Hammerhead Rev. D Finish, but little problem...

[Sebastos34]

Hi, good news!
Now my IRF740 is cold, and my pcb is stable.
I replaced both 74HC221, and I think that one was not working good.
But I still have a problem... My HH only detects Medium to large Iron items.
I have nothing for a 30x4 cms alu part. It's the same for a coin.
Somebody have an Idea of my new problem? please!!!

[porkluvr]

... My HH only detects Medium to large Iron items.
I have nothing for a 30x4 cms alu part. It's the same for a coin. ...

I hope you have read Carl's article, the one with the pictures. You didn't say. My picture is taken from fig.28 of that article.

Set your controls at midway and use your scope.
If you have a dual trace scope you will only be able to see two traces at one time.

Both your sample pulses should be the same width and R45 changes the amount of time between them.
The primary sample occurs about 45us after the end of the trigger pulse (TP1).
Your sample pulses should be about 30us wide.

If you have a very old scope that shows only one trace, then I don't know what to tell you...

[Charly]

Hi,
...... the sound will be reversed (a big treble sound when no target, and the sound stops whet I put a target... )

i made also the hammerhead (board revision from 2007) and
have the same problem with the sound, no target = high sound
target = low or stopped sound, how you resolve the problem
on your board ?

best regards
Charly

[uvgunkhuu]

hammerhead pi 1

hi dear all?
i needed
hammerhead pi 1 single side pcb
high dpi picture and pdf ?
help please

[Carl-NC]

Rev C was the last single-sided version; this is a 2X layout:

[uvgunkhuu]

so much thanks for carl admin