Apply Random Low Frequency Phase Shift to Sine Wave

We make a couple of programmable resistors

but I can't tell you how they work, except that it's hard.

--

John Larkin   Highland Technology, Inc   trk 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Some of the old TI/BB stuff is ten times that price.

I wonder why Analog is about the only active maker of analog multipliers and DDS chips.

At 10 Hz, you could also do PWM/duty cycle multiplication. That can be very accurate. But if the goal is to randomize phase, it wouldn't need to be very accurate.

Hmmm, what use is

I*x + Q(1-x)

?

--

John Larkin   Highland Technology, Inc   trk 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

The error in that expression is linear rather than quadratic.

Cheers

Phil Hobbs

On a sunny day (Fri, 27 Oct 2017 14:59:26 -0700) it happened John Larkin wrote in :

5 Ohm is low for a CMOS switch chips, could be relays, or maybe home-made MOSFET sitches, uses DC-DC converters obviously.

On a sunny day (Fri, 27 Oct 2017 12:07:25 -0700 (PDT)) it happened snipped-for-privacy@gmail.com wrote in :

You can also put the 10 Hz on a speaker, and reflect it of a window, or some other vibrating object, use a microphone to detect the varying phase return signal. look up radar.

The reflecting object can be both on the left- and on the right side.

The MXR Phase 90 came out circa 1974:

Probably only need a single stage with associated JFET driven from filtered noise

Several people sell switch-based programmable resistors. That's fairly easy, except that they glitch when you change the value. That can cause problems simulating the inputs to some systems, liker when a simulated 150 degrees C passes through 1000 for a couple of milliseconds on its way to 150.2.

--

John Larkin   Highland Technology, Inc   trk 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

It's easy to do, and x could be curved too.

If x=0.5, you get 45 degrees with gain 0.707. At x=0.55, it's 50.7 degrees and 0.710. Probably good enough.

--

John Larkin   Highland Technology, Inc   trk 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

On a sunny day (Sat, 28 Oct 2017 09:28:56 -0700) it happened John Larkin wrote in :

Yes, Maxim makes ome interesting CMOS switches, also some with low Ron, but the charge injection gets bigger as the Ron gets lower:

I think it is not impossible to compensate the transients somehow, I think it maybe needs trimpots...

Just had a thought... what is your definition (system needs) for "phase shift"?

If all you care about is zero crossings, just add noise to the baseline. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
     It's what you learn, after you know it all, that counts.

I've seen that same circuit implemented with MOSFETs (rather than JFETs) as control elements. The FETs were the N-ch half of the output of a 4069 hex inverter, and the control voltage was the supply voltage of the 4069.

There's a crude ASCII-art schematic at the end of this thread from 2006:

Allan

There are linearization techniques for both JFET and MOSFETs, for such applications, that work quite well. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
     It's what you learn, after you know it all, that counts.

Here's a PWM-based phase shifter.

The lead and lag phase angles could be whatever you need, not necessarily 45 degrees or anything obvious like that. The mux is a cheap CMOS thing, an HC4051 type maybe.

The buffer opamps aren't mandatory, but allow reasonable RC values to make phase shifts at 10 Hz.

PWM multipliers were used for precision processing in the days before uPs. A classic application was to make a precision (< 0.1% accuracy) square root to process the analog signal from a flowmeter, which used an orifice plate and a differential pressure sensor in a pipeline. The dp went as the square of flow rate. Megabucks changed hands every day based on the measurement.

--

John Larkin   Highland Technology, Inc   trk 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com