Surf Pi Pro Build

[cddz]

hello cddz,

nice build, which type of Hammond enclosure do you use 1455xx?
at first look i think the is enough space too but one pack o 3*18650 with internal charger bord you could add a siwtch on/off/on to selct between detector on or charger on
http://www.ebay.de/itm/4A-5A-PCB-BMS...kAAOSwrklU9BHK

I picked this enclosure up a couple of years ago for another project that I did not complete. http://www.mouser.com/Search/Product...46-1455N1601BK

I had thought about placing the batteries inside, just figured I would use what I had on hand for the power supply.

[eclipse]

I'm using the very same enclosure. Accommodates 100x100 PCB + 4x LI-ION pack and all front/back panel gizmos. Mounted on a whites metal detector shaft.

[cddz]

Riddle me this. 4.7k dampener resistor for this. Something must be wrong again . Although the delay setting seems to work now. I can pick up a .5 gram piece of gold at 4.5 inches, is that good?

[daverave]

i have found a damping resistor between 390 - 450 ohm is correct for the surf pi.

[Qiaozhi]

Riddle me this. 4.7k dampener resistor for this. Something must be wrong again . Although the delay setting seems to work now. I can pick up a .5 gram piece of gold at 4.5 inches, is that good?

This might seem an obvious (or even stupid) question ... BUT, are you sure it's actually a 4k7 and not a 470R?

[jladre]

It is impossible that this machine work good with 4k7 resistance, its too high..

[Teleno]

The Surf PI Pro has no current limiting, so the coil current will depend on its inductance.

The timing is as follows:

Ton = 50.5 us
Toff = 1.6 ms
Freq = 615 Hz

If you measure the parasitic capacitance of your coil you can play with the attached LTSpice simulation.

[Teleno]

Replacing MOSFET IRF9640 (200V) by FQP3P50 (500V) can gain you 3 us.

http://nl.mouser.com/ProductDetail/F...75ib961Q%3d%3d

[junkhunter]

Nice job cddz and i have better success with a lose wound coil .Also can you swim under water with it .there is a challenge

[cddz]

This might seem an obvious (or even stupid) question ... BUT, are you sure it's actually a 4k7 and not a 470R?

It is 4k7, not 470R.
I am not sure what is going on with it, I couldn't get it to ring at all so I took the parallel resistor off the tool.
Going to take another look over the board, I must have done something when I removed it from the enclosure last night.

[kt315]

question

[cddz]

question

[ATTACH]34918[/ATTACH]

I had the headphone jack polarity wrong, shorted to +B. Removed and tested resistor and it still tested at 12 ohm. It is on my list Audio still sounds good

[cddz]

Okay,
I figured out the high Dampener resistor reason.
I was using http://www.ebay.com/itm/High-Quality...-/281745576948 to shield the coil. With that removed the best value is now 670.
Noob mistake I guess. I plan to use carbon paint to shield the coil once i get my shell.

[Darin]

I have the same board. Got mine assembled. The delay never really work to start with. Worked ok with a cheap coil I had made but not much depth, I blamed the coil for that but it did work on my MPP not great but did work. I set mine in a plastic box then took it out latter and it was dead. Replaced NE5534 and LM358 to get it working then the sound started going in and out resoldered R34 sound is back but detector still needs work I'm learning so its slow going.

[cddz]

I have the same board. Got mine assembled. The delay never really work to start with. Worked ok with a cheap coil I had made but not much depth, I blamed the coil for that but it did work on my MPP not great but did work. I set mine in a plastic box then took it out latter and it was dead. Replaced NE5534 and LM358 to get it working then the sound started going in and out resoldered R34 sound is back but detector still needs work I'm learning so its slow going.

My first coil was not good and caused me to scratch my head a bit, said to hell with it and wound a spiral coil with some 22 awg 7/32 appliance wire, this coil is a keeper Not sure why my delay was not working before, maybe the first coil was junk. I did have to reverse the wire on the pot to get it increasing in the correct rotation.