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Author Topic: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator  (Read 129104 times)

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Offline swgertsch

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #125 on: January 27, 2016, 05:52:17 PM »
Well, I finally got a better understanding of what triggers do on the FY3224S. There is no relationship to the counter even though all the trigger settings are accessed under the [Count] button on the front panel.

Setting a Trigger
A trigger is used to initiate a pulse of the CH1/MF waveform, n number of times, as defined by the CP_CNT (CyclePlus_Count) value. There are three triggering modes: manual (Manual Trigger), external (Ext Trigger), or channel CH2/SF frequency (CH2 Trigger). Here are the pertinent command that control triggering...

tt0   Trigger manually. A trigger event is initiated by physically depressing the [ADJ] knob on the front panel.
                        Note: A “manual” trigger event cannot be initiated programmatically.

tt1   Use the signal from the BNC connector labeled Input on the front panel for the trigger.

tt2   Use CH2/SF frequency as the trigger.

tnn   Set number of waveform cycles to output (CP_CNT value), where n is the number of cycles.

                        Note: Changing the CP_CNT value programmatically causes the trigger mode to change to manual trigger mode.
 

Offline pdereus

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #126 on: January 28, 2016, 08:42:29 AM »
Indeed, I think they just clogged it under the counter option to save another button and perhaps the fact that in trigger mode, you can set the number of cycles (Count) that will be out put on a trigger event. For example set the main frequency to 1 kHz and trigger on say 50 hz (either from an external or channel 2 source) and CP_CNT to 10, you will get 10 waveforms of 1 usec each repeating every 20 msec.

I'm still looking for a problem to solve with this feature  :-/O 
 

Offline tedbar

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #127 on: February 09, 2016, 07:00:23 PM »
I bought the FY3220S. It is V1.2 and I have applied the trick to get it to 24MHz which worked, on power up it reports that it is an FY3224S.

The problem I have (which existed before changing the max freq) is the output at low frequencies. Below 100Hz the square wave deteriorates badly and becomes unusable. Please see the attached images at 100Hz, 10Hz, 1Hz and 0.1Hz

Is there a firmware update that will fix this? Or any fix for that matter?

thanks
Ted
 

Online nctnico

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #128 on: February 09, 2016, 10:17:37 PM »
Turn off the AC coupling on your scope!
Neat the frequency hack worked on yours though. You are lucky...
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline tedbar

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #129 on: February 09, 2016, 10:49:31 PM »
Duh - thanks

Yes, it is great that the fix worked :)
 

Offline skarven

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #130 on: February 10, 2016, 06:44:52 AM »
I bought the FY3200S 24MHz a few days ago. To my use it works, but it seems to have some issues.
I haven't tested much, but here is one problem I have found so far.

In what I would call BURST mode where CH1 is triggered by CH2 to give CP_CNT pulses, it will give an extra spike about half the peak value of the real pulses. A count of zero will give only the spike. I have attached a print from a SIGILENT SDS 1052DL.

The spike i about 20ns long and comes where the next pulse should have started. This is an annoying thing when testing burst input to a microprosessor. On the scope it shows up only now and then with 500MSa/s, but my 100MHz analog scope shows it very well.

skarven
 

Online cdev

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #131 on: February 11, 2016, 10:29:47 AM »
These are all new function generators so they really should fix glitches, maybe with new firmware.

That will be the test whether they are in it for the long haul, or are a fly by night operation.
 

Offline erpalma

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #132 on: February 27, 2016, 03:33:10 AM »
Hi guys, does anyone know the opamp used in this generator? I mean the ones in the output stage. I need to know the maximum current output of CH1/2.

Thanks!
 

