Variable LFO

[Ron M.]

On Wednesday, October 22, 2014 1:13:42 PM UTC-5, Ron M. wrote:

On Wednesday, October 22, 2014 12:00:10 AM UTC-5, d...@yipee.com wrote:
A Stanford paper called "Doppler Simulation and the Leslie"

https://ccrma.stanford.edu/~jos/doppler/doppler.pdf

Thanks and WOW!! CCRMA. Now that's a oldy but goody. Had an old CD produced by them way back in the 80's called the Digital Domain that was really cool. It was made specifically to show the benefits of digital audio. Some of the cuts on it were planes landing that really pushed the dynamic range to the max for the CD standard. Also some of them were just plain weird. They also included a version of deep note that would blow speaker cones right out of the basket.





On Tue, 21 Oct 2014 10:13:42 -0700 (PDT), "Ron M."

strmbrgr2@hotmail.com> wrote:



Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.

Also as a side story. Back in the mid 80's I worked with USDOS in VA near DC. Made a trip to CA for a secretary of state visit to set up two way comms.. This was when George Schultz was SOS. Security detail was using office on 2nd floor of this rickety old garage on the residential section of Stanford behind his house. The whole crew had left for a train trip to LA and they had no one to call DC to indicate they had departed. I was elected to perform that function. While waiting there was a small earthquake (my first). Old garage shook and settled and I swallowed my heart. Ahhh the memories. Had I remembered CCRMA I probably would have been able to visit them. Kick my self every time I think of it.

 

[Ron M.]

On Thursday, October 23, 2014 10:53:12 AM UTC-5, Michael Terrell wrote:

Michael Black wrote:

On Thu, 23 Oct 2014, Michael A. Terrell wrote:


"Ron M." wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.


There was a project to build an electroninc Leslie in a magazine in
the '70s. I think it was Popular Electronics but I no longer have my
collection. It was also sold as a kit. I assemebled a couple for
someone who couldn't solder very well. It might have been one of Don
Lancaster's designs, he had a lot of them published back then.

I think it wsa 1971, and I was thinking about that article, but can't
remember what was involved. I think that one was more likely from John
Simonton, of PAIA fame, if it was from one of the top tier writers.

Michael


PAIA is correct. March 1971, starting on page 51 and it was designed
by John S. Simonton, Jr.

Briefly spoke with him via email back in 2000 on an unrelated issue.

www.americanradiohistory.com/Archive-Poptronics/70s/1971/Poptronics-1971-03.pdf


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

 

[RobertMacy]

On Thu, 23 Oct 2014 05:47:38 -0700, Bob Masta <N0Spam@daqarta.com> wrote:

...snip...

The problem with the stepped sine would be that when you
stepped it slowly to get low frequencies, you would hear
each step.

Best regards,


Bob Masta
DAQARTA v7.60
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusiq generator
Science with your sound card!

Hi, Bob. How many of your Daarta LCR Meter's using soundcard do you have
out and about the world now? Didn't see it this signature block.

BACK TO THE SUBJECT:
Back in the 70's there used to be a single chip, very, very cheap,
solution to digitizing sound. The same chip performed ADC AND DAC! It had
a weird burst of plus/minus going into it, called CSVD something to do
with Continuous Slope Variable Delta, or Delay or something. Can't
remember. After straighforward digitization came along, lost site of that
thing. Used to be in those digitizing phones.

THAT chip was cheap!! easy to use and would provide a continuous waveform
output just by the nature of the device's techniques.

Again from memory, The chip was like a little constant v(t) where if you
put in +/- constantly you got no change to the 'trajectory' of the output.
The output was like herding cats. nothing in produced constant whatever
that was going on output. The data going to the chip looked frenetic at
the plus minuspeaks of the sine wave and had litt data during the high
speed [relatively straight lines] during crossovers. Also, from memory the
distortion was not too bad.

To digitize you used the chip in the ffedback and a comparator to get the
sequence of bits, or such.

 

[Michael Black]

On Thu, 23 Oct 2014, Michael A. Terrell wrote:

"Ron M." wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.


There was a project to build an electroninc Leslie in a magazine in
the '70s. I think it was Popular Electronics but I no longer have my
collection. It was also sold as a kit. I assemebled a couple for
someone who couldn't solder very well. It might have been one of Don
Lancaster's designs, he had a lot of them published back then.

I think it wsa 1971, and I was thinking about that article, but can't
remember what was involved. I think that one was more likely from John
Simonton, of PAIA fame, if it was from one of the top tier writers.

Michael

 

[Michael A. Terrell]

Michael Black wrote:

On Thu, 23 Oct 2014, Michael A. Terrell wrote:


"Ron M." wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.


