tone generator for testing circuits

[ulysses]

hi all,

im looking for a simple tone generator to generate a sine wave or similar wave (maybe adjustable), maybe with variable pitch, and volume output the same volume as a guitar pickup

something simple to stick on the workbench mainly using as a probe to test points of various circuits

im looking for something simple -- is there a circuit you love to use? one that fits this description?

cheers, ulysses

[temol]

Hi,

I'm using this device

T.

[Fancy Lime]

Γεια Ὀδυσσεύς,

I like to use the good old phase shift oscillator for this kind of thing. There are many ways of implementing it, I usually go with the simplest form, the single transistor one, using some high gain NPN, like 2N5088, 2N5089, MPSA18, MPSA13 (darlington), but almost any transistor should work, relly. Look ye here:
https://en.wikipedia.org/wiki/Phase-shift_oscillator
and here:
https://www.electronics-tutorials.ws/oscillator/rc_oscillator.html
for the principle explanation. A good starting point for design is the old phozer by runoffgroove:
http://www.runoffgroove.com/old-phozer.png
The stuff in the lower left corner is what you are after. The "Depth" control whiper becomes your output (just stick a DC blocking cap at the end) and that pot then also serves as the volume control. You will have to set that to "guitar like level" by ear to fit your guitar. If you want to get audio frequencies from this design, change the three 1µF caps to something like 22n-100n. Try what works best, they don't all have to be the same.

The output is not a perfect sine wave but close enough.

Cheers,
Andy

[cab42]

I use RG's Quick and Dirty oscillator.

Simple and easy.

[Sooner Boomer]

I've got two things I use.  The first is an old circuit design using an Exar XR-2206.  I bought a kit from Jameco because I'm lazy, and because it has everything but a case and knobs.  The chip can do modulation/sweep, so I'm (still) looking for an LFO to do this.

The other thing I use is an app for my tablet.  It can do two independent channels, sine, triangle, and square wave; fixed frequency as well as sweep.  Running this on a cheep, used cell phone, it can cost under $20.

I've also found a decent o-scope app.

[tristanc]

I'm using this device

Highly recommend this circuit. End up using it all the time along with the Burst Generator.

I've a couple of PCBs for it should that be of interest: https://www.diystompboxes.com/smfforum/index.php?topic=122355.0

Failing that, check ebay for an old Thandar TG102. Does loads more and can be found cheaply.

T

[DIY Bass]

I have one of these https://www.ebay.com.au/itm/DDS-Function-Signal-Generator-Sine-Square-Triangle-Sawtooth-Wave-Low-Frequency-/303048326366?hash=item468f167cde  I had one without the casing and it did not last long.  I think I accidentally shorted something out just putting it down on the bench. It still works fine as far as the microcontroller goes, but there is no output.  One day I might try and repair it.

I also have used my phone with an app. 

[Fancy Lime]

Wasn't "simple" one of the requirements?

[FiveseveN]

I use my phone and this: https://play.google.com/store/apps/details?id=com.julian.apps.SoundForm&hl=en and there are a bunch of similar apps.

[DIY Bass]

Wasn't "simple" one of the requirements?

Is simple simple to build, simple to use, simple to understand the circuit or limited in function?  all those things could be simple.  A complex one can still be simple to use

[deadastronaut]

i bought one of these....for a quid you cant moan...

saves me strumming whilst troubleshooting.

https://www.ebay.co.uk/itm/NE555-Waveform-Generator-Suite-Multi-channel-Sine-Triangle-Square-Wave-Kit-hot-/202038825826?hash=item2f0a73d362


hook up a 9v batt, and a jack...sorted.

[Fancy Lime]

Wasn't "simple" one of the requirements?

Is simple simple to build, simple to use, simple to understand the circuit or limited in function?  all those things could be simple.  A complex one can still be simple to use

Well it would be rather difficult to conceive of a monophonic sine wave generator that would *not* be simple to use, woudn't it? In this case I too "simple" to mean "simple to build", since the OP probably wants to DIY it (this being DIYstompboxes.com, and all). "Simple to understand" and "limited function" tend to correlate with simple to build anyway.

Andy

[ulysses]

thanks all for your replies. some great ideas there.

cheers

[merlinb]

This is simple in most ways, and does more than you asked for:
http://electronics-diy.com/electronic_schematic.php?id=822

[diydave]

Mp3 player with:
- 1 minute sinus 1kHz
- 1 minute pink noise
- 1 minute white noise
- ...

The same 3 files on my laptop.
headset out --> circuit under test --> mic in
Running xoscope, I even have an oscilloscope

[merlinb]

I was recently reminded of this cute circuit for creating sine waves very cheapely:

[Digital Larry]

I'm in the mobile app camp recently.  Another thing that's probably useful is something that can make tone bursts.  I'm starting to prepare for my second ever Hammond tube amp to guitar amp conversion and I really don't know much about tubes.  Sine wave shows you were the distortion occurs.  Square wave gives you an overall feeling for circuit frequency response if you keep it away from distortion.  Tone burst will show you how well the power supply handles transients.