Schematics needed for 3V 1KHz Sine wave generator

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I think that your are not getting replies because the question is so open ended. I would ask -- do you really only want only one frequency? What is the desired output level and into what impeadance? Does it need to be a spectrally clean signal? Does it need to be frequency stable and accurate? The first thing that comes to mind is a one transistor LC based oscillator perhaps with a buffer. Of course the physical size of the L and C are going to make it hard to get into any of those boxes. The other approach if you need accurate frequency is to run a crystal oscillator at some higher frequency and then divide it down, but that involves a flip flop or some such which sill output a square wave and then you could filter out the harmonics,. I would consider a small microprocessor like a PIC. There are probally some that could be programed to do the frequency division with onboard logic. All of these options can be designed to operate off of your 3V, but you have 5V when connected to USB. Do you mean that this should be able to operate stand alone after charging? In short, tell us more about what your are trying to acconplish. I must be bored to write a reply like this.
 
Yes, I only need the one frequency, 1KHz. It is for a tone test on induction loop equipment. We've tried using an MP3 player but the conversion from the test CD changes the tone so it is not an accurate reproduction of the 1KHz tone. I have used my iphone but I really don't want to lend that out, plus the output is not quite high enough before distortion kick in. My thought was to have a tone generator that could easily be recharged through USB. When it's charged, it could be taken to the site for test. I could be easy on myself and build a 9v tone generator, but what's the fun in that.:D

I have already been to Mr Elliot's pages.
I Will look into Simon7000's links, thank you.
 
if you're fixated on hacking analog, fine - but the DAP will be easier

I'd be suprised if mp3 really botched a single sine

but even if that's true you can still play .wav/flac on some players, even more if you include those you can RockBox

if you need a little more V then Radio Shack has audio isolation xfmr that can be wired for 2x (auto xmfr mode)
 
Last edited:
I don't see big problems -80 dB spurs are pretty good compared to what a "simple" analog sine oscillator will do

no way you're going to get the narrow linewidth even a poor xtal in a cheap DAP will give



I created a 1 kHz sine in Ltspice - exported with the .wave function

used foobar2000, lame 3.99.2, encoded as mp3 v2,

reconconverted to .wav - back in to Ltspice

below is a 1048576 point fft of 10 seconds 1kHz sine > 16/44.1 .wav > mp3 v2 > .wav
 

Attachments

  • mp3_sine.PNG
    mp3_sine.PNG
    50.7 KB · Views: 410
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.