Hopefully we'll see a basic teardown soon.
An FPGA and R2R ladder DAC is rather common for the low cost Fgens.
I would consider 4 points for further tests:
1) Noise, e.g. from the SMPS or just from the DAC: So maybe use just a DC or low amplitude sine.
2) DAC linearity: This can usually be seen from a slow triangle / ramp.
3) Output amplifier slew rate: Many similar low cost generator run in to a slew rate limit with full amplitude and high frequency. So usually the maximum amplitude is reduces at the highers frequency.
4) There are 2 relays per output channel. So this could be an output attenuator. This has good sides, but might also limit the Offset range, when using low amplitudes.
The JDS6600 generator family has very similar functionality to the Feeltech FY3200 and the MHS-5200 generators. The JDS6600 even uses the exact same plastic case for the enclosure as the FY3200, MHS-5200. For a comparison of those other generators see:
https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/msg697718/#msg697718
From testing the FY3200 myself and reading on the MHS5200 they both are both limited in their output voltage range into 50 Ohm load without clipping or high distortion. So the first test I would suggest is:
1. Set 10 KHz sinewave with 20 Vpp/maximum amplitude on an oscilloscope with 1 Meg impedance. Then add the 50 Ohm termination and see if the output drops to 1/2 or if clipping or distortion starts happening.
On these type generators the output buffer is often slew rate limited which in turn means the output amplitude at higher frequencies is limited. So, the second test I recommend is:
2. Set a 10 Vpp 100 kHz sinewave on the output into oscilloscope with 50 Ohm termination. Then increase the frequency until maximum frequency to see if or at what frequency it starts distorting horribly.
On the FY3200 generator when you change the frequency the output waveform glitches. Ideally one would expect a change in frequency with a sine wave to step change the slope at the frequency change with no step in the actual voltage. Unfortunately the FY3200 has steps in the output because the phase as well as the frequency changes when you change the frequency. So, the third test I would love to see is:
3. Set the generator to 5 Vpp, 10 kHz sine wave and then step change the frequency to 20 kHz. Try to capture on the oscilloscope the moment when the frequency changes. If you have advanced triggering I set trigger width must be < 20 uSec and then set to capture once.
When you use two channels both outputting the same frequency sine wave with the phase 90 Deg apart it would be great to repeat test 3 to insure that both channels change frequency at the same time and with no glitches.
4. Repeat test 3 but with two sine wave channels outputting sine waves with 90 Deg relative phase.
The last requested test is really just a question of functionality. This generator can do frequency sweeps. But, can it do frequency sweeps while outputting two wave forms? Last requested test is:
5. Can you set the generator to output 2 sine waves with 90 Deg relative phase and then sweep the frequency such that both channels sweep in frequency and stay in phase lock?
In advance I thank you for any of the above tests that you could do and report back results.
The triangle waveform looks quite good - better than I remember from the MHS5200. However the scope setting is not that good to tell if the little nonlinearity is from the scope of from the generator. If would need a zoom in on details of the slope and maybe an even lower frequency. Usually a simple R2R DAC would show visible errors near the center or 1/4 of the range. There are 2 pots for each channel so these might be for adjusting at least that largest error.
The picture of the circuit is just to bad in resolution to read the chip numbers. The output amplifiers might be interesting. For the rest I would expect an AD603 or similar for the amplitude adjustment.
Are the USB and TTL I/Os isolated from the normal outputs ? It does not look like.
Here's kind of a youtube video about the signal generator:
https://www.youtube.com/watch?v=Fn76Yp-vATI#t=179.894071
There's no audio - not even a muzak track - but you get a closeup of the face of the unit being manipulated by what I suspect are Chinese hands.
Sure seems to do a lot.
>Charlie
Well, I guess we'll all find out together!
I've ordered it from AliExpress, and they'll be shipping via e-packet. So I should have it in about 3 weeks.
When it shows up, I'll share my experiences here.
Take care, all. Hope this works!
>Charlie
I ordered one of these about 10 days ago. According to Canada Post, they received it a few days ago, but haven't done anything with it.
However, the unit is on sale right now. I paid $136.86 CAD; the current price is $123.50 CAD, so maybe 10% off or so. Or a little more; I think their regular price was $140 CAD, but I got a few bucks off for being a nice guy. Heh, heh. Little do they know.
