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Hi All,
Carl mentioned that the HH was designed to be used as a learning tool, or something like that. Well, he is right. A lot can be learned from a working model.
Today I was trying a few things including testing the response from a piece of basalt. I was using a mono coil at the time since they produce the greatest signal from this rock. Now, I am not going to give away what happens at this time, but I will say there is quite a difference in response from this rock when going from a maximum pulse width of about 100 usec to a minimum of about 5 usec. The same span should be tried on a small piece of gold also. The results are interesting.
Now, on a little different note, I did something a little different when connecting the external pots. I added headers and connectors. This way, the pc board can be disconnected quickly if necessary. I did use matching headers and connectors so they do sort of latch. As such, they will not fall apart without some serious effort. One can keep this in mind if they decide to do the same thing and that is most pots only need two wires, so only a 2 pin header is needed in most cases. Obviously, the threshold needs a 3 pin.
Being as lazy as I am, I elected to purchase pre-assembled connectors. Found some at All Electronics that worked fine. I have a link below displaying what I am talking about.
Now, one could get creative and find both the connectors and pre-made headers in other surplus setups if connectors are to be used, or they could build them up themselves also. Both of these methods are cheaper in the long run.
One of the advantages of this setup of being able to disconnect the pots is the fact I could swap the pulse width and freq pots which I had mounted as external controls. Now, by doing so, I can try a very long pulse length without actually having to change any parts.
If one wants to make further or wider adjustments, they can make up another pot or two with a connector and simply plug it in for a quick test. If it doesn't work as expected, just swap back.
Anyway, it is something to think about.
Reg
Two Pin Connectors
Carl mentioned that the HH was designed to be used as a learning tool, or something like that. Well, he is right. A lot can be learned from a working model.
Today I was trying a few things including testing the response from a piece of basalt. I was using a mono coil at the time since they produce the greatest signal from this rock. Now, I am not going to give away what happens at this time, but I will say there is quite a difference in response from this rock when going from a maximum pulse width of about 100 usec to a minimum of about 5 usec. The same span should be tried on a small piece of gold also. The results are interesting.
Now, on a little different note, I did something a little different when connecting the external pots. I added headers and connectors. This way, the pc board can be disconnected quickly if necessary. I did use matching headers and connectors so they do sort of latch. As such, they will not fall apart without some serious effort. One can keep this in mind if they decide to do the same thing and that is most pots only need two wires, so only a 2 pin header is needed in most cases. Obviously, the threshold needs a 3 pin.
Being as lazy as I am, I elected to purchase pre-assembled connectors. Found some at All Electronics that worked fine. I have a link below displaying what I am talking about.
Now, one could get creative and find both the connectors and pre-made headers in other surplus setups if connectors are to be used, or they could build them up themselves also. Both of these methods are cheaper in the long run.
One of the advantages of this setup of being able to disconnect the pots is the fact I could swap the pulse width and freq pots which I had mounted as external controls. Now, by doing so, I can try a very long pulse length without actually having to change any parts.
If one wants to make further or wider adjustments, they can make up another pot or two with a connector and simply plug it in for a quick test. If it doesn't work as expected, just swap back.
Anyway, it is something to think about.
Reg
Two Pin Connectors