Voodoo Main Discussion

[Qiaozhi]

Yeah I saw that too and that's exactly what you did right!
There are two things to consider:
1) surely someone built the metaldetector without any problems, which proves the schematic is correct.
2) for some others, me included, it doesn't work: in my case how can you explain the perfect wave on pin Osc without the need of an external pull-up resistor? The only explanation is that a pull-up is already present!
Moreover the output and the pin Osc initially have a 10khz wave 50% then when the micro activates they syncronize and produce a wave form exactly like TP9 but at 12V, this proves the correct operation took place.
With the external resistance the wave on pin Osc is extremely tilted on the ascent and the width is around 9V, without touching neither 0V nor -12V and the output doesn't oscillate.

There may be a need to find an errata corrige of the datasheet or wait for someone whose metaldetector doesn't work and have them take out R48 and then see what happens.

As far as I'm aware, no-one else has encountered this problem. Also, I've used this configuration in several designs without any issues.

The 7660 does not require a pull-up resistor when driven by an external clock, which makes me a little suspicious of your LT1054's authenticity. Maybe it's a 7660 disguised as an LT1054.
I'm going to set up a test rig in a prototyping board, and test both an LT1054 and a 7660 to confirm that the former does not have an internal pull-up resistor.

[nixie]

Look at Fig.12 in the LT1054 datasheet. It shows an external resistor between pins 7 and 6. Also, it states in the text:
"Synchronization can be accomplished by adding an external resistive pull-up from Pin 7 to the reference pin (Pin 6). A 20k pull-up is recommended. An open collector gate or an NPN transistor can then be used to drive the oscillator pin at the external clock frequency as shown in Figure 12. Pulling up Pin 7 to an external voltage is not recommended."

Yeah I saw that too and that's exactly what you did right!
There are two things to consider:
1) surely someone built the metaldetector without any problems, which proves the schematic is correct.
2) for some others, me included, it doesn't work: in my case how can you explain the perfect wave on pin Osc without the need of an external pull-up resistor? The only explanation is that a pull-up is already present!
Moreover the output and the pin Osc initially have a 10khz wave 50% then when the micro activates they syncronize and produce a wave form exactly like TP9 but at 12V, this proves the correct operation took place.
With the external resistance the wave on pin Osc is extremely tilted on the ascent and the width is around 9V, without touching neither 0V nor -12V and the output doesn't oscillate.

There may be a need to find an errata corrige of the datasheet or wait for someone whose metaldetector doesn't work and have them take out R48 and then see what happens.

[Qiaozhi]

Finally! I have the solution!
Obviously the circuit was correctly assembled!
I noticed that the signal on pin OSC wasn't right and not wide enough (hence why I asked you to post the images) then when I looked over the lt1054 datasheet. I though about taking off transistor Q6 and resistance R48 (pull-up 20k between Vref and Osc) in order to make the circuit independent as Positive-VoltageDoubler and, magically, I got on pin 2 a perfect 10khz wave and my +5V!!!
I reconnect transistor Q6 and my +5V are still present and on pin Osc there is the wave present on TP9 with an amplitude of 12V and perfectly squared!!! OK! Maybe I had connected something the wrong way...
But then I reconnect Resistance R48 (pull-up) and the circuit stops working!
This makes me think that on pin Osc there already is an internal pull-up resistance not mentioned in the datasheet (in my opinion this is proved by the fact I got the correct square wave without external pull-up) and when we connect the external pull-up this makes the functions of pin Ref go haywire.
Solution:
in my case you just need to disconnect the 20k R48 resistance and the +5V will magically appear.
My LT1054 from Linear Technology have been built the third week of 2019.
I hope this can be useful to you.

Look at Fig.12 in the LT1054 datasheet. It shows an external resistor between pins 7 and 6. Also, it states in the text:
"Synchronization can be accomplished by adding an external resistive pull-up from Pin 7 to the reference pin (Pin 6). A 20k pull-up is recommended. An open collector gate or an NPN transistor can then be used to drive the oscillator pin at the external clock frequency as shown in Figure 12. Pulling up Pin 7 to an external voltage is not recommended."

[nixie]

U8 pin6 provides a reference voltage of +1.8V relative to -VB.
Therefore there should be a pulsed waveform (SYNC) at U8 pin7 with an amplitude of 1.8V relative to -VB.
At U8 pin2 there should be a pulsed waveform that swings between 0V and -12V (measure relative to 0V).
At cathode of D6 there should be around +8V DC relative to 0V.

Now ... this may be a stupid question, but you do have U8 inserted the correct way round? This IC faces downwards on the PCB, whereas all the other 8-pin devices face upwards.

Finally! I have the solution!
Obviously the circuit was correctly assembled!
I noticed that the signal on pin OSC wasn't right and not wide enough (hence why I asked you to post the images) then when I looked over the lt1054 datasheet. I though about taking off transistor Q6 and resistance R48 (pull-up 20k between Vref and Osc) in order to make the circuit independent as Positive-VoltageDoubler and, magically, I got on pin 2 a perfect 10khz wave and my +5V!!!
I reconnect transistor Q6 and my +5V are still present and on pin Osc there is the wave present on TP9 with an amplitude of 12V and perfectly squared!!! OK! Maybe I had connected something the wrong way...
But then I reconnect Resistance R48 (pull-up) and the circuit stops working!
This makes me think that on pin Osc there already is an internal pull-up resistance not mentioned in the datasheet (in my opinion this is proved by the fact I got the correct square wave without external pull-up) and when we connect the external pull-up this makes the functions of pin Ref go haywire.
Solution:
in my case you just need to disconnect the 20k R48 resistance and the +5V will magically appear.
My LT1054 from Linear Technology have been built the third week of 2019.
I hope this can be useful to you.

