PC / Iphone / Andoid Function Generator

[Dylfish]

Hi Guys,

I purchased myself a small oscilloscope the other day and I have been looking for a function generator. Is it possible and what kind if buffer / circuit is needed to use an app from a laptop audio out (3.5mm) or a smartphone.

Is it as simple as having a modified 3.5mm audio cable with an audio wire and ground from the output device, or is it better to have some type of buffer inbetween?

I will be looking at getting a dedicated generator down the track, but at the moment I'm looking for a bit of a stop gap solution until i have more money laying around =)

Thanks

[GibsonGM]

Hi Dyl....I use "Visual Analyser", free,  <search engine>  to generate basic stuff for use with my O scope.   It does sine, square, triangle, noise, etc...pretty good, up to about 10kHz....the sine will go higher (near 22 kHz).  There are even simpler ones out there if you search.

That's all she wrote...you can use a patch cord from sound card to what you're working on, yup...but what I did was make a small amplifier (1 opamp), gain variable up to 25x.  PC Card >>  little amp box >> out to my circuit under test.   I run it on 9 to 12V, connect all grounds of course.   So the output, which may be 1V or so from the PC depending on soundcard, can be adjusted to where I want it (some filters have terrible insertion loss, eat signal, so I crank it up to get adequate output from them).    Any opamp is fine for this use (no precision needed here).     

The opamp does buffer this signal, altho I am not sure if that is actually needed for the simple stuff we do at these low frequencies!    Probably helps by giving you a nice low output impedance for the circuit you're testing...

Have at it!! 

[blackieNYC]

"Tone gen pro" for the iPhone is good. Gotta make up for the headphone jack impedance.

[Dylfish]

sweet, all i really wanted it for is basic testing so this seems the go, thanks guys!

[Brymus]

Hi Dyl....I use "Visual Analyser", free,  <search engine>  to generate basic stuff for use with my O scope.   It does sine, square, triangle, noise, etc...pretty good, up to about 10kHz....the sine will go higher (near 22 kHz).  There are even simpler ones out there if you search.

That's all she wrote...you can use a patch cord from sound card to what you're working on, yup...but what I did was make a small amplifier (1 opamp), gain variable up to 25x.  PC Card >>  little amp box >> out to my circuit under test.   I run it on 9 to 12V, connect all grounds of course.   So the output, which may be 1V or so from the PC depending on soundcard, can be adjusted to where I want it (some filters have terrible insertion loss, eat signal, so I crank it up to get adequate output from them).    Any opamp is fine for this use (no precision needed here).     

The opamp does buffer this signal, altho I am not sure if that is actually needed for the simple stuff we do at these low frequencies!    Probably helps by giving you a nice low output impedance for the circuit you're testing...

Have at it!! 

NICE!!!! I just downloaded it too,the new version has a LCR meter built in and the author posted a hardware circuit from the Italian Electronics magazine that makes it very high accuracy .
I need an LCR meter badly (for sorting inductor pulls and testing pulled caps) but the one I want is 499$ this price (free) is far better.
Thanks for the tip.