Voodoo Main Discussion

[Matt_Rowe]

I don't want to have to buy 15 different ohm values for it if there is a way with the jig to know the exact ohm value of what it needs from what ive seen those type resistors aren't cheap i knew i would have problems with the tuning part i didn't think as much building the board ill check all the values later on the resistors to make sure they are what they are suppose to be

Look at surfdetectors video on how to use the jig

[Qiaozhi]

OK I've misunderstood the goals here. I thought we are talking more about proof of concept design.
You guys shoot for high performance top of range etc.
Yes a 50$ ADC is a sweet thing to have, if you have already covered the basic goals of your design and you're limited by MCU performance.
I'm doing a ADC/PWM with the PIC32MZ (which uses a 12Bit ADC) and it's not all that great but I can live with it for now, and I can focus on the rest of the design.

BTW I don't digitize the analog signal so ADC accuracy shouldn't alter the performance /like on the voodoo there/. I simply use it to vary the tone of the PWM so ADC accuracy is no big deal.

Why all this? Simply I've read the book and got inspired to pursue similar goals like the voodoo project /it's just proof of concept design/

At least someone gets it.

[eclipse]

OK I've misunderstood the goals here. I thought we are talking more about proof of concept design.
You guys shoot for high performance top of range etc.
Yes a 50$ ADC is a sweet thing to have, if you have already covered the basic goals of your design and you're limited by MCU performance.
I'm doing a ADC/PWM with the PIC32MZ (which uses a 12Bit ADC) and it's not all that great but I can live with it for now, and I can focus on the rest of the design.

BTW I don't digitize the analog signal so ADC accuracy shouldn't alter the performance /like on the voodoo there/. I simply use it to vary the tone of the PWM so ADC accuracy is no big deal.

Why all this? Simply I've read the book and got inspired to pursue similar goals like the voodoo project /it's just proof of concept design/

[Qiaozhi]

Or can i remove the coil and just use the jig ... ?

[KingJL]

Is 22 bit A-D, no amplifier better than 12 bit AD with a fast low noise amplifier gain=1000? If yes, why?

Quite simply "dynamic range". The "gain = 1000" should say it all! But you can't have a 22 bit ADC and no amplifier either... But you can have a 22 bit ADC and a amp with a gain < 10 with a nyquist filter.

[surfdetector]

Here is what the output of tx is with jig installed and the prob on pos and negative on neg and channel 2 on tp2

I recommend that you perform some oscilloscope probe compensation.

https://youtu.be/CzFzqGawmvU

[SilverSurfer17]

All the wave form diagrams is that with a damping resistor and coil attached ? Or can i remove the coil and just use the jig and concentrate just on the board until my waves forms match the book ?

[green]

Totally agree... I have been preaching that for 3+ years. Twelve bits simply just do not cut it!

Is 22 bit A-D, no amplifier better than 12 bit AD with a fast low noise amplifier gain=1000? If yes, why?

[SilverSurfer17]

No i never checked each part individually ive never had to in the past but then again i assembled and tested not had to fix boards so i can figure some things out i barely even know how to use this oscilloscope lol

[SilverSurfer17]

I don't want to have to buy 15 different ohm values for it if there is a way with the jig to know the exact ohm value of what it needs from what ive seen those type resistors aren't cheap i knew i would have problems with the tuning part i didn't think as much building the board ill check all the values later on the resistors to make sure they are what they are suppose to be

[KingJL]

Two words; Dynamic range!... 18bit ADC minimum for a detector, anything less is false economy.

Totally agree... I have been preaching that for 3+ years. Twelve bits simply just do not cut it!

[Sean_Goddard]

Two words; Dynamic range!

ADC's give a theoretical 6dB per bit. Amplification has nothing to do with this issue.

To make a rally SENSITIVE, and deep machine, you would require some 124dB of dynamic range. You can do this 2 ways, switched gain or more bits.

Robert Hoolko proposed switched gains (3dB = gain of 2X ) so 60dB is gain of 1x10^6 or 1 million. In emails to him, I proposed more bits specifically 24 with a 192khz sample rate. After we analysed the merits of both methods, more bits won because switched gain introduces response lag (like an auto ranging DMM). I would use an I2C 18bit ADC minimum for a detector, anything less is false economy.

[SilverSurfer17]

Here is what the output of tx is with jig installed and the prob on pos and negative on neg and channel 2 on tp2

[SilverSurfer17]

Can i use the jig to check that for the damping resistor or does the tx use 10.5 and the jig is for rx i dont understand the purpose of the jig if there is a calculation to figure out the damping resistor and the book says trial and error is best

[Matt_Rowe]

Im going to just order 1/4 watt resistors and replace those monsters i put in can i use just the jig or do i need to order a certain size like 10.5 or some starting point resistor ?

did you check every part manually before you installed it, very good point the surfdetector made a video on, and in making the video proved a resister, or a part was bad right out of the package.
its a little chore, but he proved well worth the effort. all new parts are not good from the manufacturere in electrical parts, same with autos and our electrical parts for us electricians

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