[Qiaozhi]

The hex code contains the fuse settings, and a PICkit uses those when programming the PIC.
I've never used a TL866A minipro programmer. What does it require for fuse settings? Is it a file, or do you simply type in some numbers?

[surfdetector]

How is the correct fuse settings for the PIC18F4520?
I am getting an error with TL866A minipro programmer[ATTACH]55139[/ATTACH]

I think most of us used a PICkit to load the hex file

[andon80]

How is the correct fuse settings for the PIC18F4520?
I am getting an error with TL866A minipro programmer

[Qiaozhi]

I finally got almost all the components and I built the circuit (lacks mosfet tx and ic for filters),
first of all I wanted to test the voltages and the signals generated by the CPU:
these signals are the exact same as those described in the manual, voltage -5V ok but +5V is not present!!!
On tp9 the signal is perfect, on U8 the tensions on pin 8 = 0V (+VB), on pins 3 and 5 = -12V (-VB)
on pin 6 and 7 there is a signal very similar to SYNC but not perfectly square and amplitude around 8-9V starting from -12V
on pin 2 there is no oscillation.
I changed the 78l05 and 4 pieces of Lt1054 it does not change anything.
If I disconnect D6 and/or take off U7 nothing changes (no oscillation on pin2), same thing with a icl7660s.
Anybody can give me some advice?
George, can you post the image that's on pin 6 and 7 of U8?
thanks in advance

P.S.: powered by a 3-30V 10A desk power unit.

U8 pin6 provides a reference voltage of +1.8V relative to -VB.
Therefore there should be a pulsed waveform (SYNC) at U8 pin7 with an amplitude of 1.8V relative to -VB.
At U8 pin2 there should be a pulsed waveform that swings between 0V and -12V (measure relative to 0V).
At cathode of D6 there should be around +8V DC relative to 0V.

Now ... this may be a stupid question, but you do have U8 inserted the correct way round? This IC faces downwards on the PCB, whereas all the other 8-pin devices face upwards.

[surfdetector]

Anybody can give me some advice?
George, can you post the image that's on pin 6 and 7 of U8?
thanks in advance

P.S.: powered by a 3-30V 10A desk power unit.

I did a series of build videos for the Voodoo detector. You might find them helpful

https://youtube.com/playlist?list=PLgBlcFVgN7pTgYK7McUNy2u3m-SRFjPFy

[nixie]

I finally got almost all the components and I built the circuit (lacks mosfet tx and ic for filters),
first of all I wanted to test the voltages and the signals generated by the CPU:
these signals are the exact same as those described in the manual, voltage -5V ok but +5V is not present!!!
On tp9 the signal is perfect, on U8 the tensions on pin 8 = 0V (+VB), on pins 3 and 5 = -12V (-VB)
on pin 6 and 7 there is a signal very similar to SYNC but not perfectly square and amplitude around 8-9V starting from -12V
on pin 2 there is no oscillation.
I changed the 78l05 and 4 pieces of Lt1054 it does not change anything.
If I disconnect D6 and/or take off U7 nothing changes (no oscillation on pin2), same thing with a icl7660s.
Anybody can give me some advice?
George, can you post the image that's on pin 6 and 7 of U8?
thanks in advance

P.S.: powered by a 3-30V 10A desk power unit.

[MartinB]

As promised ...

An adapter board that allows an Arduino Nano to be fitted in place of the original PIC18F4520 has been created.
There is a short description in PDF format attached below, along with the DipTrace files, Gerber and NC/Drill, and the Arduino sketch.

Enjoy!

Errata:
1. There is a typo in the PDF document on page 4. It should say "A jumper wire needs to be soldered between TP2 and TP18" ... not TP21.
2. It's C8 that needs to be moved to the underside of the PCB, not C22.

Thanks George.
Nice code.

[Qiaozhi]

I believe there is a small typo within the pdf document where it states "Since C22 (22uF) causes a clash with the underside of the adapter board, it needs to be soldered on the bottom of theVoodoo PCB. R23 and R24 should also be installed before the adapter board is soldered in place."

That should be C8 which needs to be moved to the underside of the PCB

Damn ... you're correct.
That's what happens you write these things up late at night.
At least someone is paying attention.

[6666]

You can see on the adapter board that there are two footprints that overlap each other. CONN1 is the connector for the PIC, and U1 is the Arduino Nano. You need to solder two 20-pin male headers to the bottom of the adapter to allow it plug in where the PIC usually goes, and two 15-pin female headers on the top of the adapter so that you can plug in the Nano. The 3D images below should show this more clearly.

Thanks the 3d pictures explains it ,

[surfdetector]

As promised ...

An adapter board that allows an Arduino Nano to be fitted in place of the original PIC18F4520 has been created.
There is a short description in PDF format attached below, along with the DipTrace files, Gerber and NC/Drill, and the Arduino sketch.

Enjoy!

Errata:
1. There is a typo in the PDF document on page 4. It should say "A jumper wire needs to be soldered between TP2 and TP18" ... not TP21.

I believe there is a small typo within the pdf document where it states "Since C22 (22uF) causes a clash with the underside of the adapter board, it needs to be soldered on the bottom of theVoodoo PCB. R23 and R24 should also be installed before the adapter board is soldered in place."

That should be C8 which needs to be moved to the underside of the PCB

[nixie]

Personally I would like to move on to exploring something completely different. More later...

Yes! it's right!