small audio VCO

[Bob Stephens]

Anyone know of a small,low power, SMT, audio frequency voltage controlled
oscillator IC?
I'm trying to generate a swept sinewave from 100Hz to 10Khz driven from a
12 bit DAC. I've found a bunch of serial input types, but unfortunately I'm
out of I/O on this design - just one DAC remaining available.

TIA

Bob

 

[Bob Stephens]

On Wed, 03 Nov 2004 09:36:44 -0800, John Larkin wrote:

On Wed, 03 Nov 2004 17:22:37 GMT, Bob Stephens
stephensyomamadigital@earthlink.net> wrote:

Anyone know of a small,low power, SMT, audio frequency voltage controlled
oscillator IC?
I'm trying to generate a swept sinewave from 100Hz to 10Khz driven from a
12 bit DAC. I've found a bunch of serial input types, but unfortunately I'm
out of I/O on this design - just one DAC remaining available.

TIA

Bob

Could you talk to a serial-data DDS chip? They're almost perfect sine
generators.

I assume you don't have enough compute power to play a swept sine
directly on a DAC!

John

I looked at a couple of DDS chips. They'd be ideal except all the ones I
saw need serial data, serial clock, and an enable or latch of some sort - 3
I/O pins I don't have

And yes, I did try to generate a sine in software with a look up table,
phase accumulator etc. Not even.

Thanks for the reply


Bob

 

[martin griffith]

On Wed, 03 Nov 2004 17:22:37 GMT, in sci.electronics.design you wrote:

Anyone know of a small,low power, SMT, audio frequency voltage controlled
oscillator IC?
I'm trying to generate a swept sinewave from 100Hz to 10Khz driven from a
12 bit DAC. I've found a bunch of serial input types, but unfortunately I'm
out of I/O on this design - just one DAC remaining available.

TIA

Bob
max038 maybe

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1257



martin

Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.

 

[Jamie]

if you wanted to work with a PIC that has a DAC on it you could create a
wide range of output using a PCM method..
if your project is getting serious enough i think it would be worth
your while to invest in a Pic Programmers setup and you then could
write the simple code required to generate your Sine wave out that
would have nice smooth sine to it.
you can use one of the ADC inputs as a bias to set your output etc..


Bob Stephens wrote:

Anyone know of a small,low power, SMT, audio frequency voltage controlled
oscillator IC?
I'm trying to generate a swept sinewave from 100Hz to 10Khz driven from a
12 bit DAC. I've found a bunch of serial input types, but unfortunately I'm
out of I/O on this design - just one DAC remaining available.

TIA

Bob

 

[Bob Stephens]

On Wed, 03 Nov 2004 18:59:53 +0100, martin griffith wrote:

On Wed, 03 Nov 2004 17:22:37 GMT, in sci.electronics.design you wrote:

Anyone know of a small,low power, SMT, audio frequency voltage controlled
oscillator IC?
I'm trying to generate a swept sinewave from 100Hz to 10Khz driven from a
12 bit DAC. I've found a bunch of serial input types, but unfortunately I'm
out of I/O on this design - just one DAC remaining available.

TIA

Bob
max038 maybe
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1257



martin

Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.

I looked at that one. The killer there was the power consumption,
~ +/- 40 mA.

Thanks,


Bob

 

[Bob Stephens]

On Wed, 03 Nov 2004 13:21:45 -0800, Jamie wrote:

if you wanted to work with a PIC that has a DAC on it you could create a
wide range of output using a PCM method..
if your project is getting serious enough i think it would be worth
your while to invest in a Pic Programmers setup and you then could
write the simple code required to generate your Sine wave out that
would have nice smooth sine to it.
you can use one of the ADC inputs as a bias to set your output etc..

Not an option I'm afraid. This is a last minute feature for an existing

8051 based design. No room for another micro.


Thanks,

Bob