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Specification


Andres Ramos

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OK, as a follow up to my discussions with Jeff we can propose the following design specification of the Light Bridge.

 

Design specification

  • Built in microphone and an additional 3,5mm stereo line input (mono internal) for modulating the light bridge. Two potentiometers for leveling microphone and external signal. Both signals are mixed and can be used simultaneously.
  • Current driver for modulating one white LED inside the closed unit.
  • Solar cell receiver with preamplifier working as a trans-impedance amplifier. LED will be operated linearly and symmetrically.
  • Received signal from solar cell will be band pass filtered (300Hz .. 5KHz)
  • LED clipping indicator to detect over-modulation
  • 0 dBm audio jack output (stereo with mono signal) for recording.
  • Adjustable headphone output (optional)
  • External 12VDC power supply applied via standard DC power socket (Reverse polarity protected). Thus every standard 12VDC wall adapter should be suitable.
  • Hum and EMI filter in DC power supply path
  • Plastic Housing

 

User control elements and indicators

  • Switch: Power ON/OFF
  • Potentiometer: Mic Level
  • Potentiometer: External audio input
  • socket: 3,5mm line audio jack on front panel for headphones (optional)
  • Potentiometer: headphone volume (optional)
  • socket: 3,5mm line audio jack on backside for recording
  • LED: ON/OFF
  • LED: Signal clipping

@Lance/Jeff please confirm specification or require changes.

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1 hour ago, Lance Reed said:

Hi All, 
Yes, I am really excited to start using the Light bridge, I record mostly everyday early in the morning,  to get ongoing advice from my spirit team and also record for people around the world that are in Grief.  
I am currently working with the Argotlunar software (Granular synthesis)  that Jeff introduce me to, I also have been talking with Sonia and she is going to try using the Argotlunar software for her to break up the voices. 
When using the Light bridge device, I will report back to you guys frequently on the progress and clarity of voice contacts that come through.

Let the force be with us 🙂

Take care, Lance.



 

That'll be great Lance. If you will be successful with the Light Bridge we could replicate it for other Varanormal members.

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17 hours ago, Dr Jeffers said:

To help explain the Light Bridge a bit more clearly, here are some captures from a video Sonia did containing an overview of the V1 Light Bridge. This first version was a simple device that translated audio into a modulated light beam, that was received by a phototransistor in the receiver and converted back to audio again. The later versions of the bridge had LEDs of varying wavelengths, more input and output facilities, etc, but the basic principle remains the same.

The idea of using light came into being through various ways, but it was a response she received from Raudive that initially set the path towards light being used.

Sonia's preference is working with trans-image reception, so it is unlikely we will see much more done on this audio based concept.

 

 

 

Thanks for sharing Jeff!   

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I was mentally prompted that I need to add some important comments here regarding the other crucial element in the Light Bridge system, and that is the Operator.

The device by itself in isolation has no special magic, and as such is just a collection of parts that perform a function - that is to convert audio into a modulated light beam, and then back into audio again. Where the magic enters is when the operator becomes sufficiently entangled with the device, and this entanglement brings into being the psychokinetic functionality that transforms the incident audio into an ITC message for the operator to discern.

In the device we have at least 2 psychokinetic modulators (a term first coined by Bill Weisensale), and these are the electret mic and the solar cell. Both are transducers, which means they convert energy or force into an electrical charge. The action of entanglement by the operator modifies the energy conversion process inside these transducers - effectively modulating it, and hence the audio based variations (in force or energy they are being routinely converted) are hence modified into a voice. There are other types of pk modulators, but this device has 2, and as such it means that the audio has 2 chances of being pk modulated in a seriesed fashion, in effect meaning the modulation effect (%) is multiplied in value, and hence the clarity of the message is improved, compared to having only on pk modulator.

There is more to say about how spirit intent enters the equation - in relation to the Operator, but I will do this later.

 

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8 hours ago, Dr Jeffers said:

I was mentally prompted that I need to add some important comments here regarding the other crucial element in the Light Bridge system, and that is the Operator.