Anyway, mine hasn't arrived yet, so I can't endorse it. But for any one who was on the fence about ordering one, you can get it for 10% off right now.
Here's a link:
https://www.aliexpress.com/item/RD-JDS6600-Series-25MHZ-Digital-Control-Dual-channel-DDS-Function-Signal-Generator-frequency-meter-Arbitrary-sine/32811781657.html
It's also worth noting that they've introduced several new models; they now claim a new high frequency of 60Mhz on their most expensive model. This is for a sine wave. For square or triangle waves, they claim a maximum of 15Mhz across the board, for all their models.
Here's a link to a page listing all their models:
https://www.aliexpress.com/item/RD-JDS6600-Series-40MHZ-Digital-Control-Dual-channel-DDS-Function-Signal-Generator-frequency-meter-Arbitrary-sine/32814611834.html
I don't believe the 60Mhz claim. I'm sure there's something there, but I'll bet it winds up looking like a weak, wobbly triangle wave than a pure sine.
Anyway, for someone interested in checking it out... there it is.
>Charlie
I bet this device is nearly identical to the MHS-5200A (and higher versions), except that it has the much nicer screen (and perhaps better UI).
Hopefully we'll see a basic teardown soon.
The parts used seem to be a little more expensive (e.g. AD835 instead of lower cost AD603) than those in the super cheap versions. The amplifiers also look rather fast. Still strange that there are additional AD8017.
I finally found the higher resolution pictures. So I got a look at the DAC: they seem to use 15 lines in a thermometer style to get the upper about 4 Bits with less errors / glitches. So the DAC is not just an R2R ladder.
4. For changing the frequency when both channels are running the same frequency you say:
"I couldn't find a way to change the frequency of both channels at once, so I'm not sure if that's possible"
These generators usually have a channel synchronization mode where you lock them such than changing one channel parameter changes both channels. In the JDS66000 manual I found on line it says under the system setting menu:
4.4.2 Sync: When sync, CH1 is the object of operation. CH2 parameter will be changed with the changes of CH1 parameter. When the sync item is selected, you can press or knob to select the sync item needed, press ON softkey to select and press OFF softkey to cancel.
Could you check for the system setting sync function and try changing the frequency of two channels locked at 90 Deg phase again?
5. Perhaps with the two channels sync'ed you can then sweep two channels with a phase difference simultaneously?? One can only hope....
Again, thanks for your help in evaluating this generator and sharing.
The two exceptions are a) the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS. b) Both BNC connector cables have a very intermittent and tenuous connection when plugged into the generator. Sometimes I cannot get a solid signal without putting side tension on the leads.
To vk2seb, I enjoyed your presentation video and noted the relay click noise was masked by the incessant transducer beep. There is a way to turn of the beep and save that setting so it never sounds unless you turn it on again. Also QBY's question regarding both channels syncing. As far as can see the SYS button lets you set the frequency, waveform, amplitude, offset and duty to track (sync) chan 1 and chan 2. This is also true in the software which drives the JDS6600 through the USB port. Altogether a nice piece of kit.
Quote from: KleinsteinAn FPGA and R2R ladder DAC is rather common for the low cost Fgens.Interesting, I've haven't torn down a cheapie Fgen like this before so that explains that.Quote from: KleinsteinI would consider 4 points for further tests:
Cheers for the suggestions!
what you test ? JDS6600 ?Quote from: Kleinstein1) Noise, e.g. from the SMPS or just from the DAC: So maybe use just a DC or low amplitude sine.
DC out at 1V, AC coupled, output OFF:
Same as above, output ON:Quote from: Kleinstein2) DAC linearity: This can usually be seen from a slow triangle / ramp.
Triangle wave, 1KHz, 1Vpp:Quote from: Kleinstein3) Output amplifier slew rate: Many similar low cost generator run in to a slew rate limit with full amplitude and high frequency. So usually the maximum amplitude is reduces at the highers frequency.
Here's a sine wave, 25MHz, set to 1Vpp (but into a 50 Ohm load so what we 'should' see is 500mVpp)
Same as above, but a square wave:Quote from: Kleinstein4) There are 2 relays per output channel. So this could be an output attenuator. This has good sides, but might also limit the Offset range, when using low amplitudes.
Looks like you were right about the output attenuators, at 100mVpp setting (into 50 Ohms again), the maximum offset I can set is 0.25V;
what you test ? JDS6600 ?
