Arduino Nano VLF Metal Detector Project - Main Discussion

[Qiaozhi]

I did have a problem with the footprint of c10 c30 c41 the last 2 are fine but I can't find caps to fit the footprint so they are sitting on top my question is there ones that fit that footprint?

These capacitors are fairly standard types with a 5mm pin spacing.
Here's an example from Farnell:

https://uk.farnell.com/kyocera-avx/sr301e105mar/cap-1uf-100v-z5u-radial/dp/2332992

[kosacid]

I'm up and running something no one has mentioned what's the cheapest coil I'm in the uk, I have it running on a garrett 150 coil is there any cheaper coils than that

[Qiaozhi]

I'm up and running something no one has mentioned what's the cheapest coil I'm in the uk, I have it running on a garrett 150 coil is there any cheaper coils than that

The cheapest place to buy a second-hand coil is on eBay. The unbranded Chinese coil on page 128 is the cheapest new coil, again on eBay.
The only problem with the Chinese coils is that they keep changing the model number. There's one on the UK eBay site at the moment for an MD6350 at £52.79, but it doesn't state the size.
Also, there's some knock-off copies of the Fisher F2 coils.

[kosacid]

hmm I'm having problems to with the LT1054 no negative supply

[kosacid]

ok i have traced it to Q1 i replaced it now i have - voltage after R18 the signal is low i was thinking the voltage is to low for it to switch the transistor how about instead of a 10K put say a 1K just to make sure its switching ?

[Qiaozhi]

ok i have traced it to Q1 i replaced it now i have - voltage after R18 the signal is low i was thinking the voltage is to low for it to switch the transistor how about instead of a 10K put say a 1K just to make sure its switching ?

You can easily check if the sync pulse is getting to the LT1054s by connecting the scope to pin7 on either U2 or U3.

[Ronin0000]

@kosacid have you gotten it to fully work yet? If so what did you fix. Thanks, Ronin

[kosacid]

if you lift pin 7 you get negative voltage just under supply voltage, i breadboarded them but didn't test the OSC all worked fine, i got 2 that worked out of 20 chips

[kosacid]

the descriptions didn't show the first one is the OSC next is Q1 base from the Arduino clock next is the output of the chip

[kosacid]

so out of 10 chips i only got 2 working the OSC and Vref are broken or shorted i did further tests they are not fake chips just substandard when i tested them and used a external clock they work as you can see from the diagram, the working ones have saw tooth on the OSC and the Vref a steady half voltage on both them so there internal clock is working

[kosacid]

this is a working internal OSC

[kosacid]

has anyone built a 3d box for this I'm lazy and need spoon fed, i don't mind building one but if someone has it would save me time lol

[Qiaozhi]

has anyone built a 3d box for this I'm lazy and need spoon fed, i don't mind building one but if someone has it would save me time lol

The control box is quite large for a 3D printer. It would be much easier to buy an ABS plastic box from RS Components (Stock number: 1920756). The enclosure size is 60mm(H), 136mm(W), and 185.5mm(L).

[kosacid]

ok another batch of LT1054 there is something not right with this build who has actually got this build working ? there is a problem getting the negative voltage

[Qiaozhi]

ok another batch of LT1054 there is something not right with this build who has actually got this build working ? there is a problem getting the negative voltage

I can assure you that the build works perfectly as advertised.
To prove this, I have taken the attached measurements today.

1) PCB in case
2) Voltage at TP2
3) Voltage at TP3
4) Voltage at TP4
5) SYNC pulse
6) OSC pulse