FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator

[DaveR]

The price was indeed $5 each, I noticed last night.  Luckily, I bought a couple for the parts box at the original price last week.

[cybermaus]

He is probably going to be disappointed: Most people active on this thread have already bought it since original message on April 5. Not many people left to buy, no more sales for the last 2 days. He may be too late with his price.....

[DaveR]

My thoughts exactly.  The early birds have already caught their fill of worms....

[sdouble]

I don't understand why you don't get them for free :
http://www.ti.com/product/THS3095/samplebuy

[soundtec]

Well it does say this down in the small print ,
** A myTI login ID associated to a corporate domain is preferred for sample requests. Update your myTI profile

Maybe its worth a try saying your a student working on a project,but again you may need to prove a connection with a learning institution to qualify,maybe if you have a friend who works in the electronics industry  you could get them to do it for you  . You never know though ,if you come up with the right story they might just decide to send you out a pair of op amps anyway ,maybe a little window dressing ,like a webpage and an official sounding email address is all they want .Better still ,tell them you already have the 3095 in your fy6600 and you want to try the new 3491 op amp in So8 package.

[plb]

Maybe its worth a try saying your a student working on a project,but again you may need to prove a connection with a learning institution to qualify,maybe if you have a friend who works in the electronics industry  you could get them to do it for you  . You never know though ,if you come up with the right story they might just decide to send you out a pair of op amps anyway ,maybe a little window dressing ,like a webpage and an official sounding email address is all they want .Better still ,tell them you already have the 3095 in your fy6600 and you want to try the new 3491 op amp in So8 package.

All to save $5??

[cybermaus]

I tried that a few times. 3 times I believe. with 3 different vendors.
Got some chips once, but the other times they never responded, so I had forgotten about that route.

[Ebel0410]

My thoughts exactly.  The early birds have already caught their fill of worms....

ebel0410( 519)   2,85 USD   2   09-avr.-18 23:28:59 Paris

I'm the last buyer who got them at that price $2.85 !
No more sells since April 9th 

[bdivi]

Plenty still available from Alibaba - starting at US $2.85.

I decided to wait for the new THS3491. It seems to be worth it :-)

[DaveR]

I decided to wait for the new THS3491. It seems to be worth it :-)

Given the huge improvements we've already seen with THS3095s, it's hard to see what extra goodness you're hoping for with the 3491s (whenever they become available).  A few extra mV on the outputs?

[Cliff Matthews]

Just curious, is the DY6600 able to add its channels together?  (*edit maybe not, don't both channels share the same ground?)

I've considered upgrading my signal gen for a while and just today W2AEW showed a novel way of producing an adjustable 3-step signal for testing transistor rise and fall times. https://bit.ly/2HcPAuL

[Diabolo]

Hello,

Does the 3091/3095 THS have short circuit protection on the OUT (output) like the original THS3002 installed ?


Diabolo

[cybermaus]

Comparing their datasheets:

THS3095:
Output current 350 mA [on 50 Ohm equivalent to 17.5V]
[no mention of current protection]
The THS309x incorporates automatic thermal shutoff protection. This protection circuitry shuts down the amplifier
if the junction temperature exceeds approximately 160°C.

THS3002:
Output current 175mA [on 50 Ohm equivalent to 8.75V]
The THS3001 incorporates output-current-limiting protection. Should the output become shorted to ground, the
output current is automatically limited to the value given in the data sheet. While this protects the output against
excessive current, the device internal power dissipation increases due to the high current and large voltage drop
across the output transistors. Continuous output shorts are not recommended and could damage the device.
Additionally, connection of the amplifier output to one of the supply rails (±VCC) is not recommended. Failure of
the device is possible under this condition and should be avoided. But, the THS3001 does not incorporate
thermal-shutdown protection. Because of this, special attention must be paid to the device's power dissipation or
failure may result.

So, strictly it does not, but with the fact you'd have to drive it above 17Vmax, or thus 34Vpp to reach the allowed maximum current, and the fact it has thermal shutdown, and the fact it has two chips in stead of one, I think we are fine.


Edit: thinking about it a bit more, it is not the OpAmp, but the 50 Ohm resistors that we'd have to worry about:

Driving it at 20Vpp Sine or 7.1Vrms, the two build in 100 Ohm resistors have to dissipate 1/2W each.
Driving it at 20Vpp Square or 10Vdc the two build in 100 Ohm resistors have to dissipate 1W each.

I think regardless of 3002 or 3095, it is the resistors that will fail if shorted for a longer time at maximum output. So no change to the short-out protection of the device as a whole. Manual states: "All channels can work more than 60 seconds when the load is short-circuited."

But I don't think I want to run 1W or even 1/2W for a 60 seconds on those resistors
At lower voltages (5Vsq would be 0.01W; 10Vsq 0.25W) we should be fine

[Diabolo]

Hello,

Start up feeltech generator, plug in an oscilloscope on CH1 or CH2 to view a signal, and move your finger on the plastic of FPGA cyclone, the generator hangs, it must be turned off then on again to work again.

I noticed that.

Diabolo

[cybermaus]

Sorry,  not here. Touched it. Rubbed it. Firmly pressed on it. Keeps working.