I received my JDS6600/25Mhz about a week ago and I am suitably impressed with its functionality. I have put it through some tests on a Siglent SDS 2204X 200Mhz DSO and it performs rather well. The two exceptions are a) the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS. b) Both BNC connector cables have a very intermittent and tenuous connection when plugged into the generator. Sometimes I cannot get a solid signal without putting side tension on the leads.
To vk2seb, I enjoyed your presentation video and noted the relay click noise was masked by the incessant transducer beep. There is a way to turn of the beep and save that setting so it never sounds unless you turn it on again. Also QBY's question regarding both channels syncing. As far as can see the SYS button lets you set the frequency, waveform, amplitude, offset and duty to track (sync) chan 1 and chan 2. This is also true in the software which drives the JDS6600 through the USB port. Altogether a nice piece of kit.
Quote from: gby4. For changing the frequency when both channels are running the same frequency you say:
"I couldn't find a way to change the frequency of both channels at once, so I'm not sure if that's possible"
These generators usually have a channel synchronization mode where you lock them such than changing one channel parameter changes both channels. In the JDS66000 manual I found on line it says under the system setting menu:
4.4.2 Sync: When sync, CH1 is the object of operation. CH2 parameter will be changed with the changes of CH1 parameter. When the sync item is selected, you can press or knob to select the sync item needed, press ON softkey to select and press OFF softkey to cancel.
Could you check for the system setting sync function and try changing the frequency of two channels locked at 90 Deg phase again?
You're dead right, a case of 'RTFM, vk2seb' .
Here's what that looks like 10KHz->20KHz, 90 deg phase lock, 5Vpp:
So yeah, channel 2 is definitely not behaving there.Quote from: gby5. Perhaps with the two channels sync'ed you can then sweep two channels with a phase difference simultaneously?? One can only hope....
Good news: You can indeed sweep the 2 channels simultaneously.
Bad news: They don't stay in phase lock.
With a 0 deg phase set (sweeping 10KHz->20KHz):
With a 90 deg phase set (sweeping 10KHz->20KHz):
Difficult to get a capture of the whole sweep without nothing meaningful being visible.Quote from: gbyAgain, thanks for your help in evaluating this generator and sharing.
No worries at all!
Quote from: RD Techwhat you test ? JDS6600 ?Yes, all the waveforms I have posted are from the JDS6600.
Quote from: RD Techwhat you test ? JDS6600 ?Yes, all the waveforms I have posted are from the JDS6600.I just check all picture carefully, there is no problem, if you think there is some problem, please point it out, I will explain
I don't believe the 60Mhz claim. I'm sure there's something there, but I'll bet it winds up looking like a weak, wobbly triangle wave than a pure sine.
Yes! Finally! My JDS6600 has arrived!
.
.
Speaking of the feeltech product, I came across a YouTube video in which a young engineer took it upon himself to improve on the old feeltech signal generator. With the addition of a few jumper wires and a couple of components, he improved it a great deal. The funny part was when he said," I don't know why they used XXXX part. This other part is a much better match for what they're doing, and it's cheaper!"
.
.
The device has a very poor Electromagnetic compatibility,
Interference is caused by DC / DC motherboard converters.
This is noticeable immediately after switching on, if we put a probe next to it.
Sensitivity 500uV / div
Bandwidth 300MHz
The probes of the oscilloscope are connected to ground, there is no signal at the input, noise JDS6600 is very high.
Maybe it's because of your lousy way of connecting the probes to the signal generator.
First time that I see a Rigol DS2000A user (supposed to be professional player) without decent cables
If I am correct, the actual designer of this signal generator is in this thread. Maybe you can PM him with your suggestions to further improve the design.
I juste tested a JDS6600 60MHz model and it has a big problem, when set on certain frequency there is a phase shit
Form the picture it looks like the DAC is not a pure R2R chain, but more like using thermometer style for the upper bits. So maybe someone confuses the 14 I/O pins used for control with a 14 bit resolution. At least the DAC seems to work reasonably well as 11 Bit this way.
The DAC type does not have direct influence on the noise with small signals. The waveform should be generated at constant amplitude and only the following multiplier and attenuators reduce the amplitude if needed.
You can look at the delicate degree of 14bit waveform
You can look at the delicate degree of 14bit waveformDo you have a FY6600?
It can amplitude and frequency modulation and has a sync output?
I have one
I have oneWhen the frequency is tuned, the phase of the synchronized 2 channel does not change for a short time?