There was a project to build an electroninc Leslie in a magazine in
the '70s. I think it was Popular Electronics but I no longer have my
collection. It was also sold as a kit. I assemebled a couple for
someone who couldn't solder very well. It might have been one of Don
Lancaster's designs, he had a lot of them published back then.

I think it wsa 1971, and I was thinking about that article, but can't
remember what was involved. I think that one was more likely from John
Simonton, of PAIA fame, if it was from one of the top tier writers.

Michael

PAIA is correct. March 1971, starting on page 51 and it was designed
by John S. Simonton, Jr.


<www.americanradiohistory.com/Archive-Poptronics/70s/1971/Poptronics-1971-03.pdf>


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

 

[Michael Black]

On Thu, 23 Oct 2014, Michael A. Terrell wrote:

Michael Black wrote:

On Thu, 23 Oct 2014, Michael A. Terrell wrote:


"Ron M." wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.


There was a project to build an electroninc Leslie in a magazine in
the '70s. I think it was Popular Electronics but I no longer have my
collection. It was also sold as a kit. I assemebled a couple for
someone who couldn't solder very well. It might have been one of Don
Lancaster's designs, he had a lot of them published back then.

I think it wsa 1971, and I was thinking about that article, but can't
remember what was involved. I think that one was more likely from John
Simonton, of PAIA fame, if it was from one of the top tier writers.

Michael


PAIA is correct. March 1971, starting on page 51 and it was designed
by John S. Simonton, Jr.


www.americanradiohistory.com/Archive-Poptronics/70s/1971/Poptronics-1971-03.pdf

My guess would have been April, so when I downloaded that issue and it
wasn't there, I kept downloading subsequent issues. March seemed a tad
early, it was only the second issue of Popular Electronics I bought.

Michael

 

[RobertMacy]

On Thu, 23 Oct 2014 08:52:59 -0700, Michael A. Terrell
<mike.terrell@earthlink.net> wrote:

...snip...

www.americanradiohistory.com/Archive-Poptronics/70s/1971/Poptronics-1971-03.pdf

<http://www.americanradiohistory.com/Archive-Poptronics/70s/1971/Poptronics-1971-03.pdf>

 

[Maynard A. Philbrook Jr.]

In article <742850cf-d303-4622-963a-ebe2ef3a1a8b@googlegroups.com>,
gherold@teachspin.com says...

On Wednesday, October 22, 2014 2:08:54 PM UTC-4, Ron M. wrote:
On Wednesday, October 22, 2014 11:07:38 AM UTC-5, George Herold wrote:
On Tuesday, October 21, 2014 1:13:42 PM UTC-4, Ron M. wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.



I've done a Wien bridge down to 3 Hz.

https://www.dropbox.com/s/lmso5zx69g2l1lc/DSCF0047.JPG?dl=0

You could push it to 1 Hz (maybe)



Or a stepped sine thing with square wave into a CD4017 and artfully chosen resistors on the output... into an opamp summer.



Could it be a triangle wave?

Upon researching it further it appears that a triangle would probably in fact work close enough to be unnoticeable. I might have over analyzed it. Does make the design a whole lot easier. The ramp up also might be a little over kill. Went to an old friend who works on Hammonds and has a Leslie corrected me on that. It appears they have either off, slow and high speeds and the ramp up is purely a mechanical lag which I have determined is way more difficult to implement
per some of the responses received. Thanks for all the help guys. Will let ya'll know what happens.



George H.

Yeah, compared to a sine a triangle is dead easy.
A current into a cap, with something that changes current direction at the limits... Heck might as well use a 555, where is John F.?

George H.

If you make a voltage divider that a pair of diodes can be attached to,
those diodes can then suppress the output of the timer via
a resistor to form a near sine wave on both ends.

Then it can be cleaned up a little..

That will give you the best results for the lowest price with
a broad freq sweep.

Jamie

 

Another quick thought. Try a beat frequency. Have 2 oscillators, 1
fixed at say 40Hz. The other variable from 40 to 45 hz. Mix them
together and you will end up with an output freq. of 1 to 5Hz.
Remember, the beat frequency is the difference of the 2 components. (
1 Hz and 40 Hz yields 1 Hz)

On Tue, 21 Oct 2014 10:13:42 -0700 (PDT), "Ron M."
<strmbrgr2@hotmail.com> wrote:

>Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.

 

Sorry. I mean 40 Hz and 41 Hz yields 1 Hz.

