HAMMERHEAD REV D PROBLEM

[daverave]

I purchased a hammerhead rev d pcb from silver dog but could someone tell me if this is for the non vco version and also i need a parts list for the pcb that i have,the carl morland artical only seems to cover option 1 of an earlier pcb,im very confused can anyone pls help.

[6666]

Its on the SD site

[daverave]

what is SD ???

[Qiaozhi]

what is SD ???

SD = Silverdog.

[Qiaozhi]

I purchased a hammerhead rev d pcb from silver dog but could someone tell me if this is for the non vco version and also i need a parts list for the pcb that i have,the carl morland artical only seems to cover option 1 of an earlier pcb,im very confused can anyone pls help.

The Rev D board contains all the options mentioned in the HH article.
It's a relatively complex design to build, and you should build it piecemeal, testing each section as you go along. It's almost mandatory that you have access to an oscilloscope.

[daverave]

i have a oscilloscope but i find the carl morland parts list shown in the text not 100% applicable to the rev D pcb that i purchased from silver dog...its not a very straight forward project when it says to link out different components depending on the audio you require...wish there could have been 2 pcb's to choose from like vco or non vco...im just easily confused.

[Qiaozhi]

i have a oscilloscope but i find the carl morland parts list shown in the text not 100% applicable to the rev D pcb that i purchased from silver dog...its not a very straight forward project when it says to link out different components depending on the audio you require...wish there could have been 2 pcb's to choose from like vco or non vco...im just easily confused.

What discrepancies have you found in the parts list?
Have you started populating the PCB yet?

[daverave]

on the parts list for version 1 the resistor values only go so high...but on the revision D pcb they go up to about R55

[Qiaozhi]

on the parts list for version 1 the resistor values only go so high...but on the revision D pcb they go up to about R55

OK - I see what you mean. The parts list is only for Option 1 (it says that at the top), but there's no equivalent list for Option 2.
I think the original idea was that most people would go for Option 1, and any other brave souls who wanted to experiment could work out the differences by reading the article. I agree that the different options can be difficult to follow, but all the information is actually there if you look close enough, and it's still one of the best documented projects on Geotech.

The majority of HH builders have problems when they just throw everything on the board without understanding what each section does. Then they get in a horrible mess trying to debug it. If you take it step-by-step, we can assist with any issues you may encounter.

[daverave]

im very grateful for your help with my hammerhead...the other thing is i want to make a long slim coil to cover more ground...can i do this and if so what is the inductance of the coil ????

[Qiaozhi]

im very grateful for your help with my hammerhead...the other thing is i want to make a long slim coil to cover more ground...can i do this and if so what is the inductance of the coil ????

As I said before, you need to take this one step at a time. Test the HH with a "standard" coil (as described in the article) and later you can try a long slim coil. There is no problem doing this this, and the inductance will be the same (somewhere between 300uH and 500uH).
There are also many commercial coils that will work with the HH. Apart from PI coils from Whites and Minelab, you can also use the ones from the Garrett Sea Hunter.

[daverave]

many thanks for your help to me...as you say i will have to do a bit at a time and test as i go along...will let you know if i get any problems

[h9361]

Hello
Dear Qiaozhi
I have built HH1 Rev. C and and tested it with GPX 11" coil. I tested its damping resistor and reached to 10K. But my sensitivity still is very low. Do you think there is any tip to do for reaching high sens like TDI? I opened TDI and see that it also has used 1K for RX coil. Is any one succeed to use GPX coil over HH1 with high sensitivity?!

[Qiaozhi]

Hello
Dear Qiaozhi
I have built HH1 Rev. C and and tested it with GPX 11" coil. I tested its damping resistor and reached to 10K. But my sensitivity still is very low. Do you think there is any tip to do for reaching high sens like TDI? I opened TDI and see that it also has used 1K for RX coil. Is any one succeed to use GPX coil over HH1 with high sensitivity?!

10k is far too high for a damping resistor. The usual range is somewhere between 330R and 1k, although the damping resistor tool provides a range between 181R and 1672R.

[Carl-NC]

Hello
Dear Qiaozhi
I have built HH1 Rev. C and and tested it with GPX 11" coil. I tested its damping resistor and reached to 10K. But my sensitivity still is very low. Do you think there is any tip to do for reaching high sens like TDI? I opened TDI and see that it also has used 1K for RX coil. Is any one succeed to use GPX coil over HH1 with high sensitivity?!

As Qiaozhi said, 10k is way too high. The required RD is likely between 560 and 1000, You would need an oscope to get it just right. No, Hammerhead will probably never equal a TDI.