This is important if at 1 and 2 output an antiphase pulse signal with a deadtime, used to control the inverter.
The phase of the adjustment frequency CH2 changes because it needs to synchronize the CH1 signal
The phase of the adjustment frequency CH2 changes because it needs to synchronize the CH1 signalMHS5200A phase does not change, at least the deadtime does not intersect.
The only generator that made me for this reason.
I have just tested my instrument to adjust the frequency of the CH1 channel when the CH2 phase does not change, maybe I have an error in his understanding
Hello,
At the request of @gby
Here is the new Feeltech DDS generator 14 bits-250 msa-8192 points without R2R equipped with an Altera Cyclone IV clocked with SPXO 50mhz .
The model I bought is FY2300H-25 Mhz.
regards,
Diabolo
https://www.eevblog.com/forum/testgear/new-generateur-dds-avec-altera-cyclone4/
Form the picture it looks like the DAC is not a pure R2R chain, but more like using thermometer style for the upper bits. So maybe someone confuses the 14 I/O pins used for control with a 14 bit resolution. At least the DAC seems to work reasonably well as 11 Bit this way.
The DAC type does not have direct influence on the noise with small signals. The waveform should be generated at constant amplitude and only the following multiplier and attenuators reduce the amplitude if needed.
You can look at the delicate degree of 14bit waveform
JDS6600 Phase does not syncYes
Does the JDS6600 carry a CE mark?
I'm asking, because without it German customs may
have me return the unit or scrap it at my cost which is not funny.
Yes, I know the CE story. It basically means China Export
Having 11 Bit resolution is already quite good from an simple R2R chain at the FPGA. For me it looks surprisingly good.
Medium grade DDS chips like the AD9850 only use an 10 Bit ADC, though they use a longer table (e.g. 4096 points). With just 2048 points for a period, there is limited use of more than 10 Bit resolution though.
The staircase like waveform with quite some ringing suggests that there is no good reconstruction filter. So one can expect quite some high frequency images. The fast output amplifier also has some disadvantages here.
Some jitter in the square wave is normal for directly generating the square from the FPGA.
The jitter should not depend on the H/L ratio. It should be just a question of the 5 ns time raster. So it depends on the frequency too. This might even be the worst aspect of it. At frequencies that don't have a period that is an integer multiple of 5 ns will show the jitter. So more like low jitter only at a few special good frequencies.
I received my JDS6600 yesterday, phase tracking no problem.
The jitter should not depend on the H/L ratio. It should be just a question of the 5 ns time raster. So it depends on the frequency too. This might even be the worst aspect of it. At frequencies that don't have a period that is an integer multiple of 5 ns will show the jitter. So more like low jitter only at a few special good frequencies.This generator does not have jitter at non-multiple frequencies, unlike other budget DDS.
The jitter should not depend on the H/L ratio. It should be just a question of the 5 ns time raster. So it depends on the frequency too. This might even be the worst aspect of it. At frequencies that don't have a period that is an integer multiple of 5 ns will show the jitter. So more like low jitter only at a few special good frequencies.
Depending on how frequency calibration is done the good frequencies can be slightly different, depending on the exact quartz frequency. In principle they could use a different frequency scale - allowing only good ones (e.g. divider) and maybe warn about poor ones.
A special DAC chip is generally better than using just a resistor chain at the FPGA output. Most DACs do not offer that much of isolation between the digital side and analog output. So noise is in both cases a question of a good layout. This is still a low cost generator - so the cheap resistor ladder DAC is a kind of compromise.
The failure is to label it 14 Bit resolution if they actually only get 11 Bits.
The Resistor chain looks like 8 Bit R2R and 14 or 15 resistors thermometer style. So at best they could get something like 12 Bit resolution. Still I am surprised how good it seemed to work. If not careful, even at 8 Bits R2R one can get significant errors. One sees that with other low cost generators that call for 8 or 12 Bit resolution and only deliver 6-7. With an actual 11 Bit resolution it is already a big step forward.
Using true 14 or maybe just 12 Bit DACs is a cost factor - though they might save on the amplitude control this way.
we have updated, but we only sell at china for now. because we need to test in china, after test, and no one find the problem, so we sell to the world. it is our rule for publishing the products. all our products have this progress.
thank you for your support again
Form the picture it looks like the DAC is not a pure R2R chain, but more like using thermometer style for the upper bits. So maybe someone confuses the 14 I/O pins used for control with a 14 bit resolution. At least the DAC seems to work reasonably well as 11 Bit this way.
