Voodoo Main Discussion

[surfdetector]

I got my 3R3 2w resistor and installed it and the wave looked more similar to the book but not the same yet on TP5 and TP2 i was reading that the clip is the ground for the probs on my oscilloscope and connected it to TP14 thinking that it might have to be grounded the screen went white boxes with just a back ground shut it off and now nothing on anything and 10 volts all over the board so i guess i get to learn how to check parts and repair it now starting with the 78L05 and the 79L05 and anything else i find i destroyed where is the clip suppose to be grounded to ?

TP1 (+12V battery) is the ground reference for the project. This is what your oscilloscope ground clip should be clipped to not TP14 which is (-5V ) supply
Have you read a copy of the book? It explains most everything in detail.

[Qiaozhi]

I got my 3R3 2w resistor and installed it and the wave looked more similar to the book but not the same yet on TP5 and TP2 i was reading that the clip is the ground for the probs on my oscilloscope and connected it to TP14 thinking that it might have to be grounded the screen went white boxes with just a back ground shut it off and now nothing on anything and 10 volts all over the board so i guess i get to learn how to check parts and repair it now starting with the 78L05 and the 79L05 and anything else i find i destroyed where is the clip suppose to be grounded to ?

As surfdetector said: TP1 is the reference point. See page 28 of the book.

Are you using a bench power supply or a battery pack? If it's a bench power supply you may find that the 0V line is connected to earth. If your scope's 0V line is also connected to earth then you could create a short-circuit.

I would suggest reading the book very carefully to gain an understanding of how the design works, otherwise you're going to encounter a whole host of other problems. Personally I would advise putting the Voodoo Project on one side and building a much simpler design first so that you actually know what you're doing.

As it says in the Introduction:
"Please do not even attempt this project without having built a standard (PI and/or VLF) metal detector before."

[waltr]

Got my VooDoo board stuffed, last parts came yesterday.
So far only have the LT1054 and the PIC chips installed plus the LCD.
These power up and the LCD display is working.
Next is to connect a coil and start inserting the remaining ICs checking with a scope as I go.

[SilverSurfer17]

Yes im using a computer for the 12 volts and i don't want to build another detector why not call a ground a ground -5 -12 and +5 or +12 positive and yes i skimmed through it and im not the only in here who has had problems with this project and im sure they have built other detectors and i would make the same mistakes voodoo or pi surf and besides ordering 3.3 ohms and ordering 33 ohms its the first problem ive had and like i said before ill blow it up 100 times until i learn everything there is about voodoo so im not going anywhere

[SilverSurfer17]

But you both are also correct i shouldn't of skipped over parts of the book to learn a ground isnt ground if its plugged into a wall coming out of a power supply or out of a battery

[SilverSurfer17]

So then when it says tp5 channel 1 the hook goes on tp5 tp2 channel 2 tp2 is the hook and the both ground alligator clips go tp1 which is actually a positive ?

[SilverSurfer17]

Bizzaro world where the positive of a battery is the ground

[SilverSurfer17]

And im not mad George like i said from the get go if i blow it up its not the end of the world i know i can always replace the parts and that $10 for the parts and shipping was worth it to learn that ground isn't ground lol

[Qiaozhi]

Yes im using a computer for the 12 volts and i don't want to build another detector why not call a ground a ground -5 -12 and +5 or +12 positive and yes i skimmed through it and im not the only in here who has had problems with this project and im sure they have built other detectors and i would make the same mistakes voodoo or pi surf and besides ordering 3.3 ohms and ordering 33 ohms its the first problem ive had and like i said before ill blow it up 100 times until i learn everything there is about voodoo so im not going anywhere

That's your problem then, as the computer's power supply will have one side connected to earth.

[Qiaozhi]

So then when it says tp5 channel 1 the hook goes on tp5 tp2 channel 2 tp2 is the hook and the both ground alligator clips go tp1 which is actually a positive ?

When it says channel 1 is connected to TP5, and channel 2 to TP2, this means that the earth clip is connected to TP1 (GND).
Some circuits (but not Voodoo) have more than one "ground", depending on which signal you're measuring. There is even such a thing as a virtual ground.

[billr]

http://www.lowgif.com/view.html

[SilverSurfer17]

Ok George those clips go to TP1 and the test points are the hooks got it and yes I've never heard of virtual ground my brain is stuck in automotive 12 volt and the only thing I've ever used a oscilloscope for was fuel injectors in school 3 decades ago because i learned how to just use a noid light and never needed a scope after that so when i saw those clips where ground and it was using 5 volts i went right for the 5 volt ground

[waltr]

"Ground" should really be called "Reference" since this is the node that all measurements are referenced to.
If you think of it this way then all makes better sense.

Many have had issues using bench power suppllies for detector circuits.
First issue is 'earth grounding' and shorts when using the scope.
Second is noise coming from or through the bench PS.
Third is current surge and flyback issues.

I and many others use a batter to power the detector circuit. This way the power is isolated.
I use a 3 cell LiPo battery with a 40W automotive tail light bulb in series as a current limiter.
Then when (not if) you mess up and short the power, the bulb lights and limits current to about 3-4Amps and nothing blows up.
This has saved me more than a few times.

[Carl-NC]

Bizzaro world where the positive of a battery is the ground

This is common in the world of PIs that use low-side (NMOS/NPN) switches on the coil. It simplifies domain voltages but you gotta be careful when using a bench power supply combined with an oscope or a programmer.

[SilverSurfer17]

Yeah i see that now but thats also why I'm here to learn something new besides the little i do know i knew i could get a board to kinda work but tuning it and making the best coils for that detector and learning their relationship i would have to learn also the programming part i always cringed at because of the dos base typing part of it thats why i do like this Mikro P its copy paste and GUI based and has a nice help and search feature so i wont lose interest in trying to figure it out or watching the 25 videos each over 1 hour and 35 minutes long lol