New Hammerhead Project

[Qiaozhi]

I have measured resistance between pins 14 and 8 of microcircuit 74HCT123A. It is equal 5 Ohm. Between pins 6 and 8 of 74HCT123A the resistance is much less and equally 0,6 Ohm.
Once again
thank You
Best wishes

Here are my measurements:
pin 14 to 8 = 2 ohms
pin 6 to 8 = 1.3 ohms

These measurements were taken with an Atlas LCR meter after probe compensation.
The resistance is probably due to the package pins and internal bond wires of the 74HCT221.

[cko47]

74HCT123A in Hammer Head PI MD

May be this resistance is different for 74HCT221 and 74HCT123a. I measure with digital multimeter DT838 for IC11 and IC12. But it is for 74HCT123A a big.

[Qiaozhi]

May be this resistance is different for 74HCT221 and 74HCT123a. I measure with digital multimeter DT838 for IC11 and IC12. But it is for 74HCT123A a big.

Have you noticed any difference in operation with pins 6 and 14 externally connected to pin 8?

[cko47]

74hct123

Have you noticed any difference in operation with pins 6 and 14 externally connected to pin 8?

While it (shorting pins 14 and has not helped me to start this circuit. I search for the reason of low sensitivity this circuit (Hammer Head PI MD).
I have not two beam oscilloskope. Therefore can not determine time of the second delay rather main delay.
I do not know the switch SW2 should be the button or switch.
Thank You

[maca404]

Would you say this ground balancing worked well ? I am considering making a daughter board for my HH to incorporate your idea. At the moment It works great and detects small gold well on the bench but I live in central victorian gold field and as soon as it gets near the soil here it is basically useless.

[homefire]

Would you say this ground balancing worked well ? I am considering making a daughter board for my HH to incorporate your idea. At the moment It works great and detects small gold well on the bench but I live in central victorian gold field and as soon as it gets near the soil here it is basically useless.

Are you talking about Natural Gold or Jewelry?

Austrailian Dirt is Tough stuff.

[maca404]

Natural gold, a little .5 gram nugget. I wound a 320uh mono coil which is shielded and it decays nicely in around 8us and with a main delay around 9us it detects the nugget well. Out in the field though every movement of the coil sets it off no matter the settings, I have tried it on the beach and its quiet as a mouse so I can only assume this is a ground signature problem

[aiman197]

thank you for every one

[gef12]

Yes the Hammerhead has no Ground Balance circuit .. so is not a good unit for mineralised ground..
cheers