The DAC type does not have direct influence on the noise with small signals. The waveform should be generated at constant amplitude and only the following multiplier and attenuators reduce the amplitude if needed.
You can look at the delicate degree of 14bit waveform
I'm sorry to be rude, but I am a bit concerned about your posts in this thread. I think you are trying to imply from the context and content of your posts that you are a mere consumer who has tried the Rui-Deng model and a FeelTech model function generator. Your profile says you're from England.
However:
- you list "feeltech" in your profile
- your username is typical of the email addresses offered primarily to Chinese users by Tencent
- a google search for that username reveals other posts in Chinese in various technical forums
- your English, while adequate, leads me to believe you speak English as a second language
- FeelTech is headquartered in China, and I'm not able to find any offices in the UK
I should note that all of this is just from information you offered (your username, listing feeltech in your profile) or otherwise publicly available information. And I don't know of any reason or rule that one's profile must be correct on this forum, so I doubt you've done anything wrong. I suppose I could believe that you are an Chinese expat living in the UK.
In any case, if you do work for Feeltech (and perhaps if you designed the product you are discussing) I think you should be up front and honest about that fact. After all, who else would be better qualified to analyze the properties of a modern cheap function generator than a person who just designed a modern cheap function generator?
Thanks.
Can these problems be fixed in software and can user update the firmware themselves?
Or is this more a hardware-issue?
How can customers tell the difference between the updated and non-updated devices?
Okay, good to know.
But is there a possibility to install new Firmware via USB, or can the Firmware only be updated by programming the microcontroller via the JTAG-Header?
If the latter is the case, I'd suggest that this feature is implemented as soon as possible, as it will add significant value to the instrument. If any problem is discovered that can be corrected with a firmware-update, users can just update to the new firmware instead of buying a new unit or living with that problem. It also allows you to add features later, maybe as paid options, further adding value.
yes, we have CE mark for JDS6600, you can go to our page to check
yes, we have CE mark for JDS6600, you can go to our page to check
Where is your web page? Could you please provide your official website?
Do you maintain a list with an overview of all known hardware and software problems?
In this list you can each time add new problems and also indicate which problems that are solved.
You can give each problem a title, and classify it as a hardware problem, a software problem or a combination of both.
You can indicate in which hardware revision, and/or software revision the problem has been solved.
When customers order a product on your webstore, you can indicate which hardware revision and which software revision they will get. This avoids discussions later on, as the customer will know upfront what he will get.
Good luck in fixing all your hardware and software problems!
As you measure phase shift, use the function generator's SYNC or TTL output to drive the scope's External Trigger. That will define the input phase cleanly.
It would be great to see some pictures of the insides
Hi, everybody.
Probably this is some kindof side topic but important.
I would like to make my own program to control JDS6600 (surely specific and simpler than standard), where I can find commands description for JDS? Pls. help.
Another question (JDS is new for me) for sweep frequency mode: is there any syncro signal when JDS starts change frequensy, how to get it?
Thank you in advance
Hi tritutik,
I found a PDF of the command protocol on the included CD. It's in Chinese, so you may have to use Google Translate if you can't read it.
(I tried to copy the filename here, but the Chinese characters didn't come through. If you look in the Chinese folder, you'll see a subfolder with some PDFs in it. The comm protocol PDF is the smallest one, about 288kB.)
caned
I'd like to know if a generator like this can be a good instrument for hobby/home use?
A Rigol or Siglent generator costs no less than 300-400 $ and I don't know if it's worth to spend this money.
Is this product still in production? It is not currently listed on the RDTech aliexpress store.
Yes, they still sells, bought one 60MHz for $123 few days ago, waiting for delivery right now.
Maybe it's a bit of an odd question for a device of this class, but does this come with LabView support and drivers?
Hello
I want to buy one 60MHz function generator
but what's the difference between Feleltech, Kuman, JDS, Koolrtron 60MHz function generators?!!
for example I found the below device:
https://www.amazon.com/gp/product/B07596133Q/ref=ask_ql_qh_dp_hza
I don't know what I should do!
actually I should tune my medical board (Step response and Frequency response) and I need such a device
Best Regards
Thanks for your answer and your attentions.
is there any hand-held version for JDS6600? I want to buy the newest hand-held version.
the manufacturer has uploaded a video to show the generating of high frequency sine signal with Koolertron 60MHz:
https://www.youtube.com/watch?v=5cqbH_8tKL4&feature=youtu.be
Thanks
Yes, they still sells, bought one 60MHz for $123 few days ago, waiting for delivery right now.you buy one ? what's your order number ?
