Signal Generator

shane · Post by **shane** » Tue Apr 28, 2009 9:56 am

Thanks to the generosity of a forum member from the other place, I am now the unexpected and slightly bemused owner of a Goldstar 9020 oscilloscope.

It occurs to me that a useful thing to have to go with it would be a signal generator, and I see that there are various bits of sofware around for use with a laptop. Has anyone used any of them, and are they any good? Only beginner-level, of course. I don't want to confuse myself too much...

Post by **Nick** » Tue Apr 28, 2009 11:50 am

They are ok, and good if you want a precise frequency, or very low distortion. But for general use I find a bench generator far more useful. YMMV.

ed · Post by ed » Tue Apr 28, 2009 12:39 pm

Hi Shane

I have a couple of basic s/w generators, variable frequency & variable output level. If you email me(not pm) your email address I will send them.

But, contrary to what Nick says they are not ideal if you are scoping for distortion....but they are ok for gain determination etc....

I have been looking for a farnell lfm4 for simply ages, anybody got one spare????

Post by **Nick** » Tue Apr 28, 2009 2:31 pm

But, contrary to what Nick says they are not ideal if you are scoping for distortion....but they are ok for gain determination etc....

What problem do you have? My bench gen is great for normal stuff (square waves, clipping, fault finding) but it produces about 0.1% distortion, so if I am checking that I need to use the PC generated signal/

floppybootstomp · Post by **floppybootstomp** » Tue Apr 28, 2009 4:44 pm

I'm not too sure how accurate it is but I recently built a frequency generator from a Maplins kit This one here.

I already had a 12V psu (a CCTV encapsulated one) and the whole thing cost less than £25.00 to build.

It's mounted in a plastic case with a sloping front and all switches and connections are flown from the pcb to the case exterior.

Four waveforms, they look clean on my 'scope, ok for general use. Only disadvantages are no visual indicators of frequency or amplitude.

Bottom line - it was cheap

ed · Post by ed » Tue Apr 28, 2009 4:56 pm

Nick wrote:
What problem do you have? My bench gen is great for normal stuff (square waves, clipping, fault finding) but it produces about 0.1% distortion, so if I am checking that I need to use the PC generated signal/

I don't have a problem...I was just musing.....

a pc sig gen is only as good as the sound card you have.....from experience, and iffy memory of course, the vst sig gen that I run in wavelab, or the standalone sig gen, when run on the studio machine through echo or lynx are absolutely fab......

in contrast to this when the standalone gen is run on my normal pc(the internet one) the noise floor is at about -70/-65 and if i move the mouse, well you get allsorts of wierd and wonderful artifacts.....

Its unlikely that Shane would want to spend £500 on a digi interface just to run a sig gen so I was just suggesting what can happen with a normal sound card/pc set up......but, as always, YMMV

on reflection, and rereading my post I guess I was a bit too general and tarring all pc set-ups with the same brush.......it aint so!

Mike H · Post by **Mike H** » Tue Apr 28, 2009 6:29 pm

floppybootstomp wrote:I recently built a frequency generator from a Maplins kit
Four waveforms, they look clean on my 'scope, ok for general use. Only disadvantages are no visual indicators of frequency or amplitude.

I remember that! 'Course what that really needs is a reduction drive with a big pointer and a corresponding paper scale, but then you'd have to calibrate it

Mike H · Post by **Mike H** » Tue Apr 28, 2009 6:51 pm

See also this, a few DIY here:

http://www.4qdtec.com/singen.html

audio-talk

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