Hammerhead Rev D discussions

[cko47]

Are using the correct value of damping resistor? It looks like the coil is underdamped.

Than You for your quick reply.
The damping resistor R11 is 1 kom.
The bottom peak on the image (in time) lays somewhere within the limits of 30-40 microseconds. It it is too much for search of gold nuggets of the small size. I shall try to reduce the mentioned resistor (R11) up to 680 om

[Qiaozhi]

Hi!
Using my program (for digital processing) I get the following image at TP4. At it is visible oscillation of coil. How is reason this? May be capacitance of IRF740 or coil?

Are using the correct value of damping resistor? It looks like the coil is underdamped.

[cko47]

HammerHead PI

Hi!
Using my program (for digital processing) I get the following image at TP4. At it is visible oscillation of coil. How is reason this? May be capacitance of IRF740 or coil?

[6666]

Were the details for the DD coil ever published ?
I have not been able to locate the text which talks about this option.
I know its a few years old now
thanks
6666

[moe]

THANKS "bbsailor"

Thanks for pointing me in the right direction....Frequency is 900HZ...It was a type o. Looking forward to posting my experiences and a photo of my finished HHD1 Detecor.
Regards,

Moe

[bbsailor]

First of all..HELLO to everyone in this forum. I found you guys just googling around, next I know I have my HammerHead Detector board in front of me!!
I think I have populated the board with all the correct parts, double checked it to make sure....when I turn it on...I have a very high audio and Q11 gets hot...also the Audio pot!!.. I have my frequency set at 900KHZ and pulse width is 70us. Could someone who has successfully built one, help me out with any part change (value wise) or mods that must be added.
I thank you in advance.

Moe,

First. The frequency range is 900 Hz to about 2500 Hz not 900KHz.

Second. The reason that Q11 is getting hot is that I suspect you are using a metal case with a headphone jack that is mounted directly to the metal. If this is the case, just remove the headphone jack from the metal case and wire a temporary in line jack or isolate the jack from the metal with non-metalic shoulder washers. The key is to not ground the heaphone jack to the metal case. You may need to replace Q11 and the volume pot.

Once you get the basic circuit working, you can then ask specific questions about modifying it for your particular application.

The Hammerhead Rev D is a good learning platform that has already incorporated may forum member recommended improvements. Read Carl's article describing the original Hammerhead project and check his web postings to see how the Rev D was upgraded. He has not updated his article to reflect the Rev D circuit board. Compare your populated circuit board to photos posted by others who built the Rev D. Hammerhead circuit board. Double check the resistor values and transistor orientions.

To probe the depths of the Hammerhead, you will need access to an oscilloscope. There are test points (TP) on the circuit board to help troubleshoot the circuit or observe what is happening then you modify some key timing components.

bbsailor

[moe]

PROBLEM WITH MY HHD BOARD...

First of all..HELLO to everyone in this forum. I found you guys just googling around, next I know I have my HammerHead Detector board in front of me!!
I think I have populated the board with all the correct parts, double checked it to make sure....when I turn it on...I have a very high audio and Q11 gets hot...also the Audio pot!!.. I have my frequency set at 900KHZ and pulse width is 70us. Could someone who has successfully built one, help me out with any part change (value wise) or mods that must be added.
I thank you in advance.

[Qiaozhi]

Hi, is it possible someone to share the Gerbers for HHd and the part list ?
Thanks a lot!!

http://www.geotech1.com/cgi-bin/page...head/index.dat

[zpe]

Hi, is it possible someone to share the Gerbers for HHd and the part list ?
Thanks a lot!!

[rajesh]

7660

hi I have found that The ICL7660CPA, Absolute
Maximum Rated at 10.5 Volts, Works just fine, even when the battery is Fully
charged at 14.5 volts!



There is a ICL7660ACPA which has an Absolute Maximum Rating of 13 Volts,
These test the same as the ICL7660CPA!


Additionally there is a ICL7662CPA with an Absolute Maxium Voltage Rating of
22 Volts. It appears to be about 1/2 the price of the LT1054.

The LT1054 costs 4 times or More than the price of either of the ICL7660's!
A BIG DIFFERENCE!

[rajesh]

ne 5534

dear sir carl
i think tl081 opamp is good for place ic 6 i dont know why not use it.

[Carl-NC]

Just remindering, where is ?
Danke

Gerber & GIF files are now posted.

On Rev C, I posted a GIF layout and the Gerber files. I need to do that for Rev D, and I will. However, I'm on the road right now, so it will be ~ 2 weeks.

- Carl

Just remindering, where is ?
Danke

[ruud]

1 or 2 coils switch

Because I will using a 1 or 2 coil sensor, i will using a extra switch S3 , see image.
Any comments?

[Carl-NC]

thanks! But the link shows the placement, if I want to etch my own PCB I need a raw layout without any printed parts. Or am I wrong?

On Rev C, I posted a GIF layout and the Gerber files. I need to do that for Rev D, and I will. However, I'm on the road right now, so it will be ~ 2 weeks.

- Carl