sine wave generator with dc offset and amplitude..

[TechGuy]

Hi

Does anyone know how to generate a low frequency sine wave around 150Hz with amplitude and dc offset control..?
many thanks

 

[crutschow]

Generate the sinewave with an op amp bubba or phase-shift oscillator. Run that signal through a summing op amp circuit with the other input being a DC voltage. Use pots for both inputs to independently adjust the amplitude and offset.

 

[ahsan_i_h]

You can use waveform generator ic ICL8038 to generate the sinewave. For amplitude and dc offset control you may need opamps.

Datasheet: https://web.mit.edu/6.331/www/icl8038data.pdf

 

[Audioguru]

You can use waveform generator ic ICL8038 to generate the sinewave. For amplitude and dc offset control you may need opamps.

Datasheet: https://web.mit.edu/6.331/www/icl8038data.pdf

The Intersil ICL8038 is obsolete and has not been made for many years. I used it in 1975 (39 years ago).
The Exar XR2206 was similar but is also obsolete.

Some people hoarded them when they were available and now are selling them at high prices. A Chinese company is also selling (making?) them today.

 

[crutschow]

What's the highest output voltage you need?

What are you supply voltage(s)?

 

[D.A.(Tony)Stewart]

How about a PC signal generator like Audacity (free) or Cool Edit Pro2 or DJpro and external amplifier.
Or for Linux http://www.comp.leeds.ac.uk/jj/linux/siggen.html

 

[crutschow]

Below is a simulation of a phase-shift oscillator that may work for you. U5 adjusts the amplitude and U6 independently adjusts the output DC offset. It uses one quad op amp plus associated resistors and caps. A phase-shift oscillator has the advantage of averaging the time-constants that determine the oscillation frequency over three sets of resistors and capacitors, reducing the effect of component tolerances (assuming the tolerances are a Gaussian normal distribution).

 

[TechGuy]

hi, Output should be 5.5V PP and and possibly from a single supply voltage.
Cheers

-----

Thanks mate, but I need it hardware!

How about a PC signal generator like Audacity (free) or Cool Edit Pro2 or DJpro and external amplifier.
Or for Linux http://www.comp.leeds.ac.uk/jj/linux/siggen.html

----

Generate the sinewave with an op amp bubba or phase-shift oscillator. Run that signal through a summing op amp circuit with the other input being a DC voltage. Use pots for both inputs to independently adjust the amplitude and offset.

After carrying out a search I think I'm going with your advise it seems fairly easy.

Cheers

 

[schmitt trigger]

The Intersil ICL8038 is obsolete and has not been made for many years. I used it in 1975 (39 years ago).
The Exar XR2206 was similar but is also obsolete.

Cutting my teeth in electronics in the late 70s, I remember the XR2206 with particular fondness.
It allowed me to build a low cost function generator, to be used on my home lab.

It is unfortunate that it became obsolete, as it is a great learning tool for beginners.

But large companies can't live from hobbyist sales alone. Nowadays, most if not all signal generators are digitally synthetized, and analog solutions like the XR2206 lost its OEM share.

 

[crutschow]

..........................
After carrying out a search I think I'm going with your advise it seems fairly easy.

Note that you need to add decoupling capacitors on the power rails which I didn't show. 0.1uF ceramics from each rail to ground should suffice.

To improve the resolution of the offset pot (U6) add a 5k ohm resistor in series with each end to the pot to the rails. Also change R6 and R8 to 50k ohm.

 

[TechGuy]

Note that you need to add decoupling capacitors on the power rails which I didn't show. 0.1uF ceramics from each rail to ground should suffice.

To improve the resolution of the offset pot (U6) add a 5k ohm resistor in series with each end to the pot to the rails. Also change R6 and R8 to 50k ohm.

Thank you mate, will do! I'll let you know how I go.