Show us your square wave

[Martin.M]

Oldies @work

Mini-Tek Type221, reading from a EMG Pulse Generator



1967 Mini-Tek Type323, reading from a EMG Pulse Generator


cccp: C1-73 the 323 clone


greetings
Martin

[miguelvp]

Hah, I was wondering how you managed to get such a nice square wave out of a DG4000.

Here is a DG4062 (mod -> 'DG4202') and DS1054Z (mod -> DS1104Z) using the sync output:


And not cheating (using DAC output):

That explains why it wasn't 50% duty cycle

I think I'm going to hookup my video DAC to the FPGA and try 75MHz with the DAC running at 300 MHz since I need 4 points per cycle.
and I will also try to create both a 50 MHz and 40 MHz with the DAC running at 4 times the desired wave since I need two lows and two highs per cycle.

Also running the output to 5V is too much of a swing, since I can adjust the output by 0.01953125V increments I'm going to switch from 0 to 169 decimal (3.30078125 Vpp) that should give me a cleaner wave.

Here is doing a ramp:

[Yago]

Oldies @work

Mini-Tek Type221, reading from a EMG Pulse Generator



1967 Mini-Tek Type323, reading from a EMG Pulse Generator


cccp: C1-73 the 323 clone


greetings
Martin

Wow, three gems there Martin!

[Electro Fan]

A little bit off topic (so what's new?  )



- it's mostly a tutorial on times 10 probe compensation but toward the end (about 3:20) the presenter makes the point that probe compensation is done on square waves because we know what a good sharp edged (or in my words "strong") square wave is supposed to look like (which is often not the case with other waveforms) - and if we don't get a proper square wave we probably don't get any other waveforms properly displayed.  Just re-enforcing one of the reasons I think there is a fair amount of interest in this topic.

[Yago]

How do you know for fact Bernice is a "he"?
It seems every web forum has their wanna be top dog-know it all types.

Bernice

Bernice thank you for your fresh input, no doubt you have more to offer. 
Can I make the suggestion that you quote before your reply as it makes the post easier to read.
Sort of like how I've amended your last post. 

Save your breath. He's pretty deaf on that ear 

Read back through the thread a little and the joke will make sense.

[miguelvp]

A little bit off topic (so what's new?  )



- it's mostly a tutorial on times 10 probe compensation but toward the end (about 3:20) the presenter makes the point that probe compensation is done on square waves because we know what a good sharp edged (or in my words "strong") square wave is supposed to look like (which is often not the case with other waveforms) - and if we don't get a proper square wave we probably don't get any other waveforms properly displayed.  Just re-enforcing one of the reasons I think there is a fair amount of interest in this topic.

If you notice he has to revisit the compensation several times because he is using a metallic screwdriver and he is touching the screwdriver with his other hand. So use a plastic one that probably came with your probes.

[Martin.M]

gems means germaniums?

the 221 is from the 70`s, also the russian. Both use Fet and silizium parts also.
Some Mini-Tek of the 200 series have IC.
The oldest is this 323, made in the time of the glowing era. (for the money of a car)

And here re more then 3 scopes, but I dont want to flood the forum with Oldies.

greetings
Martin

Tek, 551 


and a 7k

[Yago]

Gems, diamonds.beautiful scopes.

Post the pics in their own thread, I would love to see more of them, sure others would too.
I'd wager there's some great info you have from restoration work you have done (guessing from the great condition they are in).

[joeqsmith]

- it's mostly a tutorial on times 10 probe compensation but toward the end (about 3:20) the presenter makes the point that probe compensation is done on square waves because we know what a good sharp edged (or in my words "strong") square wave is supposed to look like

- kind of curious to see what is the lowest price device is that can produce a really good looking square wave at 1, 5, 10, 20, and 30 MHz? 

If I understand correctly and we agree that the edge rates, settling times, noise .....  are important for a strong looking square wave, if a generator can meet your requirements at the highest frequency, I am curious why you feel it would not meet them at lower frequencies?   

Are there function generators out there that actually fall apart at low frequencies?   AC coupled or something?   Guessing that iPOD and application would not fair well at DC.    I can believe an ultra fast edge rate TDR may not meet your day to day needs but you were clear that you wanted a square, not a pulse.     What other requirements do you have?

Besides using an actual function generator with a square wave feature, we presented using digital buffers to get a square waves.   No one called me out for my free energy square wave, but the point to this was I show using a couple of diodes to clamp a sine to get the square.    Maybe you can use what you have available to get the job done.   

