Author Topic: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator  (Read 316555 times)

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Offline cybermaus

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #775 on: February 18, 2018, 06:11:58 pm »
Soo... Those 220uF 25V, are they what you feel they should have been, or do you actually have 25V instead of the underspec'ed 16V me and others were complaining about?
 

Offline Ebel0410

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #776 on: February 18, 2018, 09:14:32 pm »
You're right Cybermaus my post was not 100% clear, so I edited it.
The schematic correspond to the upgraded version I made some weeks ago.
I uploaded a new one  :D
 

Offline DaveR

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #777 on: February 18, 2018, 09:49:59 pm »
Talking of power supplies, I got my transformer on Wednesday, so I've replaced the original in mine with a linear as per the photos attached.  I set the outputs to 5.1v and +/- 12.2v, and the only component which generates any heat is the LM317 on the 5v board, which tops out at 75degC (but well within its design spec).  The transformer runs very cool, and the regulators on  the 12v board hardly get warm.  I didn't bother with a fan because a 90 minute soak test with a temperature probe inside the case showed that the internal temperature only rose to a steady 34C after an hour (10C above ambient), which I don't forsee being a problem.  Some slots in the case above the 5v board will probably lose half of the extra heat anyway, if I need to do anything at all. 

As you can see, I've also replaced the plastic disc on the encoder shaft with a "proper" knob, and this simple change has made a vast improvement in the operation and feel of the thing - I'd recommend this as a "must do" mod (I just had to move the encoder mounting board forward a couple of mm to get the shaft to protrude enough to get it into the collett of the knob).

I haven't carried out any comparative tests between the new and old PS boards yet, but I did notice as soon as I first switched it on that the oscilloscope traces appeared to be much cleaner than before, obviously due to the reduced noise level compared with the SMPS.  Everything is fine so far, after three days and several hours of operation.
 
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Offline Diabolo

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #778 on: February 19, 2018, 05:36:04 am »
Hello,

@Ebel0410.
Thanks for the schema a power supply.
The symbol for 1n5819 and YG911S2 is not correct, it indicates a zener diode but it is a rectifying diode.

Regards,
Diabolo
 


Offline DerKammi

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #780 on: February 19, 2018, 07:32:09 am »
Also added it to the git

Here it is.
I don't have double checked all the components values.

This schematic shows the upgraded version I made by myself (the new values are in red).
The stock values are also mentioned.


(edited)
 

Offline Diabolo

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #781 on: February 19, 2018, 08:13:39 am »
Oops, sorry.
:palm:

Indeed, looking good symbols are correct.
I run to buy good glasses for my eyesight.

Diabolo
 

Offline Ebel0410

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #782 on: February 19, 2018, 07:06:48 pm »
@Ebel, the relais routing is a bit strange to me as the common contact looks weird up until now. If you can draw that out that would help me. A photo from a paper drawing is fine.


Hi DerKammi,

I'll start working on that next weekend, hard stuff  :palm:
 

Offline DerKammi

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #783 on: February 19, 2018, 07:09:57 pm »
Don't worry, I soldered loose some relays of my board just 10 minutes ago and all is clear now.

And offcourse, it makes perfect sense when you see it :) As always. I'll post a small update of the schematics this evening to you show
 

Offline DerKammi

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #784 on: February 19, 2018, 09:03:27 pm »
Here is the schematic update. Onto the digital part.
 

Offline Vytautas

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #785 on: February 20, 2018, 07:27:43 pm »
Here, another guy posted what happened to his fy6600. It seems to be bricked. Though, no details are provided.

 

Offline cybermaus

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #786 on: February 20, 2018, 07:36:28 pm »
This is what typically happens if the CPU on the front board does not get any contact with the FPGA on the mainboard.

Like when you disable the FPGA because you are reading the WInbond, or if the cables between FB and MB are loose or broken.
Someone else reported a device was shipped with a loose cable, also looked like this.

I'd suggest to check the internal cables and their connectors.
 


Offline soundtec

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #788 on: February 21, 2018, 12:47:34 pm »
My 6600 arrived  , V3.2
I swapped out the powersupply for something slightly better ,although the stock item seems to have been improved a bit ,it now has 25 volt low esr caps on the 12volt rails ,and the yellow x cap, 1mohm ,and slot by the opto are back ,its on a fibreglass board marked Feeltech V1.1

I have a transformer 2x17v and 8v which I will try later once the linear regulator board arrives .

I changed the dial on the encoder too ,the original is a bit small for the fingers to grasp.

I dont like the way the heatsink is mounted on the output Ic's ,due to a difference in height it doesnt seem to make good contact , I have two 3095 output ic's ,so I'll sort the heatsink out when I get those soldered in .

