My take on the HH2

[h9361]

Very thanks dear Walter.
Please see the attached, it's your Audio Part. I want to change your audio to pitch ... pitch (general pulse induction Audio, exactly like VCO in HH1).
Do you think i can reach it if i remove R50, or it doesn't need any change?

[waltr]

Very thanks dear Walter.
Please see the attached, it's your Audio Part. I want to change your audio to pitch ... pitch (general pulse induction Audio, exactly like VCO in HH1).
Do you think i can reach it if i remove R50, or it doesn't need any change?
[ATTACH]55252[/ATTACH]

If you remove R50 then the 555 will not oscillate.
Build that circuit and give it a try.

[h9361]

If you remove R50 then the 555 will not oscillate.
Build that circuit and give it a try.

Please forgive me for bad writting.
My mean is direct connection R52 to Q10 and removing R50.

[waltr]

Please forgive me for bad writting.
My mean is direct connection R52 to Q10 and removing R50.

That should change the Frequency the 555 oscillates at. It may or may not work the way you wish. Build the circuit and try.
Also Web search 555 circuits, there is a tons of them, to learn how a 555 works. Go through the calculations of different resistance for R5/Q10 and see if the 55 oscillates at the frequency you wish.

In the HH circuit the JFET, Q10 acts as a variable resistor which changes the total resistance (in series with R50).

[h9361]

Hello
Dear Walter
I want to know your opinion about GB process.
Suppose that i want to use GB using four delays, A1(S1-S3) - A2(S2-S4).
As you know, variable A2 can act as GB. Similarly, suppose that i set gain 200 for A1. In this case, what value do you suggest me for A2? for exp, putting 200 or more than 200?!
Thank you

[Carl-NC]

Suppose that i want to use GB using four delays, A1(S1-S3) - A2(S2-S4).
As you know, variable A2 can act as GB. Similarly, suppose that i set gain 200 for A1. In this case, what value do you suggest me for A2? for exp, putting 200 or more than 200?!

It depends on the width of S2. A2 can be less, more, or the same depending on S2. When you build it you will quickly see what happens.

My earlier questions still linger:

Do you know how to read data sheets?

Do you have any electronics knowledge?

Have you ever built any circuits?

Do you have an oscilloscope?

These are critical skills if you are going to have any chance of success.

[h9361]

It depends on the width of S2. A2 can be less, more, or the same depending on S2. When you build it you will quickly see what happens.

My earlier questions still linger:

Do you know how to read data sheets?

Do you have any electronics knowledge?

Have you ever built any circuits?

Do you have an oscilloscope?

These are critical skills if you are going to have any chance of success.

Thanks dear Carl for your guiding.
My main expertise is Software Engineering (M.SC certificate) and i'm trying to get my PHD in this field.
But beside of my expertise, i'm interesting to learn more about Electronic, especially about PI technology.
During my research, i found your HH1 article and learned more about PI method. So, i decided to test it practically. My first trying was HH1 (non-VCO) and it works very nice.
Now i have to thank you for your best article. For more learning, i bought your book IMD (electronic version) and read its PI part. The book is the best for everyone that is interesting to learn more about metal detector.
For building your HH1, i had to buy a portable O-Scope (mini) and now i'm using it. Now, i'm going to build HH1 based on Mr. Walter's schematic + FourDelay + Mr. Mdtoday's Audio.
So before building, i'm trying to understand my possible problems. Please forgive me for my amatory questions.

[h9361]

Hello
Dear Walter.
Please forgive me for my questions.
See attached, it's Mr. Mdtoday's Audio schematic.
Unfortunately, quality of the pic isn't good. Can you tell me value of C8 (2.2uF or 22uF) and VR1-Pot?
Thank you.

[6666]

Hello
Dear Walter.
Please forgive me for my questions.
See attached, it's Mr. Mdtoday's Audio schematic.
Unfortunately, quality of the pic isn't good. Can you tell me value of C8 (2.2uF or 22uF) and VR1-Pot?
Thank you.

On Mick's original hand drawn circuit its 2.2uF and 100K

[Carl-NC]

Thanks dear Carl for your guiding.
My main expertise is Software Engineering (M.SC certificate) and i'm trying to get my PHD in this field.
But beside of my expertise, i'm interesting to learn more about Electronic, especially about PI technology.
During my research, i found your HH1 article and learned more about PI method. So, i decided to test it practically. My first trying was HH1 (non-VCO) and it works very nice.
Now i have to thank you for your best article. For more learning, i bought your book IMD (electronic version) and read its PI part. The book is the best for everyone that is interesting to learn more about metal detector.
For building your HH1, i had to buy a portable O-Scope (mini) and now i'm using it. Now, i'm going to build HH1 based on Mr. Walter's schematic + FourDelay + Mr. Mdtoday's Audio.
So before building, i'm trying to understand my possible problems. Please forgive me for my amatory questions.

OK, that's all good to know. Many of your questions are easily answered by simply building the circuit, so it left me with the impression you have not built any circuits. Other questions you have asked suggested you don't understand electronics, which may be true. Both of these are solved by hands-on experience: build circuits and learn! If you can get one, I suggest a plug-in style breadboard as seen on page xi in ITMD. You can then easily change the circuit and re-use components.

[h9361]

OK, that's all good to know. Many of your questions are easily answered by simply building the circuit, so it left me with the impression you have not built any circuits. Other questions you have asked suggested you don't understand electronics, which may be true. Both of these are solved by hands-on experience: build circuits and learn! If you can get one, I suggest a plug-in style breadboard as seen on page xi in ITMD. You can then easily change the circuit and re-use components.

Thanks dear Carl.
First i used breadboard. Then, my friend helped me to build it as through hole mode (Off course, now i learned how to assemble as through hole mode ).
Anyway, since i joined to this forum, i read all of Posts that belonged to HH1 and GB processing. According to your guiding and answer of my questions (by Mr. Walter, Mr. Mdtoday and...), i have drawn a new possible schematic for using GB (four delays). I hope my understand be correct and you confirm it. Mr. Carl, can i send my schematic to your Email?
Thanks.

[h9361]

On Mick's original hand drawn circuit its 2.2uF and 100K

thanks.

[h9361]

Hello
Dear Walter
Since you have a lot of experience about metal detectors, i have to ask you. Please forgive me for my questions.
I want to shield my coil for electromagnetic noise. My first selection is use of Graphite spray, do you think i can use it instead of foil (copper or aluminum) ?

[waltr]

Hello
Dear Walter
Since you have a lot of experience about metal detectors, i have to ask you. Please forgive me for my questions.
I want to shield my coil for electromagnetic noise. My first selection is use of Graphite spray, do you think i can use it instead of foil (copper or aluminum) ?

There is a lot of discussion here on Geotech about shielding methods.
Graphic is an option. SEARCH and READ the forum for more insight.

[h9361]

OK, thanks dear Walter.
I have a question about your Audio part. Do you think i can use a speaker or need to an audio amplifier (LM386)?