It's rare I have a need for a square wave that comes out of OTS function generator.   Normally I have to put some sort of drive on it anyway to get what I need.


Like the tiny scopes. 

That's a nice little setup with the FPGA and video DAC.   You could make a real nice ARB with that.  This video shows one I made that puts out the signals to an fuel injection system so it thinks it's on a motor.   


The sound (crappy) is even digital.  The only thing analog is the power supply and drivers.  Pretty much DC compared to what you have.




 
 

[Pjotr]

Brings up the question: "What is the use of a strong looking square wave" 

[miguelvp]

That's a nice little setup with the FPGA and video DAC.   You could make a real nice ARB with that.  This video shows one I made that puts out the signals to an fuel injection system so it thinks it's on a motor.   


The sound (crappy) is even digital.  The only thing analog is the power supply and drivers.  Pretty much DC compared to what you have.

Neat, I was the lead programmer for NHRA Drag Racing games, we did have a deal with RacePak and we integrated the game simulated telemetry into the full RacePak acquisition software (included with the game but with a license that would only work with the PC sim).

We did simulate everything and it was cool to actually use the same data acquisition software that the teams used.

I'm amazed the game still sells for quite a bit of cash since it's a 10 year old game
http://www.amazon.com/NHRA-Drag-Racing-Top-Fuel-Thunder/dp/B0002EA5Z4
And the previous version still holding on price as well and that's 14 years old
http://www.amazon.com/NHRA-Drag-Racing-Main-Event-PC/dp/B00005Y3YX

Edit: as I recall I think the launch MSRP was only $20, I guess they are hard to find

Sorry no motorcycle drag racing. And I don't see a penny of those sales since Moto1 is long gone, so it all goes to Valuesoft I would think. Of course the online servers are long gone.

Back on topic, I did misplace the DAC but just found it, so I'm going to do some tests.

[pedroteck]

What frequency signal Pedro ?

Don't really remember the settings but its about 1.5 Khz 1 vpp from the internal oscillator .

[Yago]

What frequency signal Pedro ?

Don't really remember the settings but its about 1.5 Khz 1 vpp from the internal oscillator .

Thanks Pedro, and welcome to EEV too

[Electro Fan]

- it's mostly a tutorial on times 10 probe compensation but toward the end (about 3:20) the presenter makes the point that probe compensation is done on square waves because we know what a good sharp edged (or in my words "strong") square wave is supposed to look like

- kind of curious to see what is the lowest price device is that can produce a really good looking square wave at 1, 5, 10, 20, and 30 MHz? 

If I understand correctly and we agree that the edge rates, settling times, noise .....  are important for a strong looking square wave, if a generator can meet your requirements at the highest frequency, I am curious why you feel it would not meet them at lower frequencies?

I didn't mean to imply that if a generator can produce a good looking sine wave at one frequency that it would not be able to produce a good looking sine wave at a lower frequency.

I'm pretty confident that if a generator can produce a good looking sine wave at any frequency that it will do as well or better lower frequencies.

The question was just aimed at trying to determine the lowest price point a generator could produce a good looking sine wave at the various frequencies I mentioned.

[Electro Fan]

Brings up the question: "What is the use of a strong looking square wave" 

Well, uh, keeping track of bits when doing computing and networking....

[TMM]

Here is a DG4062 (mod -> 'DG4202') and DS1054Z (mod -> DS1104Z) using the sync output:

Hello TMM,

my signal looks different with the DS1104Z.
The same signal in the second image is of a MSO2302A (org. MSO2072A).

Peter

Interesting. It could be that my 50ohm termination isn't the best and is ringing a bit - i've got a BNC tee on the scope input with an ebay spec terminator on one side and 1m of RG58 going to the function gen on the other.

[Electro Fan]

Rigol DS2202, DG4000:

I hope your DG4000 wasn't set to 50% duty cycle

That was from a Rigol DG4000 series at 40MHz with a rise time less than 2ns?  Must be either a DG4162 or maybe a DG4102.  Either way, impressive.  (I'm betting you had it set to something other than 50% duty cycle.)

Yes it is DG4162 and output is set to 160 sine wave. The scope is connected to sync out connector which gives 40 MHz square wave pulse when output is at 160 MHz sine wave. Rise time is about 1.5 ns measered with DS2202 (BW set to 300 MHz option).