The device by itself in isolation has no special magic, and as such is just a collection of parts that perform a function - that is to convert audio into a modulated light beam, and then back into audio again. Where the magic enters is when the operator becomes sufficiently entangled with the device, and this entanglement brings into being the psychokinetic functionality that transforms the incident audio into an ITC message for the operator to discern.

In the device we have at least 2 psychokinetic modulators (a term first coined by Bill Weisensale), and these are the electret mic and the solar cell. Both are transducers, which means they convert energy or force into an electrical charge. The action of entanglement by the operator modifies the energy conversion process inside these transducers - effectively modulating it, and hence the audio based variations (in force or energy they are being routinely converted) are hence modified into a voice. There are other types of pk modulators, but this device has 2, and as such it means that the audio has 2 chances of being pk modulated in a seriesed fashion, in effect meaning the modulation effect (%) is multiplied in value, and hence the clarity of the message is improved, compared to having only on pk modulator.

There is more to say about how spirit intent enters the equation - in relation to the Operator, but I will do this later.

 

Hi Jeff. This is an important information and it matches very well our previous results in other experiments. For me now the question is if we should discard the line input and only make use of the microphone? However the setup then would seriously deviate from what Sonia did. I would keep in the line input as it consumes not much components.

 

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Hi Andres, I think it would we wise to keep the line input, as it might be used for introducing an additional source of sound at a later point, and as you say, it doesnt use a lot of components.

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HI Andres, good design.

A couple of things: were you going to add an LM386 headphone amp, and I have a little concern the mixer opamp output may not be able to swing down to 1V due to saturation limitation, and hence not reach the clipper threshold. The datasheet I looked at was vague about this.

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6 hours ago, Dr Jeffers said:

HI Andres, good design.

A couple of things: were you going to add an LM386 headphone amp, and I have a little concern the mixer opamp output may not be able to swing down to 1V due to saturation limitation, and hence not reach the clipper threshold. The datasheet I looked at was vague about this.

A good point Jeff. I'd need to use a rail to rail OpAmp or to narrow down the clipping area. I will look into the data sheet of the OpAmp. Basically the output swing should be specified. If not I would presume a maximum lower limit of 2V.

Yes, I forgot the LM386 in the schematic. Even it's just a module but I should place it into the schematic too of course.

Will revise the schematic again.

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HJi Jeff,

I updated the schematic. From what I found about data for the TL071 it is regarded as a rail-to rail OpAmp. The datasheet is a little more specific and states a negative rail headroom of max 1030mV at Vsup=40V and 2k load. I think 1V headrrom, like it is already considered in the design, should suite very well. The positive headroom is 935mV but this area is already limited by the forward voltage of the LED which I assumed to be 2,7V due to the LED's I worked with. However this value can go up to 5V depending on the used technology. I will keep it like this for now and will adjust the upper headroom for the clipper if necessary.

Light-Bridge Schematic - Sheet 1.JPG

Light-Bridge Schematic Sheet 2.JPG

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Yes, its good you can confirm this Andres, as the datasheets I read were vague about operating at 9v single ended. As you say, it will probably be close as to whether 1v is achievable or not, but can be mitigated.

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I did a test on a couple of TLO71's here using 9V supply, and the output definitely wont swing down to 1v with a light load. About 1.7V is about it for low limit, using 33k for load. I got it down to 1.1V by using a 10k load instead - but shouldnt have to bully it like this.

Edited by Dr Jeffers
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2 hours ago, Dr Jeffers said:

I did a test on a couple of TLO71's here using 9V supply, and the output definitely wont swing down to 1v with a light load. About 1.7V is about it for low limit, using 33k for load. I got it down to 1.1V by using a 10k load instead - but shouldnt have to bully it like this.

Oh, ok. So the lower limit needs to be revised or a true R2R OpAmp should be used. I remember faintly I have some in my box that are true R2R and designed for single voltage supply use.

I won't change the schematics again for now because I expect more correction to be done after making and testing the breadboard layout. Maybe it's a good idea to write a report about the completed device with test results in the experiments section including the latest revision of the schematic.

