pretty hopeless but amongst my collection, I did discover three Nokia 5.7v 800mA phone charger wallwarts which read only 6.5 to 10.5vac on my 10Mohm DVM with respect to ground. I actually broke open the one of the three ever so slightly different implementations which had been not only screwed together but also glued (the other two were held together by only three screws in one case and two screws and a clip release in the other). Stupidly, I had assumed all three were identical in the finer detail of their construction, choosing on the basis of the one with the lowest leakage voltage reading only to discover that this was the one that not only needed the two screws to be remove but also the use of a junior hacksaw and some leverage with a screwdriver to crack it open. >:(
Never mind, I can use it to replace a similar wallwart cct board that I'd fitted into an ITX 140W PSU box to beef up its weedy 100mA 5VSB rail. The extra 0.7v will nicely compensate for the anti backfeed diode I used to stop the existing 5VSB from causing this supplementary 5VSB cct board to go into an overvolt shutdown state. It can go into my FreeNAS spares box for now. :)
What I haven't yet done is check for the presence of common mode induced switching hash on the output lead. Looking at the one I broke open, it's not obvious as to whether the transformer is one with a screening foil layer between the primary and secondary windings to properly account for the lack of that dreaded Y class 1nF emc bodge capacitor.
It'll be interesting to see whether it's a manufacturer's decision to simply omit the capacitor to emulate the capacitorectomy mod I've already done with the original PSU or whether they've actually justified such omission legitimately by using a screened transformer to meet the EMC directive. From what I've seen, I suspect not.
I think I might land up attempting to rewind the low voltage secondary of an existing 12v 1.5 or 2 amp wallwart transformer so as to insert a screening foil of my own. I've certainly got plenty of such wallwart smpsus to experiment with. :)
Regards, Johnny B Good
beanflying:
Interesting reading back on this flawed but really good value for money Box as it gets to EOL. There are some very cheap 50MHz units on evilbay at present if anyone is in the market with not to many $$ to spend as of today.
Mine after 15 months or so is about to get mothballed (Replacement is a Siglent 2000X) rather than sold for the few $ I might get for it so I chased up the last versions of the Windoze software and any updated Labview drivers and such to pack away with it.
Overall unlike some here my experience has overall been a positive one after sorting out the floating power supply and with a little trial and the correct tongue angle improving some levels on the board. Frequency has always been out by a bit but generally this is a non issue and if it was I checked and tweaked a few counts if needed.
Sub 10Meg for the complete software package that allows Arb Signal creation and driving the front panel via USB kicks the butt of the Siglent by comparison and as per the couple of comparison waveforms @30MHz Sine and 10MHz Square it holds up fairly well against a Generator at current pricing 10 times more $$. Coin toss for the Sine and suffering a little on the square.
Remembered fondly as it goes to the 'cupboard' to maybe never return :)
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