Voodoo Main Discussion

[6666]

Bad luck!
Just as i finished all on boards.
I learned now that i can not use damn (now useless to me) "Ready for Pic" dev board to program 18F4520 chips.
18F45K22 which is on the board originally; is having bootloader, that's why it is accepting flashing.
OK, so i tried last option; i put 18F45K22 flashed with Voodoo hex on the pcb.
Not working. Seems some functions are working, like sync signal, since LT1054 (had one!) is working alright, providing voltages.
But nothing on LCD and when both TL072 are in sockets; 5v from 78L05 drops to 0.3v!!??
When i pull out both TL072 and all other chips are on sockets; i get +5.05v alright.
When i put back only one TL072; voltage drops to +4.6v. When put back second TL072; drops to 0.3v!
Same on both pcbs.
When both TL072 pulled out; all the voltages are there. Nothing on LCD.
Although all 4 TL072 (2 pcbs) are brand new, yet i tried several other dual opamps there, just to be sure... same behavior.
So... my conclusion; since both TL072 are directly tied to mcu, and mcu is not 18F4520 but 18F45K22; some conflict happens and voltage drops.
Fortunate situation is that i made 2 pcbs, totally the same. So i can simply rule out any eventual mistake that i made during the soldering process.
Since both pcbs behaving the same.
Bad luck is that right now i don't have tools to program those two empty 18F4520's.
So i'll have to order now PICKIT and wait several days to arrive.
Sheeeeesshhhh!
I have horrible urge to swear now very ugly!

I hope you get your voodoo working
re programming the 4520, I found something that may help, the 4520 is listed, with you being a arduino wizard it may work for you

https://sites.google.com/site/thehighspark/arduino-pic18f

a bit more info here

http://pleasantlyclueless.blogspot.com/2013/11/using-arduino-as-pic-programmer.html

[ivconic]

Bad luck!
Just as i finished all on boards.
I learned now that i can not use damn (now useless to me) "Ready for Pic" dev board to program 18F4520 chips.
18F45K22 which is on the board originally; is having bootloader, that's why it is accepting flashing.
OK, so i tried last option; i put 18F45K22 flashed with Voodoo hex on the pcb.
Not working. Seems some functions are working, like sync signal, since LT1054 (had one!) is working alright, providing voltages.
But nothing on LCD and when both TL072 are in sockets; 5v from 78L05 drops to 0.3v!!??
When i pull out both TL072 and all other chips are on sockets; i get +5.05v alright.
When i put back only one TL072; voltage drops to +4.6v. When put back second TL072; drops to 0.3v!
Same on both pcbs.
When both TL072 pulled out; all the voltages are there. Nothing on LCD.
Although all 4 TL072 (2 pcbs) are brand new, yet i tried several other dual opamps there, just to be sure... same behavior.
So... my conclusion; since both TL072 are directly tied to mcu, and mcu is not 18F4520 but 18F45K22; some conflict happens and voltage drops.
Fortunate situation is that i made 2 pcbs, totally the same. So i can simply rule out any eventual mistake that i made during the soldering process.
Since both pcbs behaving the same.
Bad luck is that right now i don't have tools to program those two empty 18F4520's.
So i'll have to order now PICKIT and wait several days to arrive.
Sheeeeesshhhh!
I have horrible urge to swear now very ugly!

[ivconic]

Moving forward... slowly...

[lamoiz]

Hi lamoiz
Thanks that looks like a good coil the pre amp looked like a 412 the way the turn off is but A 5532.
Last I tested I had slower coils I may revisit the 5532 I had given up on it finding the 4562 2 us faster out the door. at the time the 5532 wouldnt go below 8 us for me with the coil tested.
Out of curiosity what is your damping value?
Thanks

hi godigit, I did not have overheating of R2 when I connected my mono, this one has a damping resistance of 401ohm, (390 high tolerance ..) when I had done the test with the potentiometer, the value of 410 ohm would have been the best .. but I had that on hand ..

[godigit1]

Interesting your coil has low edge sensitivity. My figure8 coil detects almost the same edge distance as centered over one of the Rx coils. Coke can, Rx_(2)133mmID fig8. 24inches centered over one coil, 22inches from the side(same plane). Probably not good.

Hi Green,
I was rereading the thread and missed this post.