On Tue, 28 Oct 2014 10:44:53 -0700, doh@yipee.com wrote:

Another quick thought. Try a beat frequency. Have 2 oscillators, 1
fixed at say 40Hz. The other variable from 40 to 45 hz. Mix them
together and you will end up with an output freq. of 1 to 5Hz.
Remember, the beat frequency is the difference of the 2 components. (
1 Hz and 40 Hz yields 1 Hz)

On Tue, 21 Oct 2014 10:13:42 -0700 (PDT), "Ron M."
strmbrgr2@hotmail.com> wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.

 

The only problem you really have is the zero Hertz. Just use a switch, and a circuit just like an old guitar amp. Take the tremolo circuit, perhaps extend its range a bit, scale down the voltages and use an FET.

I found some decent regular old style depletion mode FETs at Digikey. I think this would be an excellent use for them, PLUS using them to manipulate the phases or whatevcer from your crossover, or whatever is going to actually create the effect.

The voltages canbe lower, the RC time ocnstants are almost totally immuine to other shit.

I guess you could use a MOSFET as well, but the old JFET would be more fun, and probably in line with your whole idea. The JFET is essentially a triode.

 

[Michael A. Terrell]

doh@yipee.com wrote:

Sorry. I mean 40 Hz and 41 Hz yields 1 Hz.

On Tue, 28 Oct 2014 10:44:53 -0700, doh@yipee.com wrote:

Another quick thought. Try a beat frequency. Have 2 oscillators, 1
fixed at say 40Hz. The other variable from 40 to 45 hz. Mix them
together and you will end up with an output freq. of 1 to 5Hz.
Remember, the beat frequency is the difference of the 2 components. (
1 Hz and 40 Hz yields 1 Hz)

On Tue, 21 Oct 2014 10:13:42 -0700 (PDT), "Ron M."
strmbrgr2@hotmail.com> wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.

What kind of mixer are you going to use?


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

 

[Michael Black]

On Wed, 29 Oct 2014, Michael A. Terrell wrote:

doh@yipee.com wrote:

Sorry. I mean 40 Hz and 41 Hz yields 1 Hz.

On Tue, 28 Oct 2014 10:44:53 -0700, doh@yipee.com wrote:

Another quick thought. Try a beat frequency. Have 2 oscillators, 1
fixed at say 40Hz. The other variable from 40 to 45 hz. Mix them
together and you will end up with an output freq. of 1 to 5Hz.
Remember, the beat frequency is the difference of the 2 components. (
1 Hz and 40 Hz yields 1 Hz)

On Tue, 21 Oct 2014 10:13:42 -0700 (PDT), "Ron M."
strmbrgr2@hotmail.com> wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.


What kind of mixer are you going to use?

Certainly a balanced mixer, and certainly in electronic music circles they
do know about the phasing method to get rid of the unwanted sidebands.
For single frequency tones, that's all relatively easily done, since you
can use methods to generate sinewaves that also have an output 90degrees
from the main one. So you get two of those, and two balanced mixers, and
you get your sum or difference very easily. It's when you need to mix
voice or really complex signals that the phasing method can be limited.

Michael

 

[Michael A. Terrell]

Michael Black wrote:

On Wed, 29 Oct 2014, Michael A. Terrell wrote:


doh@yipee.com wrote:

Sorry. I mean 40 Hz and 41 Hz yields 1 Hz.

On Tue, 28 Oct 2014 10:44:53 -0700, doh@yipee.com wrote:

Another quick thought. Try a beat frequency. Have 2 oscillators, 1
fixed at say 40Hz. The other variable from 40 to 45 hz. Mix them
together and you will end up with an output freq. of 1 to 5Hz.
Remember, the beat frequency is the difference of the 2 components. (
1 Hz and 40 Hz yields 1 Hz)

On Tue, 21 Oct 2014 10:13:42 -0700 (PDT), "Ron M."
strmbrgr2@hotmail.com> wrote:

Have a request of the gurus in here. I have needs for a relatively cheap OSC (sine) that can be varied from zero to approx. maybe 20 cycles continuously. Been busting my brain to implement it. This is for a source into a keyboard to act as a Leslie. Any ideas guys. THANKS.


What kind of mixer are you going to use?

Certainly a balanced mixer, and certainly in electronic music circles they
do know about the phasing method to get rid of the unwanted sidebands.
For single frequency tones, that's all relatively easily done, since you
can use methods to generate sinewaves that also have an output 90degrees
from the main one. So you get two of those, and two balanced mixers, and
you get your sum or difference very easily. It's when you need to mix
voice or really complex signals that the phasing method can be limited.

Michael

DDS would be a lot simpler, and the output level wouldn't change with
frequency.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.