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Just bought first oscilloscope, recommendations for inexpensive signal gen

grabread

grabread

Active Member
Hi, just bought my first scope, it's a Beckman 9020. I am looking to buy an inexpensive signal generator (ebay Chinese type) Anyone have an experience of these?
Also wondering if the test tone on the scope could be used for fault finding?

Many thanks.
 
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I've had good results using a smart phone app like PA Tone. I inject it into the AUX (or other input) using a 3.5mm to twin RCA and then trace the signal back from there. Also useful for generating tones when centering speaker cones for refoam :-)
 
You can go with KKmoon XR2206, HSMazalea High Precision Digital DDS, Kuman 24MHz Dual-channel DDS etc which are within your budget that works more efficiently.
 
I use my phone all the time (every day), "Test Tone Generator" app (no affiliation) and many other free options. Search your app "store" for "tone generators" and choose the one that works better for you. Some have stereo output with 2 different signals at the same time, some others allow custom freqs, some add different noise generators, and so. I think all of them have sine, triangle, sawtooth and square waves.
 
Bear in mind that the apps for smart phones and the like are only giving you audio frequencies. Fine if your simply signal tracing though an amp. The app I have for iPad does clean sinewave up to 20k. Square wave Is rough at 250hz and falls apart as you go up.
 
You need at least 2MHz square wave, able to adjust DC offset. This is very important for testing amps in the future if you get deeper into amps. The one I suggested is 25MHz.

You don't think audio frequency, a lot of the high quality amps has frequency response into 200KHz, the one I design is pushing 300KHz!!! It is important because you want very fast transient. More importantly is testing the slew rate and rise time of the amp. This show the transient response and predict THD. If the phone app cannot give you fast square wave, it's not going to cut it. I need to push slew rate of 35V/uS!!!!
 
Thanks to all for the advice, anyone know if the scope test tone could be used? I have tried a laptop with a tone generator program but the output is very fuzzy and has ghosting.
 
Sometimes the "ghost" is an oscilloscope setting not optimal. Make sure your "trigger" setting is matching the channel you measure. My phone has a very clean sinewave, suitable for tracing a signal.
 
Thanks Elnado, I have just tried the Test tone Ap on an old smart phone, It seems to work pretty well so that will do for me to learn with for now.
I will look out for something better for the future.

Many thanks.
 
grabread said:
Thanks Elnado, I have just tried the Test tone Ap on an old smart phone, It seems to work pretty well so that will do for me to learn with for now.
I will look out for something better for the future.

Many thanks.
Click to expand...
I'm doing the same, looking for something better for the near future...

I use the phone app to trace signals, adjust levels, meters, recording levels and bias level in tape machines and that kind of applications. It also gives a rough square wave, but useful for some tests.

I think my next step will be something like the units previously suggested (they are in the $50-60 range), up to 24 or 25MHz.
 
There's a couple of videos and tutorials out there, detailing the build of an audio signal probe that I mentioned above. I found it really useful for sniffing a signal through an amp. Here's one of the vids, shows exactly how it works.....

 
I think probe with an audio probe is redundant if you have a scope, It is exactly like using a scope to follow the signal around, you just buy one more piece of equipment.

Things that you won't see from audio probe is you cannot see clipping, other oscillation and noise. Scope is going to tell a lot more.

It might make sense to get an audio probe 30years ago as scope are very expensive. Now scopes are much cheaper and do so much more.
 
Alan0354 said:
I think probe with an audio probe is redundant if you have a scope, It is exactly like using a scope to follow the signal around, you just buy one more piece of equipment.

Things that you won't see from audio probe is you cannot see clipping, other oscillation and noise. Scope is going to tell a lot more.

It might make sense to get an audio probe 30years ago as scope are very expensive. Now scopes are much cheaper and do so much more.
Click to expand...

Absolutely agree Alan, however my scope is something else I have to learn how to use properly but my audio probe allowed me to quickly hunt a dropped signal and repair the amp. I will have to get to scope school real soon :)

A scope cannot be had for under a hundred bucks here either, so the probe made good economic sense too.
 
And now, an apology. I just realised I've been prattling on about an audio probe when in fact the OP wanted options on a signal gen.

The comments about the probe were intended for another thread and I got carried away cross-posting.

I will now go and take my medication :-)
 
Been there, done that. I once click the post above or below by accident and responded!!! People did not know what I was talking about.
 
there are some kits on ebay that are signal generators - they come in kit form and no instructions
but there are youtube videos that show how to solder/assemble. about $20 bucks.
 
I realize I already bought one of those kits !! Arrived from Hong Kong Yesterday !!! $13 approx.

Here is a pict. It's a multi component tester + signal generator ! I need to assemble and check its performance.

P1160029.jpg
 
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