My first post on this rather impressive forum. Treat me gently.
RDTech, if there is no sync signal out to the scope, how does one sync the scope to the generator for the sweep function?
Thanks
Yes, they still sells, bought one 60MHz for $123 few days ago, waiting for delivery right now.you buy one ? what's your order number ?
504323485816309
I received my JDS6600/25Mhz about a week ago and I am suitably impressed with its functionality. I have put it through some tests on a Siglent SDS 2204X 200Mhz DSO and it performs rather well. The two exceptions are a) the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS.
I've found the mains leakage to give 312V p-p (here in the UK), screenshot attached.
I then tried testing a whole bunch of 5V USB power supplies I had, and found they all (except one, but rated only 1.2A) leaked mains voltage pretty badly.
So I'll be making a little linear 5V supply for it.
I'm not getting much luck at getting a clean signal at low amplitudes (50mV).
Apart from that, a great bit of kit.
Hi friend
thank you very much for your message
could you make a video to show the problem to let me help you ?I received my JDS6600/25Mhz about a week ago and I am suitably impressed with its functionality. I have put it through some tests on a Siglent SDS 2204X 200Mhz DSO and it performs rather well. The two exceptions are a) the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS.
I posted a screen capture of the 312V p-p mains leakage to the Ground pin of the PSU that came with the JDS6600 in the last post.
The images for problems at low signal levels is given in the two attached photographs.
The signal generated by the JDS6600 is set at 30mV, 1kHz
One picture is a screen capture of the scope itself. One picture is of the JDS6600 showing the settings.
Kind regards,
Trys
Hi Trys
thank you for your reply
you did not use our own AC-DC power supply ?
from the picture, it should be power supply interferece , and there are some inerference in your working place
please check and use our own power supply
Hi,
Yes it is your power supply that was supplied with the unit.
I will also try to reduce environmental noise, as I suspect that may also be adding to the problem.
The Function Generator is very good at higher amplitudes, it works very well and I find the controls easy to understand and use.
Trys
Forgive me for being thick, but I thought it did have a frequency counter via "Ext In"?
Hold on a little minute.
(Neck emerges from under its shell)
I've taken two photos of the screen (see below). Is the "Function Counter" the thing you are after then?
Trys
Here we go, I've tested it for you.
I put the scope's probe 1Khz compensation calibration squarewave to the "Ext In" of the JDS6600 and tried both the "counter" and the "measure". One counts pulses over time (you can stop/pause, start and clear it), and the other measures the frequency.
(Shots below).
Trys
Just a follow-up on my previous posts.
I've been using the JDS6600 DDS Arbitrary Function Generator for a few weeks now.
Now I've had more time to use it, I'm really delighted with it. Most recently I've been using it at low signal levels (at around the 20mV) looking at emitter-follower characteristics, and I can't fault it at all.
OK, so I built my own little earth grounded 5v linear power supply to feed it, but that's why I bought this version rather than the other types that are directly mains powered in the first place, as I felt I would get a clean signal like that.
The controls are easy to use, it's intuitive, and the display is really helpful as it shows the shape of the waveform that it's producing on Channel 1. The buttons themselves feel quite tactile, and very similar to the ones on my scope. They're slightly rubberized and you know you've pressed them.
The unit can be set up to start up in whatever mode you want when it first starts up too. This is really useful if you're doing a similar set of tests aver a number of sessions. So if for example, you can set the unit to start up with both channels turned off, and the first channel to be ready to output a triangle wave at 5MHz, with an amplitude of 20mV, and the second channel ready to output a sine wave of 1KHz and 1V. You can have channels default to be on or off on startup, whether you want the buttons to beep or not when pressed. That kind of thing.
The other neat thing is that it just so happens that the colours on Channel 1 and Channel 2 are yellow and light blue respectively, which just so happens to match my Rigol scope. I don't know if there is an industry standard for colour coding scopes and function generator channels or not. It makes things a lot easier trying to work out if what signal I'm looking at.
