simple tone generator

[12vdc]

would like to generate 10hz to 80hz 500 mv output to test woofers (with an amp)
Looking for a simple circuit.

 

[KrisBlueNZ]

Simplest option: create a .WAV file with a waveform editor such as Audacity and download it onto a smartphone or an iPad.

Edit: I meant iPod, not iPad!

 

[12vdc]

well, I don't know where you are from but those of us living in 1980 only have a soldering iron, solder (the real stuff with lead) and a bag of caps and resistors. My phone has a dial on it and ..... I want a small prject box with a power switch and a pot to vary the freq.

 

[davenn]

well, I don't know where you are from but those of us living in 1980 only have a soldering iron,

We are from the rest of the world where even in 3rd world countries, everyone has a cellphone

so you are telling me Canada is worse than 3rd world ? surely you jest

Dave

 

[KrisBlueNZ]

I want a small prject box with a power switch and a pot to vary the freq.

OK. Ironically, that makes things more difficult! In that case, your simplest option would be an XR2206. They're no longer manufactured, but you can get them on eBay. You can also get kits based on them.

 

[hevans1944]

If you are "testing" woofers, you probably want a nice sinusoidal output with almost zero harmonic distortion and good amplitude stability as a function of frequency. What you need is a Wien bridge oscillator, said bridge having been developed by Max Wien in 1891. If you can find one, the Hewlett-Packard 200CD audio signal generator is an excellent choice. Or, if you want to roll your own, I have attached the original schematic from William Hewlett's 1939 U.S. Patent. If you can find the parts you need (a dual-ganged capacitor or dual-ganged resistors) the Wien bridge oscillator is simple to build... oh, you will also need a small incandescent light bulb whose filament is used to provide negative feedback for amplitude stability.

If you follow the "roll your own" link above, Ramon describes a 1 kHz to 10 kHz oscillator. It will take some design effort to lower the range to 10 Hz to 100 Hz (probably need two incandescent lamps wired in series), but his circuit only uses one potentiometer and NO variable capacitors.

 

[12vdc]

Hmmm....the Wien Bridge is interesting (thanks for link) I was hoping for something less complicated (intimidating). Looks like a cheap mp3 player and some tone files is the easiest.

 

[LvW]

12vdc - in case you are interested in linear (harmonic) oscillators I would not recommend to restrict yourself from the beginning to the WIEN type oscillator only. There are many other oscillator topologies which could meet your requirements. This applies, in particular, to the tuning capabilities which are not so comfortable for WIEN oscillators (dual gang pots necessary).