portable handheld function generator

Thread Starter

relicmarks

Joined Oct 13, 2006
355
HI

I'm looking for a very small portable handheld function generator that will give me

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log

Who makes one that is very cheap and small?

Just a cheap brand name that is very small so its portable
 

Thread Starter

relicmarks

Joined Oct 13, 2006
355
ya i have

been looking at the KITS but i can't find one

Any cheap brand names?

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log
5.) DC Offset

I have found some KITS but they don't have the shape/symmetry control which i need

I guess i would have to get function generator IC chips & build it DIY? that supports all of these parameters?

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log
5.) DC Offset
 

someonesdad

Joined Jul 7, 2009
1,577
You don't define what you mean by "cheap" and "small" (weight or physical dimensions or both?), but AFAIK, what you're looking for doesn't exist -- at least, I've never seen one on the web nor as a project for a hobbyist.

However, I think this would be an excellent product opportunity for a manufacturer. Put it into a box the size of a paperback book perhaps 25 mm thick (or smaller) and make it battery operated. The frequency range could be from e.g. 1 Hz to 0.1 MHz. Cost would be $100 or less. It would run from e.g. three AA batteries. Maximum amplitude would be 4 V p-p into a large impedance, 2 V p-p into 50 ohms. It would have two amplitude ranges, selected by switch: 1 to 100 mV and 0.1 to 4 V. Pot adjustments would be those little PCB-mounted ones with the approximately 10 mm adjustment wheels (the frequency adjustment should be a better pot though). There would be both banana jacks and a floating BNC female connector for output. No display is needed. A small LED would indicate that the unit is on.

I suspect this is eminently doable with a DDS architecture in one or a few ICs.

Hmm, maybe it should run from a 9 V battery so that it could provide TTL level output...
 

Thread Starter

relicmarks

Joined Oct 13, 2006
355
cheap i mean under $100 dollars
Small i mean handheld portable not a desktop function generator

surface mount would be better cause its small

The only thing i found to be cheap is to buy the function generator chips that supports doing these parameters

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log
5.) DC Offset
 

wr8y

Joined Sep 16, 2008
232
relicmarks:

You, sir, have GOT to visit hamfests once in a while! ;)

I have seen some real deals on test equipment at hamfests in the USA. Not sure you can buy a NEW one for under $100, but anything is possible at a Hamfest!

You can find local Hamfests listed at arrl.org !
 

Thread Starter

relicmarks

Joined Oct 13, 2006
355
Ya i went to a couple of really old surplus stores that have alot of old oscilloscopes and function generators but they are so big and heavy and the price is high too

Look at how this company got a function generator with SHAPE/symmetry control inside a small box

http://www.amazon.com/dp/B000JJHJQU/ref=asc_df_B000JJHJQU930256?smid=ATVPDKIKX0DER&tag=googlecom09c9-20&linkCode=asn&creative=380341&creativeASIN=B000JJHJQU

Look at the SHAPE control diagram symbols how it changes the triangle waveform and squarewaveform
 

wr8y

Joined Sep 16, 2008
232
You might look at the websites of:

Long's Electronics
Ten-Tec USA (the bunch in Tennessee)
Jameco
Ham Radio Outlet (HRO)

there is another one, can't THINK of the name, I have their catalog at home. MAN, I just am drawing a blank here! I'll be home in about four hours and TRY to remember to grab the name and post it. Can't believe I can't remember the name - they make a lot of inexpensive test equipment - we order from them maybe twice a year.
 

studiot

Joined Nov 9, 2007
5,003
Go to good stage suppliers and look for some stage audio test gear, Phonic, Roland, Teac etc.

But they won't come cheap.
 

SgtWookie

Joined Jul 17, 2007
22,201
Here is a basic sine, square and triangle wave function generator kit (1Hz-1MHz) for about $40:
http://www.electronickits.com/kit/complete/meas/fg500k.htm

Here is the manual for the kit:
http://manuals.elenco.com/manuals/fg-500k.pdf

The kit as designed does not provide for waveform symmetry adjustment, DC offset, nor frequency sweep. However, the symmetry inputs to the XR2206 are available, if you would choose to connect them to something - like a 25k pot. You could also add a sweep function by connecting an additional circuit to pin 8, and enabling the sweep using pin 9 (FSK input). A DC offset might be a bit more problematic, but could possibly be arranged using an opamp to provide an artificial ground reference. If you were to do that, you would likely need to add a negative power rail or 2nd battery.
 
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Thread Starter

relicmarks

Joined Oct 13, 2006
355
SgtWookie do you know any function generator IC chips i can get that will do all of these parameters?

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log
5.) DC Offset

How do you think the designer did the LFO for this? what do u think he did or used?

http://www.amazon.com/dp/B000JJHJQU/...SIN=B000JJHJQU

I think the company used a IC op-amp function generator that has a SHAPE/symmetery control

But i can't find a schematic that has a IC op-amp function generator that supports all of these's or some

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log
5.) DC Offset

Don't they make function generator IC chips that will do all of these?
 

SgtWookie

Joined Jul 17, 2007
22,201
SgtWookie do you know any function generator IC chips i can get that will do all of these parameters?

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log
5.) DC Offset
Nope, sorry.
The XR-2206 will do much of it, and that Elenco kit I posted a link to uses a single XR-2206 function generator. The MAX038 was a much more capable function generator, but the factory that made them was destroyed.

Most lab function generators nowadays use digital synthesis techniques; that way they can generate waveforms of arbitrary shapes.
How do you think the designer did the LFO for this? what do u think he did or used?

http://www.amazon.com/dp/B000JJHJQU/...SIN=B000JJHJQU

I think the company used a IC op-amp function generator that has a SHAPE/symmetery control
It's probably using opamps such as the TL071/TL072/TL074 family. It's only operating in the audio spectrum, so the frequency requirement is low.
But i can't find a schematic that has a IC op-amp function generator that supports all of (those features.)

Don't they make function generator IC chips that will do all of these?
Nope, not a single IC that I know of, sorry.
However, you could combine a couple of XR-2206 IC's; use one to generate the ramp for the frequency sweep, and another for the signal output.

You'd still need a method for generating the offset. I already mentioned using an opamp as a virtual ground. Just connect it as a voltage follower, with a pot on the noninverting input between Vcc and Vee.
 

Thread Starter

relicmarks

Joined Oct 13, 2006
355
I read The Intersil ICL8038 and Maxim MAX038 function grnerator ICs are also not made anymore.

Do you think the XR-2206 is the only function generator IC chip now?

opamps such as the TL071/TL072/TL074 family. It's only operating in the audio spectrum, so the frequency requirement is low.

Do you guys know any Op-Amp function generator schematics that supports theses parameters instead of using a function generator IC chip

1.) sine,triangle,square,pulse waveforms
2.) Shape/symmetry control
3.) Start and stop frequency
4.) sweep linear or Log
5.) DC Offset
 
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