I wasn't able to follow completely you new coil build.
Not sure of the size but familiar with your design.
My planar coils have had seems like full edge depth as well I've stopped sitting so close. He he
The coil I've been testing is a dual field with the inner coil shaped like a D and a D Rx coil.

I've been thinking a little more that the edged detection was reduced by the small size of the Rx D coil.
At first I was thinking maybe the Tx outer coil may be running blocker but not so sure.
I'm making two larger Rx d coils to try see what happens.

Be Well.

Oh yea glad you guys got some fishing in.

[godigit1]

hi godigit, yes it is a mono coil that made a few years ago, and that I usually use on the mpp. On the picture it is on the voodoo, behind the original pream, ..

Hi lamoiz
Thanks that looks like a good coil the pre amp looked like a 412 the way the turn off is but A 5532.
Last I tested I had slower coils I may revisit the 5532 I had given up on it finding the 4562 2 us faster out the door. at the time the 5532 wouldnt go below 8 us for me with the coil tested.
Out of curiosity what is your damping value?
Thanks

[godigit1]

So far, I have not had any excessive heat on my project. What wattage resistor are you using?

Hey surfdetector,

it was a two watt resistor, I think I figured out what happened at least I hope so.
Ill figure it out here pretty soon as Im going ahead with the disc portions of the build.

I had wired my coil like a Mono on the MPP and didn't have the disc portion built so I think somehow I was overloading The R2 resistor.
strange though I had detection and the coil was damping.

I like the sound of the Voodoo.

[6666]

Hey guys just watch out for the value of R6, it is one ohm
the schematic printing in the book looks like part of a 3 but its a 1


And the value of R2 is 3.3 ohms (3R3) two watts, I dont have any two watt resistors so made it from two resistors
a one watt 2.2 ohm and a one watt 1 ohm, easy peasy.

[lamoiz]

Hi Lamoiz,

what pre amp are you using?
That doesnt look like a 5532.
Testing on the voodoo with a fast coil
I've had to damp it back to sample properly since the voodoo only goes to 15 us.
did you try any mono coil tests before disc assembly.
My R2 3r3 is getting hot did you have this Issue?

Has anyone had this issue?

Thanks

hi godigit, yes it is a mono coil that made a few years ago, and that I usually use on the mpp. On the picture it is on the voodoo, behind the original pream, ..

[surfdetector]

My R2 3r3 is getting hot did you have this Issue?

Has anyone had this issue?

Thanks

So far, I have not had any excessive heat on my project. What wattage resistor are you using?

[godigit1]

350 uh well damper with litz threads .. it works hard.
[ATTACH]54003[/ATTACH]

Hi Lamoiz,

what pre amp are you using?
That doesnt look like a 5532.
Testing on the voodoo with a fast coil
I've had to damp it back to sample properly since the voodoo only goes to 15 us.
did you try any mono coil tests before disc assembly.
My R2 3r3 is getting hot did you have this Issue?

Has anyone had this issue?

Thanks

[ivconic]

"...This might work, but the audio tone will then be 1kHz instead of 430Hz...."

Check this out: https://szynalski.com/tone#1007,squ,v0.75
Not that bad at all!

[ivconic]

DFX coils do not have tuning caps.

That's even better, no need for opening it.
With inductance ~540uH makes it good choice for Voodoo.

[Carl-NC]

DFX coils do not have tuning caps.

[ivconic]

"...I thought the DFX was wideband..."
Sorry if i made confusion, i mostly had Eagle Spectrum coils on my mind, the "Blue Max" and the "Black Max" so called coils and especially those with the rainbow lookalike stickers.
Those certainly do have several TX tuning caps inside. TX inductance is just perfect for fast PI coil and other good things that comes along (earlier sampling etc).
Whats even better; those are frequent and affordable coils today... what's even better; we had chance to see them opened so far, many times, on forum.
So is easy doable; the stripping. When it comes to DFX coils; i must say i am not sure about those.
Are those having anything from the caps inside or not.
Sorry for confusion.

"...This might work, but the audio tone will then be 1kHz instead of 430Hz...."
Yes, that would be the "catch 22"... but who ever had and got used on Musketeers; will not mind higher pitch. In time it becomes even pleasant.
We only have to put pros and contras in equation and see what is the real benefit from NE555 absence.
Personally, i don't like to see them on the same power supply with more delicate stages in the detector.
So 7660A will be! Thanks for the tip!