Square wave oscillator help please.

Guest
Hello,

Can anyone help me change this LM386 1kHz square wave oscillator to
40kHz? Formulas or a walk through?
PDF Page 5 http://www.national.com/pf/LM/LM386.html

There's nothing that I can find in the PDF to help me and searching
has found mainly square wave or amplifier kitsets.

Regards,

Andrew.
 
Rubicon wrote:
Hello,

Can anyone help me change this LM386 1kHz square wave oscillator to
40kHz? Formulas or a walk through?
PDF Page 5 http://www.national.com/pf/LM/LM386.html

There's nothing that I can find in the PDF to help me and searching
has found mainly square wave or amplifier kitsets.

Regards,

Andrew.
Click to expand...
Sorry, I cant find any reference to a square wave oscillator on this
page.
--
John Popelish
 
On Sat, 24 Jul 2004 21:27:33 -0400, John Popelish <jpopelish@rica.net> wrote:

Sorry, I cant find any reference to a square wave oscillator on this
page.
Click to expand...
If you download the datasheet in PDF form, then it's in the bottom right corner
on page 5 of the amplifier datasheet.

Jon
 
Jonathan Kirwan wrote:
On Sat, 24 Jul 2004 21:27:33 -0400, John Popelish <jpopelish@rica.net> wrote:

Sorry, I cant find any reference to a square wave oscillator on this
page.

If you download the datasheet in PDF form, then it's in the bottom right corner
on page 5 of the amplifier datasheet.

Jon
Click to expand...
Thank you. Adjust the size of the capacitors by 1/40.

--
John Popelish
 
John Popelish <jpopelish@rica.net> wrote in message news:<41030C85.390A5410@rica.net>...
Rubicon wrote:

Sorry, I cant find any reference to a square wave oscillator on this
page.
Click to expand...
It's on the datasheet (page 5) http://www.national.com/ds/LM/LM386.pdf

Best regards,
AM
 
(Rubicon) wrote in message news:<41040a4b.676269@news.netaccess.co.nz>...
Hello,

Can anyone help me change this LM386 1kHz square wave oscillator to
40kHz? Formulas or a walk through?
PDF Page 5 http://www.national.com/pf/LM/LM386.html

There's nothing that I can find in the PDF to help me and searching
has found mainly square wave or amplifier kitsets.

Regards,

Andrew.
Click to expand...
You are probably looking for this, time period of square waves is

T=2*RC*In((2R1 + R2)/R2)

Where in the original schematic
R=30k, C=.1u, R1=1k and R2=10k

Adjust these values which suit you the best.

Best regards,
AM
 
On Sun, 25 Jul 2004 00:37:18 -0400, John Popelish <jpopelish@rica.net>
wrote:

Jonathan Kirwan wrote:

On Sat, 24 Jul 2004 21:27:33 -0400, John Popelish <jpopelish@rica.net> wrote:

Sorry, I cant find any reference to a square wave oscillator on this
page.

If you download the datasheet in PDF form, then it's in the bottom right corner
on page 5 of the amplifier datasheet.

Jon

Thank you. Adjust the size of the capacitors by 1/40.

--
John Popelish
Click to expand...
Thankyou for the help.

I apologise for not being specific enough, it's something I must
attend to.

Regards,

Andrew.
 
So:

0.1uf / 40 = 0.0025uF
50uF / 40 = 1.25uF

Both non standard values in my catalogues. Time to work out parallel
caps?

0.0015uF + 0.001uF = 0.0025uF
1uF + 0.15uF + 0.1uF = 1.25uF

I thought the LM386 might make a better ultrasonic transducer driver
than the 555 astable circuit I have but it seems a little messy in
comparason.

Regards,

Andrew.




On Mon, 26 Jul 2004 01:49:18 GMT, (Rubicon) wrote:

On Sun, 25 Jul 2004 00:37:18 -0400, John Popelish <jpopelish@rica.net
wrote:

Jonathan Kirwan wrote:

On Sat, 24 Jul 2004 21:27:33 -0400, John Popelish <jpopelish@rica.net> wrote:

Sorry, I cant find any reference to a square wave oscillator on this
page.

If you download the datasheet in PDF form, then it's in the bottom right corner
on page 5 of the amplifier datasheet.

Jon

Thank you. Adjust the size of the capacitors by 1/40.

--
John Popelish

Thankyou for the help.

I apologise for not being specific enough, it's something I must
attend to.

Regards,

Andrew.
Click to expand...
 
Thanks.

Though mathematics was never my strong suit I can work through that
formula with the 1kHz/circuit values example to start with.

Andrew.

On 25 Jul 2004 00:35:13 -0700, animesh_m@eudoramail.com (Animesh
Maurya) wrote:

(Rubicon) wrote in message news:<41040a4b.676269@news.netaccess.co.nz>...
Hello,

Can anyone help me change this LM386 1kHz square wave oscillator to
40kHz? Formulas or a walk through?
PDF Page 5 http://www.national.com/pf/LM/LM386.html

There's nothing that I can find in the PDF to help me and searching
has found mainly square wave or amplifier kitsets.

Regards,

Andrew.

You are probably looking for this, time period of square waves is

T=2*RC*In((2R1 + R2)/R2)

Where in the original schematic
R=30k, C=.1u, R1=1k and R2=10k

Adjust these values which suit you the best.

Best regards,
AM
Click to expand...
 
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