I've not tried loading up my own arbitrary waveform to the unit yet, and at the moment I can't think of why I would need to, but as it's got that functionality I may as well give it a try too at some point.
It's a very lightweight little unit, and so I've put one of those anti-slip mats under it to stop it moving around.
Here is a picture of mine, pumping out a triangle wave, 1KHz, at 30mV. The scope is on the collector of a 2N3904 set up as an emitter follower with a gain of ten. I've also got one of my other favourite things placed on top of the signal generator - a packet of Milliput.
I'm really happy with the unit. It's serving me very well.
Trys
RD Tech - You are most welcome. Thank you to your team for making such a great and useful device.
Mr Scram - here are details of the frequency and counter specs from the manual (see image below). It would be easy enough to make a little adjustable schmitt trigger for what you need.
Edited to add: Here is the part of RD Tech's youtube video showing the counter function of the device:
Thank you very much for your support , have a nice day
hope you like it and like our other products
Cheers,
Trys
The unit can be set up to start up in whatever mode you want when it first starts up too. This is really useful if you're doing a similar set of tests aver a number of sessions. So if for example, you can set the unit to start up with both channels turned off, and the first channel to be ready to output a triangle wave at 5MHz, with an amplitude of 20mV, and the second channel ready to output a sine wave of 1KHz and 1V. You can have channels default to be on or off on startup, whether you want the buttons to beep or not when pressed. That kind of thing.
The two exceptions are a) the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS.
A 5V linear toroidal PSU isn't exactly rocket science, nevertheless I'd be very interested in your circuit, and any special precautions you added to prevent switch on/off transients, any over-current and over-voltage fault protection, and your choice of low noise regulator chip.
The JDS6600 generator family has very similar functionality to the Feeltech FY3200 and the MHS-5200 generators. The JDS6600 even uses the exact same plastic case for the enclosure as the FY3200, MHS-5200. For a comparison of those other generators see:
https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/msg697718/#msg697718
Huh, interesting. Thanks for the link!Quote from: gbyFrom testing the FY3200 myself and reading on the MHS5200 they both are both limited in their output voltage range into 50 Ohm load without clipping or high distortion. So the first test I would suggest is:
1. Set 10 KHz sinewave with 20 Vpp/maximum amplitude on an oscilloscope with 1 Meg impedance. Then add the 50 Ohm termination and see if the output drops to 1/2 or if clipping or distortion starts happening.
1 meg impedance, max amplitude @ 10KHz:
50 Ohm termination:Quote from: gbyOn these type generators the output buffer is often slew rate limited which in turn means the output amplitude at higher frequencies is limited. So, the second test I recommend is:
2. Set a 10 Vpp 100 kHz sinewave on the output into oscilloscope with 50 Ohm termination. Then increase the frequency until maximum frequency to see if or at what frequency it starts distorting horribly.
So I think there are 2 interesting points here, at 10MHz and at 25MHz. Because above 10MHz the amplitude is restricted down from 20Vpp to 10Vpp (probably for slew rate reasons).
At the maximum frequency useable at 20Vpp (into 50 Ohms, so we should be seeing 10Vpp):
Looks pretty distorted. Here's an FFT (didn't use specan because I couldn't find my big attenuator )
So that second harmonic is at about -30dBc, which is out of spec (Spec says -40dBc).
At 25MHz, it looks a bit cleaner (but the amplitude is now 10Vpp out, which should look like 5Vpp into 50 Ohms):
And an FFT:
Looks to be about -40dBc, so that's roughly in spec.Quote from: gbyOn the FY3200 generator when you change the frequency the output waveform glitches. Ideally one would expect a change in frequency with a sine wave to step change the slope at the frequency change with no step in the actual voltage. Unfortunately the FY3200 has steps in the output because the phase as well as the frequency changes when you change the frequency. So, the third test I would love to see is:
3. Set the generator to 5 Vpp, 10 kHz sine wave and then step change the frequency to 20 kHz. Try to capture on the oscilloscope the moment when the frequency changes. If you have advanced triggering I set trigger width must be < 20 uSec and then set to capture once.
Here's what that looks like:
Slightly zoomed in:Quote from: gbyWhen you use two channels both outputting the same frequency sine wave with the phase 90 Deg apart it would be great to repeat test 3 to insure that both channels change frequency at the same time and with no glitches.
