Replies to Minipulse Plus

[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,

[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]

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.
����

[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 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/Underground-Gold-Detector-FS2-Small-Coil-5-Inch-Disk-Deep-Search-Metal-Parts-for/Tools-Measurement-Analysis-Instruments/aliexpress.com/4000004247628/568-20277844/en

[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.

[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.

[Carl-NC]

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

[Coolmakina]

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

Hello Mr. Carl,
Yes it is.

[Coolmakina]

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.

I was able to draw this scheme.
I Will try to out this in to a proto-board or so.

[Coolmakina]

Hi everyone,
i'm still stuck on this step 4 of the minipluse plus.
i started 5 units pcb, i wantend to build 5 minipluse plus. Along the way, 1 unit 79L05 was soldered backwards and still aside, It can be fixed later.
i was able to do step 1, 2 and 3 on the others 4 pcb's.
however i'm frozen at step 4.
i bought a hantek 6022be digital oscilloscope to help me out. it's not a great machine but i could afford.
the think is i don't have a large money fund to buy a decent one and a signal generator to proper calc the coil inductance and determine the damping resistor R4.
so i dig Surfdetector videos, (thanks's surfdetector!), and i built a damping jig as he described.
i also built a basket weave coil, according other threat's in this forum.
but i not reading the 350V flyback on my scope.
my probe and scope software is set to 10X, but peak to peak i only see 10,7V. and kind of a square wave trought the damping jig.
i toke some photos but i computer is crashing when i try to upload them.
is there any "check" i can make to see what is wrong with my step 4?

[Coolmakina]

Hi everyone,
i'm still stuck on this step 4 of the minipluse plus.
i started 5 units pcb, i wantend to build 5 minipluse plus. Along the way, 1 unit 79L05 was soldered backwards and still aside, It can be fixed later.
i was able to do step 1, 2 and 3 on the others 4 pcb's.
however i'm frozen at step 4.
i bought a hantek 6022be digital oscilloscope to help me out. it's not a great machine but i could afford.
the think is i don't have a large money fund to buy a decent one and a signal generator to proper calc the coil inductance and determine the damping resistor R4.
so i dig Surfdetector videos, (thanks's surfdetector!), and i built a damping jig as he described.
i also built a basket weave coil, according other threat's in this forum.
but i not reading the 350V flyback on my scope.
my probe and scope software is set to 10X, but peak to peak i only see 10,7V. and kind of a square wave trought the damping jig.
i toke some photos but i computer is crashing when i try to upload them.
is there any "check" i can make to see what is wrong with my step 4?

all parts checked and they are as spec, except that i have installed IRFS840B instead of IRF840....could this be the cause?

[Carl-NC]

IRFS840B should be fine.

[Coolmakina]

[Coolmakina]

IRFS840B should be fine.

Unless they are bad.
Seen a v?deo teste where testing with mult?meter set to diodo i shouldnt see voltage going trougth g and a of the MOSFET. Mines are ****fting voltage both ways. I think i Will replace them..
Any others ideas?