Replies to Minipulse Plus

[Coolmakina]

That's a clone of the Fisher Gold Bug coil. 19kHz VLF.

Hello Mr. Carl,
Yes it is.

[Carl-NC]

That's a clone of the Fisher Gold Bug coil. 19kHz VLF.

[Qiaozhi]

Honor to you, sir.
This is the mono cool i have.
I am not near the cool, i am out for dinner.
Tomorrow i can give more details.
https://imall.com/product/Undergroun...68-20277844/en

Unless I'm mistaken, I don't think that it's a mono coil.

[Coolmakina]

And i am thinking on build some cool since i don't have the tools to measure the ones i have. Even so, i Need to understand the connections.
Thank you.

[Coolmakina]

The TX850 is a VLF metal detector, so the coil may not be suitable for a PI.
I would advise that you do your testing with a mono coil in order to keep things simple.


What are the details of this coil?

Honor to you, sir.
This is the mono cool i have.
I am not near the cool, i am out for dinner.
Tomorrow i can give more details.
https://imall.com/product/Undergroun...68-20277844/en

[Qiaozhi]

Hi Surf
I have a 11" DD from a old tx850.

The TX850 is a VLF metal detector, so the coil may not be suitable for a PI.
I would advise that you do your testing with a mono coil in order to keep things simple.

And a small gold finder
Mono cool. Bougth from Alibaba.

What are the details of this coil?

[Coolmakina]

The name of the Play List is Damping Resistor

Thank you. Appreciate that.
But, i don't understand where are you scooping.
I understand the jig, the resistors + por assembly,.
But i have no idea where you out your scoope on the second v?deo.
I am trully sorry. I am just an assh**e o thought that i could just by the boards, solder some stuff and the Child would born.
I am a self learner but this is taking me hours of living.
I can't sleep. I just read, read, read...try, try, and the more i read and try, the more i get confused.
����

[surfdetector]

Hi Dear Master Surfdetector,
i wasn't able to find your video regarding the damping resistor jig.

The name of the Play List is Damping Resistor

[Coolmakina]

What Commercial coil are you using?
The easiest way to find the correct damping resistor is to build yourself a damping resistor jig. I have a video on my Youtube channel that outlines it for you.

Hi Dear Master Surfdetector,
i wasn't able to find your video regarding the damping resistor jig.
i did found this one, regarding coil connection to pcb.
https://www.youtube.com/watch?v=PXoKiEQ8qOY
i intent to make a homemade coil, so far i get to this sketch, following your video. However, i'm not sure how to join S/F/B/G.
Can you help this NEWBIE?
Much appreciate for you time.
Best regards,

[Carl-NC]

You can make a simple square wave oscillator from a 555 timer circuit or a single opamp. Lots of info on the Internet for this.

[Coolmakina]

What Commercial coil are you using?
The easiest way to find the correct damping resistor is to build yourself a damping resistor jig. I have a video on my Youtube channel that outlines it for you.

Hi Surf
You too are so kind on helping. Thank you very much.
I have a 11" DD from a old tx850. And a small gold finder
Mono cool. Bougth from Alibaba.
I Will for sure watch your v?deo. I am a subscriber of your Channel. Thank you sir.

[Coolmakina]

Hi Mr. Carl,
Really appreciate your Patience on helping others, newbies, like me.
I ordered my suplier 470ohms. My previous post is wrong.
Thank once again.
And Thank you Also for the instructions given.
How ever i would Need a signal generator. which i don't have.
I Will try to get One.

[surfdetector]

HI good friends,
i'm stuck with step 4 of my minipulse assembly.
i'm using a comercial coil wich i don't know the inductance.
i'm using a damping resistor of 470k and my scope only registers 11V peak.
is my resistor too high?
can someone lead me to instructions, how to determine comercial coil inductance and calculater proper damping resistor?
thank you very much,
best regards,

What Commercial coil are you using?
The easiest way to find the correct damping resistor is to build yourself a damping resistor jig. I have a video on my Youtube channel that outlines it for you.

[Carl-NC]

470 ohms or 470,000 ohms? 470 might be about right, 470k is not.
If you have an oscope you can determine inductance by making a classic RL circuit and driving it with a square wave. Find the exponential tau (37% falling decay, or 63% rising decay, depending on how you measure) which is L/R. You know R so calculate L.

Once you have inductance you can put the coil in the PI circuit, remove the damping R, and look at the ringing on the oscope. The frequency of the ringing will be 1/[2*pi*sqrt(LC)]. Now you have C.

If you have L and C, the RD = 1/2*sqrt(L/C) for critical damping.

Or, put the coil waveform on the oscope and try different RD's until it looks good.

[Coolmakina]

HI good friends,
i'm stuck with step 4 of my minipulse assembly.
i'm using a comercial coil wich i don't know the inductance.
i'm using a damping resistor of 470k and my scope only registers 11V peak.
is my resistor too high?
can someone lead me to instructions, how to determine comercial coil inductance and calculater proper damping resistor?
thank you very much,
best regards,