[plb]

Does it do it if you wear a grounded wrist strap?
Is the Feeltech common floating or grounded?
Is the scope common floating or grounded?

[thedoc298]

Another observation after the 3095s mod is that you can now get half decent output up to at least 100MHz using the two or three cycle sine wave trick.  However, attenuation of the output continues to increase with frequency - you don't get higher output amplitudes despite starting from a lower base frequency in the control software.

So just remove one 3002 and install 2 3095'S thanks info overload

[bdivi]

I decided to wait for the new THS3491. It seems to be worth it :-)

Given the huge improvements we've already seen with THS3095s, it's hard to see what extra goodness you're hoping for with the 3491s (whenever they become available).  A few extra mV on the outputs?

THS3491 is already available from the TI store and I ordered 2 devices - $10 each with free shipping :-)

Let's see how it performs compared to 3091/95. I hope it will improve even more the quality of the signal at the upper end of the frequency range.

BTW - I received my unit with 3.2.1 firmware and noticed that the output voltage is limited to 5Vpp above 20MHz. I believe this was not the case with the previous versions. Can someone confirm ?

[soundtec]

So I finally changed my unit over to the transformer based supply , I had to mount the mains socket about 5mm behind the enclosure back panel and trim the connection tabs on it and the switch to make everything fit . I used the blue 317/337 dual rail supply fed by 2x17 volts ac winding ,that combination gives up to around +/-20 volts dc ,trimable to what ever voltage you like .For the 5 volt rail I added a bridge rectifier and a filter cap to the red two ic dc-dc convertor , fed from an 8 volt ac winding .The bridge rectifier and cap can easily be mounted at various angles in relation to the board making this quite a compact arrangement ,it also wastes very little in terms of heat .
Without any load on the output signal ,the transformer and the +/- regulators run cool .With a 50 ohm load and as you wind up the output voltage, transformer ,regulator heatsink and output heatsink all have to work harder ,for now Ive only run it with the lid off .
The extra weight of the transformer and other stuff gives the unit a much more solid feel ,it doesnt move around the bench when you press the buttons anymore .I'll do some more tests with the lid on and with the thermal probe ,but Im sure everything will be within a safe margin temp wise. I'll post a couple of pics once Ive had my coffee

[cybermaus]

BTW - I received my unit with 3.2.1 firmware and noticed that the output voltage is limited to 5Vpp above 20MHz. I believe this was not the case with the previous versions. Can someone confirm ?

Always been like that.

[soundtec]

Heres how it looks now ,I mounted the iec connector with long screws and an extra nut and washer to build it out 5-6mm from the back panel. The transformer comes in at around 30va which seems a lot,it must weight 1kg or so , but the board can suck maybe 500ma on the +/- rails when both output stages are driven into 50 ohms,that winding is rated for .75 amp ,so +50% capacity on top seems like a good number. Remains to be seen how it works with the lid on

[Diabolo]

Hello,

Why always talk about the THS3095, while the THS 3091 is identical (except PD [Power Down] pin which is useless), cheaper and certainly very available ?
----
Sheet metal transformers vibrate, toroidal transformers do not vibrate and enamelled wire can be wound to obtain additional voltage for the purpose.


Diabolo

[soundtec]

 A look through the spec sheet of the various op amps show paralleling output devices can increase the output current , but 250 or so mA per 3095 is more than adequate for most purposes . I think the original smps supply doesnt have the extra current required by the 3095,or other upgrade op amps to work very well.

Ive set my rails to 13volts for now.
The signal ground Ive left disconected from mains earth ,only the transformer case and the metal magnetic/ Rf screen between psu and signal board  are permanently bonded to earth.I'll add a few extra inductor cores in the supply wires also ,just to snuff out any rf .Just one or two final fitting adjustments and I'll try it with the lid on .

[cybermaus]

Why always talk about the THS3095, while the THS 3091 is identical (except PD [Power Down] pin which is useless), cheaper and certainly very available ?

When I looked, the 3095 was either cheaper (for single units) or the 3091 completely out of stock (for single units)

And I bought some extra. With the 3095 disable pin defaulting to enable when left floating, it behaves the same while at the same time having more options.
So I'd rather have a few 3095 in the parts drawer then a few 3091.

But you are right, the 3091 is probably the default option, the 3095 the equally valid alternate choice.
Note that the newer 3491 also has a power down, so in that sense is more like the 3095.

[Diabolo]

Here is what I installed to have 2 separate AOPs ; THS3091 :
- https://fr.aliexpress.com/item/THS3091DR-THS3091-SOP-8/32786721972.html?spm=a2g0w.search0104.3.2.63f04d6cD4EYta&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10151_10065_10344_10068_10342_10343_10340_10341_10698_10697_10696_10084_10083_10618_10305_10304_10307_10306_10302_10059_10184_10534_308_100031_10103_441_10624_10623_10622_10621_10620,searchweb201603_25,ppcSwitch_5&algo_expid=e1d2b25f-7a5b-4642-a647-02f098dfc3ac-0&algo_pvid=e1d2b25f-7a5b-4642-a647-02f098dfc3ac&priceBeautifyAB=0

Diabolo