I tried the version 5.5 software ,one weird thing was that it seems not to respond when I switch on or off the channels via the front panel ,not sure if this is only one way communication here.

I still have to do some proper tests to check voltage and frequency cal .
 

Offline soundtec

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #789 on: February 21, 2018, 01:05:27 pm »
Here's a photo with the upgraded PSU.
Slightly higher current and extra caps and inductors on the +/- rails .
« Last Edit: February 21, 2018, 01:15:24 pm by soundtec »
 

Offline DaveR

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #790 on: February 21, 2018, 03:49:21 pm »
Here's a photo with the upgraded PSU.
Slightly higher current and extra caps and inductors on the +/- rails .

Maybe it shows that Feeltech are taking note of, and acting on, what's being discussed on here - even though they're not letting on?  I bet they are taking a keen interest in the reverse engineering developments, with a view to a future model!
 

Offline DaveR

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #791 on: February 21, 2018, 03:55:26 pm »

I tried the version 5.5 software ,one weird thing was that it seems not to respond when I switch on or off the channels via the front panel ,not sure if this is only one way communication here.


Yes, I noticed the same thing.  I could have sworn v5.3 was two-way, but maybe it's a false memory.  I'll try reinstalling the earlier version and get back to you.
 

Offline soundtec

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #792 on: February 21, 2018, 10:16:39 pm »
Hi Dave ,
The pic above is another +5-12+12 supply pulled from a dvd player ,
It has inductors on all the rails ,and a second smoothing caps after ,I even seen some switch modes with two inductors and three caps at the output of each rail .
Some reported that the caps on the feeltech psu 12volt rails were only 16 volts , the one I have has 25volt rated low esr caps at the outputs of each of the +/- ,only the 5 volt rail gets an output inductor and second cap ,also a low esr with 16 volt rating.

Either way when I turn up the output voltage of the generator it tends to pull down the 5 volt rail by a few hundred millivolts , theres likely some signal currents in the simple psu causing this interaction . Most decent equipment you find with switchmodes follow them with 78/79 type regs so noise is mV on the rails .Someone also suggested screening of the switchmode ,as there well known for radiating RF mush into other parts of the circuit . Im kinda just working through improving switchmode performance now ,but ultimately I'll most likely go old school Transformer/linear regulator later ,of course this presents its own electromagnetic screening issue which is expensive and difficult to reduce,upside is no rf problems.
« Last Edit: February 21, 2018, 10:38:36 pm by soundtec »
 

Offline DaveR

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #793 on: February 22, 2018, 04:58:36 am »

Hi soundtec - the software IS two-way, but not constantly: if the FY6600 is on when the software is started the settings on the generator are read into the software, but after that they are read only when the "Load" button at the right of the program window is clicked.  That must be what I half remembered from the two or three minutes I played with it a few weeks ago.

You've got me thinking now about alternative power supply sources, as I've got a decent quantity of old satellite receivers and dvd players / recorders stashed in the loft.  I think I'll have to open them up and see what useful bits I can scavenge from them.  Most of them were top quality models when I bought them, so there may be some hidden gems to unearth, with a bit of luck.

Dave
« Last Edit: February 22, 2018, 05:00:09 am by DaveR »
 

Offline Scratch.HTF

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #794 on: February 22, 2018, 09:27:43 am »
With regard to the circuit at Reply #791: at the THS3002 amp, the gain figure is 3.986 with a 10K input termination resistor and 4.006 without this resistor; changing this resistor to 33K results in a 3.999951 gain factor which is very close to a perfect 4.
Notably, the sine filter is not switchable and that there appears to be no frequency compensation including through full scale DAC current control for high frequencies.
To preserve waveform fidelity without the need to change waveform data depending on the output level range, the output levels are set by controlling full scale DAC current via its external voltage reference pin which the level is set by an auxiliary DAC.
There is significant jitter at output frequencies which have a division ratio at anything other than an integer against the DAC clock (fixed at 250 MHz) e.g. 250 MHz / 50 MHz = division of 5 has no jitter under ideal conditions while 250 MHz / 40 MHz = division of 6.25 has significant jitter (1.6 MHz).
I still don't know why the DAC clock is fixed at 250 MHz... an Arduino bootloader could be customized for the ARM microcontroller so that we can load custom firmware easily.
If it runs on Linux, there is some hackability in it.
 
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Offline soundtec

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #795 on: February 22, 2018, 10:32:33 am »
Thanks for that info Dave,

Ive been researching quietening switchmode psu's, assuming you have enough voltage to spare just adding a linear regulator after may not have much effect on high frequency noise ,LC filters ,both common and differential mode are a good idea though .

