Feeltech FY6600
« on: January 17, 2018, 10:15:41 PM »
Ive taken a bit of a gamble and ordered  one of these function generators ,theres a lot of horror stories ,but at the price hopefully it works out .
Seems like theres quite a few corners cut by the manufacturers to keep price down ,most of which can easily be fixed with little effort or expense
Theres been a few hickups with the programming /code in the unit as well ,and the supplier isnt offering software updates online only if the unit is returned to the factory .Firmware V3 and 3.1 are to be avoided ,V3.2 is the current offering and seems to be working ok.

Heres a link to another site where a group have started to try and reverse engineer the product due to lack of any reasonable alternative from the manufacturer when their machine bricked itself .

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/


 Theres plenty of good tips on raising the performance of the unit here too ,power supply is weak and most likely needs to be replaced or suplemented . Some have gone for a full on linear supply others have uprated the switchmode .Unit also comes without a mains earth connection,so first thing is an IEC mains socket on the back , many reported getting shocks and a quick multimeter test from the sheild of the bnc connectors to real ground revealed upwards of 100 volts .
Im thinking of trying a hybrid approach , (20va) 1:1 isolation transformer in front of the switchers just to get galvanic isolation from the mains.

Im also thinking for small tube projects a shaver transformer which supplies HT and also runs a switchmode for heaters might be worth a try ,that way you have your cake an eat it ,proper mains isolation with the efficiency of switchers .

 I just wonder though,ever see the spark when a wall wart switcher is plugged in ? makes quite a crack as the big first filter cap charges , a small transformer ahead of a switcher is certainly going to limit that inrush spike ,maybe a mains rf filter between the transformer output and the switchers will help kill any RF hash trying to find its way back through the windings .

 I'll be trying a few experiments in the coming weeks , but if anyone see's a good reason not to try this approach please let me know.
Thanks again.



ruairioflaherty

Re: Feeltech FY6600
« Reply #1 on: January 21, 2018, 01:05:14 PM »
OK, I'll bite  :)

My main question is why?  I don't mean that to be in any way dismissive (I have countless projects that make no rational sense but are interesting to me for all sorts of reasons).

For audio frequencies a DAW and typical interface will be lower distortion, lower noise, have balanced outputs and have entirely predictable gain structure once you know how it's set.

For RF my sense is that these units get pretty rough as frequency increases, and great RF generators like the Agilent 33120a (15 MHz) can be had for $250 on the bay.


Re: Feeltech FY6600
« Reply #2 on: January 21, 2018, 02:41:22 PM »
Hi Ruairi ,
Thanks for taking the time to respond to my post .
Yes I had reached a similar conclusion ,the distortion specs arent so great on the FY6600 for sine waves.
One of the main reasons I bought  it was the ability to modulate,vco and the extra inputs , Im hoping I can use it to take a signal from a rotary encoder on my transformer winding project ,and translate the values into control signals for a traverse winding arrangement  with a stepper motor and ball screw .

Analog audio is my main focus ,so the bandwidth of this unit will more than suffice for my purposes .
One idea I did have for making a computer based  audio signal generator was to use one of those usb xmos boards and by feeding one channel with phase + and the other with phase - ,derive a balanced output ,samplerates go upto 384khz ,all the other convertors I have only go to 96khz ,so 40khz or so output signal is going to be the max I can get out . I do want to be able to send analog signals in the 100khz plus region .

The other thing is there is a bunch of people working on modding ,hacking and generally improving the FY6600 over in EEV blog so for the cost of the unit(80 bucks  :-[) I felt it was worth a gamble.  Id love to be able to populate my test setup with state of the art stuff ,but I cant justify the expense ,at any rate 95+% of the repairs I do get sorted with my eyes and a multimeter .

So thanks again for chiming in ,Im very grateful for the pointers in the right direction.
I'll send you a pm and we can join the dots on what remains of the Irish music scene.

ruairioflaherty

Re: Feeltech FY6600
« Reply #3 on: January 21, 2018, 04:29:56 PM »
Hi Ruairi ,
Thanks for taking the time to respond to my post .
Yes I had reached a similar conclusion ,the distortion specs arent so great on the FY6600 for sine waves.
One of the main reasons I bought  it was the ability to modulate,vco and the extra inputs , Im hoping I can use it to take a signal from a rotary encoder on my transformer winding project ,and translate the values into control signals for a traverse winding arrangement  with a stepper motor and ball screw .

That sounds like a fascinating project.

Quote
Analog audio is my main focus ,so the bandwidth of this unit will more than suffice for my purposes .
One idea I did have for making a computer based  audio signal generator was to use one of those usb xmos boards and by feeding one channel with phase + and the other with phase - ,derive a balanced output ,samplerates go upto 384khz ,all the other convertors I have only go to 96khz ,so 40khz or so output signal is going to be the max I can get out . I do want to be able to send analog signals in the 100khz plus region .

Have you looked at the Digilent Analog Discovery 2?  It's a pretty extraordinary toolset for the money and the generator out has true differential outputs. 

https://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

I'm about to pick one up in the next few weeks to help with characterizing transformer non linearities for a project idea.  They've just added an impedance analyzer to the Waveforms 2015 software.



Quote
The other thing is there is a bunch of people working on modding ,hacking and generally improving the FY6600 over in EEV blog so for the cost of the unit(80 bucks  :-[) I felt it was worth a gamble.  Id love to be able to populate my test setup with state of the art stuff ,but I cant justify the expense ,at any rate 95+% of the repairs I do get sorted with my eyes and a multimeter .

Absolutely worth the gamble and a fun way to learn about the mechanics of such a unit.  Love the EEVBlog community.

I am unbelievably over equipped on the bench considering my skill set, as you say so often a multimeter is all you need.

Quote
So thanks again for chiming in ,Im very grateful for the pointers in the right direction.
I'll send you a pm and we can join the dots on what remains of the Irish music scene.

Got your PM!  Will shoot you a proper reply tonight.

Re: Feeltech FY6600
« Reply #4 on: January 21, 2018, 04:50:53 PM »
Cheers Ruari,