Offline Wiesel

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #133 on: February 27, 2016, 06:22:28 AM »
Output stage uses THS3002I (if you search for the datasheet, search for THS3001).
Here is an overview:
Code: [Select]
  High Speed
– 420 MHz Bandwidth (G = 1, –3 dB)
– 6500 V/µs Slew Rate
– 40-ns Settling Time (0.1%)
  High Output Drive, IO = 100 mA
  Excellent Video Performance
– 115 MHz Bandwidth (0.1 dB, G = 2)
– 0.01% Differential Gain
– 0.02° Differential Phase
  Low 3-mV (max) Input Offset Voltage
  Very Low Distortion
– THD = –96 dBc at f = 1 MHz
– THD = –80 dBc at f = 10 MHz
  Wide Range of Power Supplies
– VCC = ±4.5 V to ±16 V
 

Offline erpalma

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #134 on: February 27, 2016, 08:43:18 PM »
Output stage uses THS3002I (if you search for the datasheet, search for THS3001).

Thank you very much! So THS3002I is the dual version of THS3001 right? And I think that each channel uses two opamp in parallel like in the 5200A, isn't it?

From the specs (much better than AD812) it seems there is no need to replace it!
 

Offline Wiesel

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #135 on: February 27, 2016, 09:13:09 PM »
I'm not 100% sure but IIRC they use only one stage for the output. The other maybe for feedback.
 

Offline erpalma

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #136 on: March 04, 2016, 12:42:10 AM »
Just received it! But why the hell it's still using 9600bps in 2016!! The waveform uploading is really slow :(

Unfortunately the only way to fix this issue is to edit the firmware :/
 

Offline pdereus

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #137 on: March 04, 2016, 04:03:55 AM »
If you're using their supplied software, its even worse as there are quite some pauses built in to their protocol. With the LabView interface I've created I can upload a waveform in about half the time. Of course, if they used higher baudrates this would be even less of an issue.

More annoyingly IMHO is the fact that sending commands over the interface disturbs the waveforms (e.g. setting a new frequency causes a slight interruption in the signal) :-//
 

Offline gearhead

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #138 on: March 09, 2016, 10:18:45 AM »
I found the unbranded FY3224S Function generator on the Banggood.com site.
I have purchased many things there,no problems at all, and shipping time is very good
Right now this unit is selling at $69.99 with free air or direct shipping to the US.
It appears to include a software disc, USB cable,2x coax cables with alligator clips and power cord.
http://prntscr.com/acvpn4
Here's a link the product:
http://www.banggood.com/FY3224S-24MHz-Dual-channel-Arbitrary-Waveform-DDS-Function-Signal-Generator-Sine-Square-Wave-Sweep-Counter-p-1014034.html

I believe I am going to order one soon as i only have a 2Mhz FG and an RF generator.
« Last Edit: March 09, 2016, 10:48:40 AM by gearhead »
 

Offline LogicalDave

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #139 on: March 10, 2016, 05:16:08 PM »
I was just using my Feeltech FY3224S and felt something biting me...the culprits turned out to be electrons...I was getting a shock.  When I measured AC voltage with a multi-meter from any of the ground points on the Feeltech (e.g. the outside of the BNC connectors) to AC ground, I had around 19vrms.

I opened my unit and the power supply is clearly designed to be isolated.  There is no DC continuity between DC ground and AC Hot or Neutral.  However, something is wrong because there is a steady 19-20vac between the BNC grounds and AC safety ground.  Would someone else please check whether their unit is isolated?
« Last Edit: March 10, 2016, 07:34:47 PM by LogicalDave »
 

Offline skarven

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #140 on: March 10, 2016, 06:16:40 PM »
I connected my scope to ground on the FY3224S (No ground connection). THere is a 100Hz "ripple" with an amlitude of app. 19.5 Volts.
I is quite high-impedance though. A 10k resistor will reduce it to about 1 Volt. This should give a current of about 0.1mA.

I do not know if it "should" be like this, but I think this is rather normal with switch mode power supplies. The oldfashioned transformers are better and produce less noise too!
 

Offline LogicalDave

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #141 on: March 10, 2016, 07:09:27 PM »
Hi SKarven, thank you for checking and for the quick response! 