One benefit of the switcher is that it can withstand short term(100ms) drop outs in the mains supply and still maintain its voltage across the load, where a linear will certainly drop out with even something like 10ms duration of a mains fluctuation.
This might be important for the 5 volt rail ,less of an issue for the +/- 12 volt supplies on the op-amps I would imagine.
Would be interesting to hear from someone with design experience with switchmodes.                             
 

Offline DerKammi

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #796 on: February 22, 2018, 03:28:07 pm »
With regard to the circuit at Reply #791: at the THS3002 amp, the gain figure is 3.986 with a 10K input termination resistor and 4.006 without this resistor; changing this resistor to 33K results in a 3.999951 gain factor which is very close to a perfect 4.
Notably, the sine filter is not switchable and that there appears to be no frequency compensation including through full scale DAC current control for high frequencies.
To preserve waveform fidelity without the need to change waveform data depending on the output level range, the output levels are set by controlling full scale DAC current via its external voltage reference pin which the level is set by an auxiliary DAC.
There is significant jitter at output frequencies which have a division ratio at anything other than an integer against the DAC clock (fixed at 250 MHz) e.g. 250 MHz / 50 MHz = division of 5 has no jitter under ideal conditions while 250 MHz / 40 MHz = division of 6.25 has significant jitter (1.6 MHz).
I still don't know why the DAC clock is fixed at 250 MHz... an Arduino bootloader could be customized for the ARM microcontroller so that we can load custom firmware easily.

Thanks for the 33k resistor change. Like those small changes which help in make this device a little bit better every time.

Together with the adj. resistor we can actually "calibrate" the unit pretty nicely.
 

Offline cybermaus

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #797 on: February 22, 2018, 07:28:26 pm »
I still don't know why the DAC clock is fixed at 250 MHz... an Arduino bootloader could be customized for the ARM microcontroller so that we can load custom firmware easily.

These are two separate topics right? (unsure because they are in one sentence)
Assuming indeed they are two topics:

Fremen67 already discussed the possibility to STMduino this. But alas, the needed pins for the default arduino sketch upload are used for other purposes on the FB, as are the ones for the serial uploader. We would be stuck using a STlink, even for the STM32duino code. So no easy upload, and thus we may as well burn firmware without loosing space to a bootloader.
Anyway, STlink is also easy, so not worry about it too much.


Not discussed here, but I did also think about changing frequency on the DAC to work around 4ns quantization jitter from a theoretical point of view.
But that is not so easy. PLL's typically have fixed ratio's, so even if you add more ratio's, you increase the number of perfect integers, but they are still among a sea of jittery real numbers.

Right now the FPGA is hard coded on a 50MHz x5 PLL. Even if we were to start tweaking the FPGA as well as the STM, I suspect we could only get fixed ratio;s. x4. x4.5 x5.
It would give us more points with no jitter, but still not all of them.

In my opinion, we'd need a VCO instead of a XO+PLL to get full variable clock and avoid quantization jitter, but it would give back classic jitter and frequency drift instead.




 

Offline Val

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #798 on: February 22, 2018, 09:38:20 pm »
Output frequency calibration.

It is possible that I missed a similar discussion before.

Many people complain about frequency accuracy and stability of FY6600.
After about 20-30 min frequency is relatively stable, but a reference oscillator lacking accuracy. My generator, for example, has 50,000,215 Hz reference frequency. It is no means to adjust this oscillator.

At the same time FY6600 allows for the output frequency calibration by firmware using the following procedure:

1.   Put the back main switch in “OFF” position.
2.   Press simultaneously “Power” and “CH1” buttons on the front panel and put the back main switch in “ON” position.
3.   Waite 3-4 seconds and release both front buttons.
4.   On CH1 select the highest output frequency for your generator model. Set an amplitude of 0,3-1,0 V.
5.   Press “SYS” and then “More”.
6.   Now on the screen you can see “Oscillator” and on display 10.000.000.000 MHz
7.   Press F5 to go to frequency calibration.
8.   Connect a frequency meter to CH1 output.
9.   Using cursor and the dial obtain reading of the frequency meter the same as set on the generator. If measured frequency is lower – dial should be rotated CCW, if higher – CW.

After calibration press the “Dial” and then CH1 to return to normal operation.
73, Val
 
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Offline soundtec

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Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
« Reply #799 on: February 22, 2018, 10:25:37 pm »
Thanks for that Val ,
Ive been through every inch of this topic and I can't recall any internal cal procedures like that mentioned before ,How did you find out about it ? and is there anymore hidden menus?
 


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