Please Help With Audio Circuit Design

dreamer · Joined: Jan 30, 2013 Posts: 3 Location: U.S.A.

Hi,,,,I'm new here and love building electronic things....I'm no whiz at this electronic thingy like you guy's, so maybe someone could possibly please help me out..I have been searching the internet for days, trying to come up with a schematic or even some guidance on how to build this project ....Here's what I'm trying to build or achieve .....I have a device that has a line level audio output which operates on a single frequency of approximately 630 Hz,, I would like to run it into a circuit that would shift the audio frequency up and down a few hundred Hz either way, with the use of a potentiometer.... Also I would like the output to remain at a headphone level... Now the simpler the circuit the better plus the lower the current draw and voltage the better....I would greatly appreciate any schematics or ideas on this subject...Please email with any ideas or suggestions...Thanks in advance....Dreamer

forshee · Joined: Dec 16, 2010 Posts: 41 Location: Hopkins, MN

If you want a stable shift then you will need a really complicated analog circuit or a digital one. Frequency shifting is not an easy task you would be better off generating an oscillator that is controllable that generates your tone. Here is a link to the only analog frequency shifter I know. http://www.jhaible.de/fs1a/fs1a.html Pretty complex. And I'd do it with a DSP or FPGA which is not really a DIY friendly option.

Maybe if you give a description of what you want the output to be we can find a simpler method.

dreamer · Joined: Jan 30, 2013 Posts: 3 Location: U.S.A.

Hi,, hey thanks for taking the time to reply....I think you are right that circuit is way to complex for me....Is there any way you could direct to another circuit that's like the oscillator one that you described? Thanks again..Dreamer

forshee · Joined: Dec 16, 2010 Posts: 41 Location: Hopkins, MN

There are lots of options. Any VCO circuit would provide a lot of control but if you want simple I'd google 555 oscillators. You should find a bunch of simple circuits. This will be a squarewave so you may need a filter or wave shaper after it but there are plenty simple examples of those too if you don't need the more advanced functions of a voltage controlled filter. And then you might need a simple opamp amplifier to get you to your desired output level.

So in short, I'd suggest 555 ocillator > filter > amp. You should be able to google everything but I'd be happy to give you a few more pointers if you get stuck.

dreamer · Joined: Jan 30, 2013 Posts: 3 Location: U.S.A.

Hi,, Thanks for all of your help...I will check around and maybe do some sample bread boarding.....I did see some vco circuits but I don't think they will operate at my audio frequency...Perhaps I can change a few components to achieve my desired frequency....Thanks for your time and effort...Dreamer