My take on the HH2

[waltr]

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)?
[ATTACH]55359[/ATTACH]

Not sure you will need to build and try it. I don't think this will drive an 8 Ohm speaker but maybe a higher impedance speaker.

Due to case at 0V (B+) and audio out referenced to B-, I put a audio transformer, 1k:8 Ohm where the schematic indicates head phones.
The transformer output then drives a low latency Blue Tooth transmitter.
I wrote about this above.

[h9361]

Not sure you will need to build and try it. I don't think this will drive an 8 Ohm speaker but maybe a higher impedance speaker.

Due to case at 0V (B+) and audio out referenced to B-, I put a audio transformer, 1k:8 Ohm where the schematic indicates head phones.
The transformer output then drives a low latency Blue Tooth transmitter.
I wrote about this above.

Thanks dear Walter.
Actually, i'm going to build and to test three versions of Audio for my HH1: your audio, Mr. Mdtoday and the attached.
After testing, i will tell you my results.
Is it possible to see the attached, is it correct?

[waltr]

Thanks dear Walter.
Actually, i'm going to build and to test three versions of Audio for my HH1: your audio, Mr. Mdtoday and the attached.
After testing, i will tell you my results.
Is it possible to see the attached, is it correct?
[ATTACH]55365[/ATTACH]

Build it to find out. And like I said, it can depend of which speaker you use.

Why don't you start a new thread in the HH1 sub-forum for all your questions and the results of your builds and tests.
Then it is all in one thread instead of scattered through out the geotech forum and in the wrong threads.

[h9361]

Build it to find out. And like I said, it can depend of which speaker you use.

Why don't you start a new thread in the HH1 sub-forum for all your questions and the results of your builds and tests.
Then it is all in one thread instead of scattered through out the geotech forum and in the wrong threads.

Thanks.
I will create the HH1-sub-Forum soon.
See attached, i think it's more easier than other method for 8R speaker.

[waltr]

Thanks.
I will create the HH1-sub-Forum soon.
See attached, i think it's more easier than other method for 8R speaker.
[ATTACH]55387[/ATTACH]

The LM358 is easy to use and drives an 8Ohm speaker. So that is a viable way to go.
Looking forward to your thread and what you find building and testing.

[h9361]

The LM358 is easy to use and drives an 8Ohm speaker. So that is a viable way to go.
Looking forward to your thread and what you find building and testing.

Thanks dear Walter.
Today, i built two coils, 45 and 22 cm (500uH with 0.35mm wire) for my HH1 (Non-VCO, version C2). According to your advise, i connected my O-Scope to TP4 and made the damping tool (suggested in IMD book). My best result was with 680R damping but i still have a significant problem with sensitivity. Unfortunately, my 45cm can detect a silver ring at 0.5 cm distance, a steel 20x30 cm from 35cm!!!! My 22cm coil has the result too, i don't know where my problem is. Since you have a lot of experience about HH, do you have any suggestion for check?
Before starting my new HH1+GB and making a new thread, i'm trying to find my problem. Then, i solve it over my new schematic or new board.
Thanks.

[h9361]

Thanks dear Walter.
Today, i built two coils, 45 and 22 cm (500uH with 0.35mm wire) for my HH1 (Non-VCO, version C2). All of my tests was that based on a 9cm coil with 500uH with 680R damping+0.35 wire. According to your advise, i connected my O-Scope to TP4 and made the damping tool (suggested in IMD book). My best result was with 680R damping but i still have a significant problem with sensitivity. Unfortunately, my 45cm can detect a silver ring at 0.5 cm distance, a steel 20x30 cm from 35cm!!!! My 22cm coil has the same result too, i don't know where my problem is. Since you have a lot of experience about HH, do you have any suggestion for check?
Before starting my new HH1+GB and making a new thread, i'm trying to find my problem. Then, i solve it over my new schematic or new board.
What is interesting is that all of my coils (9cm, 22cm, 45cm) have the same result with identical distance!!!! Off course, i saw all of them in O-scope and measured its damping (500uH, 680R).
Thanks.

[waltr]

Need more info.
What is the TX pulse length?
Sample Delay, sample timing, etc.

