I need a signal (sine) generator (<10khz) to troubleshoot some of my audio designs on an oscilloscope. I bought XR2206 kit off of amazon ($10), and it works, but there are two fairly big problems with this adaptation:

1. The gain pot is backwards.
2. The gain doesn't go to zero, and it's pretty hot even when it's all the way down.

The schematic that came with it is not readable, I'm not sure I could modify it very easily (although I would if I knew what to do). So I started looking for something else.

I've read there are 3-4 basic ways to generate a function. XR2206, Max038, xr8038 and DDS. The FG-100 seems cheap enough for $25. Hackaday did a review, with mixed results.

I don't care if it's DIY or purchased, analog or digital, just looking for something that works for <$50. Just need a variable 10-10k frequency audio (sine) signal with variable gain. Suggestions?

 

This guy has tested a bunch of signal generators. Reading through all his reviews, there is one that he raves over: the OWON DGE1030. A little more than I wanted to spend. But for $100 on Amazon, seems like a great deal.

 

1. The gain pot is backwards.

so swap the sides of the pot, keep the wiper as is.

1. The gain doesn't go to zero, and it's pretty hot even when it's all the way down.

unfortunately to offer products like these dirt cheap, important parts are omitted. that includes things like buffer stage, attenuator...

you get what you pay for... if you want complete product, get something that is a complete product.

 

One external potentiometer can provide you with an adjustable output that can get as close to zero as you need. Mounting it may be a problem unless the signal-gen you bought is just a bare board. Repackaging products can often produce a more usable product.

 

One external potentiometer can provide you with an adjustable output that can get as close to zero as you need. Mounting it may be a problem unless the signal-gen you bought is just a bare board. Repackaging products can often produce a more usable product.

Could you describe how a pot could be used to attenuate it?

 

Could you describe how a pot could be used to attenuate it?

 

Post #6 includes a graphic depiction of what is described. It would take me a whole lot of words to adequately provide a description with that much detailed information. And some folks, unable or unwilling to visualize, would complain. bitterly.

Really, post #6 is EXCELLENT!!!

 

The only thing that Post#6 doesn't address is the Output-Impedance of the Oscillator-Circuit,
and the Input-Impedance of whatever device is being driven,
relative to the Resistance of the Pot.

In some cases it may not matter at all, in others, it may be very wonky and problematic.
.
.
.

 

The 1K pot seems like a good compromise. The output impedance of the generator is 600 ohms.

 

If I don’t have a 1k pot, I could assume it’s at 50%, and use a pair of 500 ohm resistors? Would that cut the volume in 1/2, for example?

 

YES, that would cut the voltage in half. So do you have a potentiometer of some other value on hand???

 

I have a A2k and C5k. Lowest linear pot is B10k. I could try the 2k and see if there’s a sweet spot, measure it and possibly modify the pcb with fixed values later.

 

So are you looking for a piece of test equipment or what? You want to scan through the frequencies so you can graph them? Sine wave generators are actually fairly cheap. I have bought several over the years that I have used and liked. Can you use a generator that generates one frequency at a time? Making an attenuation is actually very simple.

 

The application is for testing audio designs?????
My guess is that audio designs include attenuators, and often also different sorts of tone controls.

 

FWIW, any smartphone with the right free app can be used as a signal generator throughout the audio range. I use that for testing headphones and/or hearing. It's fun to make a tone at 13K to drive the kids nuts. The adults can't hear it

 

Iam fortunate enough to have an actual "audio frequency generator" , the only inconvenience is waiting for the tubes to warm up for it to deliver any signal.

 

It's fun to make a tone at 13K to drive the kids nuts. The adults can't hear it

oh I gotta try this!

 

oh I gotta try this!

On an iPhone, try Tone Gen

 

The Owon DGE1030 sine wave amplitude when adjusted less than 1Vpp the THD <0.2% over the audio range.
Single Channel, Lots of waveforms, modulation types, sweep ect. 14bit vertical resolution means nice smooth waves.
30ppm good frequency accurracy. The pc software and interface good. attractive display.
The Owon DGE2035 same has two channels. FeelTech has been popular also.

 

On an iPhone, try Tone Gen

ok just downloaded it.
I’m 51. My hearing tops out around 15.5 kHz. Is that normal?

My teenagers top out at 17k.