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Analog sine wave generator? (0v-5v)? Answered

I am wondering how to create an analog (NOT digital) sine wave from 0 - +5 volts (Not -5 - +5). If you could, post a schematics diagram, or send a link to a page with the schematics. It has to have a variable pitch.


Most trivial oscillators take just a +v and ground input, and produce output which covers a range somewhere between the two (probably not quite going to the extremes, to avoid transistor saturation effects). So if you look at any example design that's working off 5V or 6V input, that will probably come close to doing what you need.

If you want _exactly_ a 5V peak-to-peak signal, you'll either want an oscillator with adjustable output or a final adjustable amplifier stage.

If your signal is going negative relative to ground, you've hooked up the wrong reference as ground, and/or you're using a DC blocking capacitor or otherwise subtracting a constant 2.5VDC from the sine wave. If you're getting 10V peak-to-peak, you're either generating too hot a signal or you're amplifying it too much.

i have no idea what your talking about with this "5volt peak to peak" stuff, all i want is 0v at the bottom of the wave, and five volts at the top, just like i drew.

My point is that 0V is an arbitrary point. The same sine wave can be described as 0v to 5V, or -2.5V to +2.5V, or -5V to 0V, or -1 to +4, or anything else depending on what you consider the ground reference voltage.

So this is really a matter of how you connect things. As Sean explains, if your oscillator internally thinks about that as -2.5 to +2.5, add a +2.5V DC component to its output to correct that -- which may be as simple as choosing how you connect the oscillator to the rest of the circuit

i want it to look excatly as i drew in the picture, 0 volts at the bottom, and five volts at ther top, so the sine wave will be "sitting" on the middle line of the oscilloscope.

Adding a 2.5V DC offset will produce exactly that.

Create a sine wave using any of the many standard methods, be it by a waveshaper integrated circuit like the 8038, a digital synth chip, any of many opamp feedback oscillators, or "discrete" digital shapers.

The advantage of the last one is that you can make a 0-5 V ~sine directly, with only 5V power and a clock input (or fixed 555 clock or similar)

So....the dirty trick is this: Take a bipolar sine wave and feed it through an adjustable offset circuit that adds 1/2 of the voltage difference between the bottom and the top.

Sine waves are by their nature considered to be bipolar, ie, they travel from +1/2 their height to -1/2 their height, following a sinusoidal equation of motion from -1 to +1 and back. They also may have a DC component, or offset.

For a 0-5V sine wave, you have to ADD 1/2*5V of DC voltage to a +/- 2.5VAC sinusoid.

A simple SUMMING AMPLIFIER opamp design that employs
  • a handful of resistors
  • a blocking cap for the AC input,
  • a timmer or two
  • an inexpensive general purpose opamp
can do this for you if you only have an AC source like an MP3 player for the sine wave (for instance, a looped MP3 file, playing the note A-442, etc.)

Easiest way ? See my previous reply on the XR8038

If you want a really pure sine, look at Wein bridge oscillators - they'll give you offset outputs.

Why the hangup on using -ve supplies ? Its the best way, when you can.