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OK, I just couldn't keep my fingers from it. By checking my component stock I found some TS912, a Rail-To-Rail OpAmp very similar to the TL072 or LM358 with standard case and pinout. The output goes as near as 40mV to the respective rail. I kept the component values for the clipper because now the lowest clipping border is 1V and that means roughly 0.3V on  R10 and I don't want the voltage to fall below that value. I worked it into the schematics and while I was doing this I also corrected a lot of false component annotations. So again see here tha latest revision of the schematics.

Transmitter section

Light-Bridge Schematic - Sheet 1.JPG

Receiver section

Light-Bridge Schematic Sheet 2.JPG

 

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On 8/15/2021 at 8:22 PM, Andres Ramos said:

I found some TS912, a Rail-To-Rail OpAmp very similar to the TL072

Yes, that IC is a good substitution Andres, and eliminates the swing limitation. I had some comments on the design that Id like to share, and they relate to the comparison to Sonia's Light Bridge unit.

Firstly, her unit uses LEDs and photodiodes (it looks like) as well as an electret mic. In use, the mic in her unit is only used for voice announcements, so is not passing the carrier chunked speech. So as far as pk modulators are concerned, the mic is not involved in the process, and I would consider the photodiode as not being an effective modulator, so overall, would not rate her device very highly from a strict ITC hardware perspective. Our unit on the other hand has the electret mic as the main acoustic pickup for carrier sound, and it has a solar cell as the receptor, and I rate both elements as being active pk modulators. So, I think we have therefore effectively improved the design, if our assessment of Sonia's unit and its componentry is correct.

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I need some advice on a mechanical question, Jeff. Is there a rule to follow how big the gap between the solar cell and the LED should be? If not I would just align the gap size with the mechanical constraints of the housing somehow?

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I dont think this is critical Andres. In Sonia's unit, it looked like 5cm. What I think is quite critical is the amount of light falling on the cell. Assuming the LED is biased at a suitable q point, where maximum linearity occurs at near to max modulation limits (this current q point will need to be determined), then whatever that amount of light being emitted will need to be attenuated by some sort of optical screen, so the incident light level on the solar cell is much less, and as such, generates emf in the cell, but also a degree of noise. I feel the cell is most likely to be pk active if the incident light is barely creating a low distortion emf. I hope this makes sense. In final test, the optical screen can be adjusted to get the best pk modulation.

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1 hour ago, Dr Jeffers said:

I dont think this is critical Andres. In Sonia's unit, it looked like 5cm. What I think is quite critical is the amount of light falling on the cell. Assuming the LED is biased at a suitable q point, where maximum linearity occurs at near to max modulation limits (this current q point will need to be determined), then whatever that amount of light being emitted will need to be attenuated by some sort of optical screen, so the incident light level on the solar cell is much less, and as such, generates emf in the cell, but also a degree of noise. I feel the cell is most likely to be pk active if the incident light is barely creating a low distortion emf. I hope this makes sense. In final test, the optical screen can be adjusted to get the best pk modulation.

I completely understand. In my experiments with an LDR as a receiver for modulated light, I used it in low light mode. In this setup I used raw rock crystal as a diffuser.

Anyway we will need to put something in between the cell and the LED that lowers the light.

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I am grateful we have a space to care and share losses and wins.  Thank you to you all for explaining what you are doing.  For the untechnical brain I am grateful to have the smallest of things explained.  Sending you all a pat on the back for a working job done.  I love how you are all so open to working with each other and publically.  Thank you,

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5 hours ago, Karyn said:

I am grateful to have the smallest of things explained.

Thank you Karyn. If you or anyone else needs more explanation, or has questions, please let us know. Its important that everyone benefits from the work we as individuals and teams collectively do.

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10 hours ago, Andres Ramos said:

Anyway we will need to put something in between the cell and the LED that lowers the light.

Yes indeed. One other thing of importance that I forgot to add to my last post is the illumination area of the cell. From my experiments, it seems that the area illumination needs to be as full as possible, so it covers most or all of the cell. With an LED of narrow beamwidth, it would require some sort of divergent lens or diffuser in order to provide this wide spread. Perhaps your rock crystal could do this, as well as act as an attenuator, Andres?

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