What does a square wave look like at 40MHz when it is connected to Channel 1 rather than Sync Out?  Thx

[TMM]

Rigol DS2202, DG4000:

I hope your DG4000 wasn't set to 50% duty cycle
https://www.eevblog.com/forum/testgear/show-us-your-square-wave/?action=dlattach;attach=130307;image

That was from a Rigol DG4000 series at 40MHz with a rise time less than 2ns?  Must be either a DG4162 or maybe a DG4102.  Either way, impressive.  (I'm betting you had it set to something other than 50% duty cycle.)

Yes it is DG4162 and output is set to 160 sine wave. The scope is connected to sync out connector which gives 40 MHz square wave pulse when output is at 160 MHz sine wave. Rise time is about 1.5 ns measered with DS2202 (BW set to 300 MHz option).

What does a square wave look like at 40MHz when it is connected to Channel 1 rather than Sync Out?  Thx

See reply #120 

[EV]

What does a square wave look like at 40MHz when it is connected to Channel 1 rather than Sync Out?  Thx

See reply #120 

Here are square waves from sync out and output with my DS2202 and DG4162.

[Electro Fan]

The 4162 is pretty respectable - congrats and enjoy!

[Jay_Diddy_B]

Hi group,

Here are some measurements from some classic HP generators. All the measurements are 10 MHz, 4V p-p into 50 Ohms.
All measurements made with a Tektronix TDS744A that was hacked and calibrated to the 1GHz TDS784A.

HP 8116A function generator




HP 8112A pulse generator



HP 3325B function generator




These are all analog based units, no DDS.

Regards,

Jay_Diddy_B

[alterbaron]

Siglent SDG1025 measured using Siglent SDS 1072CML 70Mhz oscilloscope.

The generator was configured to output a 1Vpp signal into a 50 ohm load. The scope doesn't have a 50 ohm mode built-in, so I hooked up a BNC triple jack with a 50 ohm terminator at the scope input. Infinite persistence is turned on for every image. The scope was left to settle for about 30s before capturing each image.

Rise time is measured at just over 5ns, which is pretty good. (Bandwidth can be approximated as 0.35 / (rise time), so we can't expect any faster than a 5ns rise on a 70MHz scope.)
Actual rise time should be <5ns.

If I crank the output up to 5Vpp (max output voltage into 50 ohms at 25MHz), the rise time is measured as 6.8ns.

The last couple of pictures show the waveform generated when configured for 1MHz 1Vpp output. Rise time is pretty much the same.

[Wuerstchenhund]

Siglent SDG1025 measured using Siglent SDS 1072CML 70Mhz oscilloscope.

[...]

If I crank the output up to 5Vpp (max output voltage into 50 ohms at 25MHz), the rise time is measured as 6.8ns.

Forget the 25MHz screenshots, they show garbage if your scope only has 70MHz bandwidth (which isn't enough for a 25MHz square wave).

[alterbaron]

Forget the 25MHz screenshots, they show garbage if your scope only has 70MHz bandwidth (which isn't enough for a 25MHz square wave).

Good point, thanks.

[rf-loop]

Forget the 25MHz screenshots, they show garbage if your scope only has 70MHz bandwidth (which isn't enough for a 25MHz square wave).

Good point, thanks.

Here is SDS1072CML frequency response.


Here is your SDG1025 square


Square wave is series of sinewaves 1. in this example 25MHz fundamental freq. Then harmonics, 3,5,7,9,11,13...etc (levels depending risetime (and other things in real signal shape))
Look freq response even 5th is attenuated over 3dB and 7th attenuated over 6dB

It explain well your square wave images including also my knowledge about SDG1025.

25MHz square fundamental f is 25MHz, then next harmonic is 75MHz, then next 125MHz and next 175MHz and next 225.   (if we have enough fast risetime it continue lot of more.)

With SDG1025 risetime SDS1072CML is just barely enough for this SDG square but it do not show SDG square shape exactly (it can see just there in top after rising endge an bottom after dalling edge. Now here come also SDG1025 risetime to limiting factor... so we do not need very wide BW oscilloscope. (also SDG1025 own filters... there is same rules about produced signal harmonics levels.... )

Some may wonder why I need 1GHz oscilloscope for 100Hz square wave (But really not for SDG1025 any waveform). Of course, depends risetime and how far forward we need go with harmonics and so that they are not attenuated too much.

Pure sinewave is easy, it is only fundamental freq and it is all. 100MHz sinewave need 100MHz oscilloscope (or some over if level accuracy is needed and if scope do not have flat response for stated freq band.)

Every other signal than pure ideal sinewave have harmonics and if we need inspect this some signal using oscilloscope its BW need include all important harmonic frequencies with enough accurate level.