Take scope pictures of timing.

Damping R of 680 Ohm sounds about right for a simple 500uH coil.

35cm for a steel object is good. 1/2 cm for a silver ring in not.
What is the size and shape of steel object????
We typically use coins for testing since they are standard size, shape and material.
In the EU a 1 euro coin at 30-35cm is considered good.

I found that a US Silver quarter responded better with a 200us TX pulse and a 100us pulse.
This is due to it longer TC that needs a longer tx on time to fully allow eddy currents to die out before TX off.
This also means that the return eddy current are longer and a longer sampling gives a bigger signal.

Is there ANY local EM for Mains powered equipment???

You really need to go stage by stage with the scope and see what the signals look like.
Could be many reasons.

[h9361]

Need more info.
What is the TX pulse length?
Sample Delay, sample timing, etc.

Take scope pictures of timing.

Damping R of 680 Ohm sounds about right for a simple 500uH coil.

35cm for a steel object is good. 1/2 cm for a silver ring in not.
What is the size and shape of steel object????
We typically use coins for testing since they are standard size, shape and material.
In the EU a 1 euro coin at 30-35cm is considered good.

I found that a US Silver quarter responded better with a 200us TX pulse and a 100us pulse.
This is due to it longer TC that needs a longer tx on time to fully allow eddy currents to die out before TX off.
This also means that the return eddy current are longer and a longer sampling gives a bigger signal.

Is there ANY local EM for Mains powered equipment???

You really need to go stage by stage with the scope and see what the signals look like.
Could be many reasons.

Very thanks.
As you know, TX pulse of HH1 is between 10 and 75 us. I think my problem is the range, a user that has been able to make a big coil (90cm) suggest me to change TX pulse to 50-400us.
He changed C8 value and could get a good response for 90cm coil. For exp, he can detect a 30cm Cast iron plate from 150cm!

[6666]

Very thanks.
As you know, TX pulse of HH1 is between 10 and 75 us. I think my problem is the range, a user that has been able to make a big coil (90cm) suggest me to change TX pulse to 50-400us.
He changed C8 value and could get a good response for 90cm coil. For exp, he can detect a 30cm Cast iron plate from 150cm!

This is from early in the thread
100us TX (with a 10 Ohm series R to coil), 8-15us delay1, 15us samples & 34us delay2.

[surfdetector]

Build it to find out. And like I said, it can depend of which speaker you use.

Why don't you start a new thread in the HH1 sub-forum for all your questions and the results of your builds and tests.
Then it is all in one thread instead of scattered through out the geotech forum and in the wrong threads.

@ h9361, It really would be better if all of this was moved to the Hammerhead 1 section. The HH2 section is now getting way off topic.

[h9361]

Dear Walter
I changed value C8 to 47n, so my TX Pulse will be 55-400uS and Freq. 400 -1818.
Today, i tested it over my coil, but i have still very very poor depth. For exp, i can detect a nickel coin from 1/2 cm!!!
Unfortunately, my O-scope is a mini-portable with one channel, so i have to take photo from one channel.
I doubt to C10 and R10. Now, i'm using a 12V-1A sealed acid battery, do you think it's for them?!

[h9361]

Hello
Dear Walter
I have a question about your R39 or R23 HH1.
Unfortunately, i have to make a new HH1 but i have a problem with R23. My R18 works nice but R23 has not any affect over Pin 2,3 of IC8.
Do you have any suggestion?
Thanks

[waltr]

Hello
Dear Walter
I have a question about your R39 or R23 HH1.
Unfortunately, i have to make a new HH1 but i have a problem with R23. My R18 works nice but R23 has not any affect over Pin 2,3 of IC8.
Do you have any suggestion?
Thanks

Duplicate post and wrong thread for HH1:
https://www.geotech1.com/forums/show...000#post289000

[h9361]

Hello
Dear walter
I have a question about flyback voltage at tp2.
According to Mr. Carl's paper, his flyback voltage is between 100 and 300v. Do you think size of a coil can change the voltage? For exp, i tested it over my 9cm coil and it is 46vpp. Do you think it is normal? I also check my r11 and saw it is a bit warm.