Connecting my scope to any BNC connector ground on the FY3224s (no ground connection from the scope) shows a switching pattern (not a sine wave) at 60Hz that is 82volts peak-to-peak and ~20vrms; that's why I could feel it.  Fortunately, as you pointed out, the current is low (less than 1mA) so it does not appear to be a major safety hazard...at least not for humans. 

However, I'm much less confident that 82vpp AC will be healthy for many of the circuits I connect to the signal generator.  I've sent an inquiry to Feeltech; it will be interesting to see what they say.  In the meanwhile, I won't be connecting anything to my FY3224s.
 

Offline skarven

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #142 on: March 10, 2016, 09:22:10 PM »
Here is how the signal looks on my generator. I have a 50Hz 230V mains.
And I agree, too high voltage for many applications. One solution would be to ground the thing to AC ground and let that handle the current, but this will of course create problems with ground loops... The only good solution would be a isolation transformer on the mains, but this will add so much to the cost that it might be better to buy another Signal Generator.
It would be very interesting if someone with a different Signal Generator could make the same measurements.
 

Online nctnico

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #143 on: March 11, 2016, 05:11:10 AM »
I have the same effect with my FY3200. It is caused by the mains filter in the switched mode power supply. An isolation transformer isn't going to help here. An option would be to disconnect the mains filter towards the ground of the generator or (better) mount a grounded power inlet.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline LogicalDave

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #144 on: March 12, 2016, 12:49:16 AM »
NCTNico: I suspect you are right.  My PS board is heavily hot-glued to the chassis, but there is an EMI filter with two Y-caps.  I'm going to try to dig out the power supply board from the hot glue and see what the story is.  I wonder if I'll find some safety caps connected from AC mains to DC ground instead of earth ground.
 

Online nctnico

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #145 on: March 12, 2016, 12:52:37 AM »
From the photos I think the large blue capacitors are the ones connected to ground. It will be much easier though to put a grounded IEC inlet in the case.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline LogicalDave

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #146 on: March 12, 2016, 01:37:04 AM »
Those are the Y-rated safety caps.  There is a third that bridges the HV and LV sides of the transformer.  I'd rather not connect the DC outputs to earth ground because that can introduce other problems; the DC ground should float.  Worst case, perhaps I'll replace their PS with a linear supply which should be quieter anyway...and safer.  It looks like the supply is +/- 12v, +5v, +3v3.

However, at this point, I'm curious and would like to figure out what is wrong with their design.  Unfortunately, they used a *lot* of hot glue to secure the PS board and it's really hard to get out; I'll need to revisit this when I have a bit more time.
« Last Edit: March 12, 2016, 01:50:29 AM by LogicalDave »
 

Online nctnico

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #147 on: March 12, 2016, 04:02:26 AM »
Those are the Y-rated safety caps.  There is a third that bridges the HV and LV sides of the transformer.  I'd rather not connect the DC outputs to earth ground because that can introduce other problems; the DC ground should float.
This generator isn't designed to have the DC ground floating. For EMC and safety reasons it is better to ground the outputs.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline erpalma

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #148 on: March 13, 2016, 10:37:43 PM »
I was thinking about replacing the psu with a linear one too. For my current project I am more worried about ground loops and related issues rather than (human) safety. I will connect the siggen to a custom pcb which, in turn, it's connected through two usb ports to a desktop computer. This pcb is powered by a linear psu where the ground can be lifted from earth, but the two usb connectors are earthed through the PC psu. At some point I will also probe the signal on the board with my oscilloscope, so another ground->earth connection will be established. Of course my pcb will connect all grounds together.

Should I ground lift the oscilloscope in order to have a single earth connection?
 

Offline Aruck

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Re: FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator
« Reply #149 on: March 14, 2016, 12:33:31 PM »
I just ordered one of these, can't wait to get my hands on it.

I wonder what would happen if a bigger company designed a function generator around the $100 price point. Seems to me that there is room for improvement. I'd pay an extra 30 dollars for better grounding, better phase control and a faster baud rate.
 


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