4. Repeat test 3 but with two sine wave channels outputting sine waves with 90 Deg relative phase.
I couldn't find a way to change the frequency of both channels at once, so I'm not sure if that's possible. Here's what 2 channels at 90 deg phase shift look like when channel 1 is increased in frequency:Quote from: gbyThe last requested test is really just a question of functionality. This generator can do frequency sweeps. But, can it do frequency sweeps while outputting two wave forms? Last requested test is:
5. Can you set the generator to output 2 sine waves with 90 Deg relative phase and then sweep the frequency such that both channels sweep in frequency and stay in phase lock?
In advance I thank you for any of the above tests that you could do and report back results.
As far as I can tell it's not possible to do sweeps on 2 channels at once.
Cheers for your suggestions!
>1 Mohm be really load 50ohm.
No.
Generator has 50ohm output impedance, which means series resistance.
vk2seb said "50 Ohm termination" and "into 50 Ohms", that means voltage get halved from the ogiginal DA output. Electoronics 101.
Tak
On your CD, "\Chinese\JDS6600 Documentation\JDS6600 Communication Protocol.pdf".
Written in Chinese, though .
On your CD, "\Chinese\JDS6600 Documentation\JDS6600 Communication Protocol.pdf".
Written in Chinese, though .It may sound strange, but there is no CD drive in my laptop.
Reading through this thread as it is the best I have found so far. Thanks for all the info.
One thing I have not seen covered (hope I didn't miss it somewhere) is amplitude calibration.
I set the amplitude for 16V square wave (talking 25Hz here so no bandwidth issues) and I find I get 16.7v measured on the scope. First question everyone is going to ask is how do you know the scope is right? The scope was actually calibrated and I fed a second signal into the scope from a power supply that had a voltage of 8.02 volts (measured with an expensive calibrated HP DVM) and the JDS6600 output was higher than +8.02V. To get a true 8V peak output I had to set the JDS6600 to 15.3V amplitude.
I was hoping there was a mechanism to adjust (calibrate) the amplitude of the output.
There are 4 trim pots on the board... 1A 1D 2A 2D... anyone know what those accomplish before I mess something up really bad :-)
I looked through the communication protocol and saw nothing that I though helped.
Hoping RD Tech has some input on getting the amplitude closer to true!!
Hello
I want to buy one 60MHz function generator
but what's the difference between Feleltech, Kuman, JDS, Koolrtron 60MHz function generators?!!
for example I found the below device:
https://www.amazon.com/gp/product/B07596133Q/ref=ask_ql_qh_dp_hza
I don't know what I should do!
actually I should tune my medical board (Step response and Frequency response) and I need such a device
Best RegardsHi friend
thank you for your message and your question
about Kuman, JDS, Koolrtron, they are from same designer . our engineer and Minghe engineer design the JDS6600. other Kuman and Koolrtron should use the brand. JDS6600 is newest version.
about the link, it is also new . it is a hand-held, JDS6600 is desktop. data and function are same
ln -s /dev/ttyUSB0 com1
sudo usermod -aG dialout <username>
Well, apparently there was something more going on with this one than the ghost voltage. The attached image is what I got after powering it up this am. Is there a way to hard reset this thing, or is it just scrap?
Hello i have the jds6600 60mhz model,when i open tha case i have see that the ic is erased!someone knows what ic is??
hi to all
iam loocking for a dds like this but have a question
its possible to adjust frequency on real time via knob like analog generators or need to set every time new frequency ?
thanks
Btw, what's with the NOISE function of this device?
I connected it to an audio amp, and what comes out is nothing like white noise, it's some sort of buzzing sound, and you can actually set its frequency.
What is that good for? (maybe I am wrong to expect white noise here, but that pitched sound is not something I'd have in mind when someone says "noise")
EDIT:
I see, it's not an FPGA function or anything but also just a fixed table for DDS, and if I set it to 1 Hz, it does resemble noise with not very much high end. I guess it would be somewhat more useful if it had a lot more points in each table than those meager 2K.
I am assuming this means that a function generator with SYNC/TTL output generates a pulse at the very beginning (0 degrees) of a waveform, which in turn could be used to trigger the sweep on the scope.
Does the JDS6600 have such a feature? I see a reference to the "TTL extension interface" in the manual, with signals TTL1 and TTL2, but no explanation of their function or usage. Are these signals equivalent to a "SYNC" output?
Please, anyone can identify what chip is inside in the red circle?