[x] Welcome at THunting.com!

A fun place to talk about Metal Detecting, Treasure Hunting & Prospecting. Here you can share finds and experience with thousands of members from all over the world

Join us and Register Now - Its FREE & EASY

THunting.com
Treasure Hunting & Metal Detecting Community
   
Advanced Search
*
Welcome, Guest! Please login or register HERE - It is FREE and easy.
Only registered users can post and view images on our message boards.
Did you miss your activation email?

Login with email, password and session length
Or Login Using Social Network Account
2
News:
Pages:  1 2   Go Down
Print
Share this topic on FacebookShare this topic on Del.icio.usShare this topic on DiggShare this topic on RedditShare this topic on Twitter
Tags:
0 Members and 1 Guest are viewing this topic.
Offline gfrTopic starter
Copper Member
*

Join Date: Aug, 2013
Thank you7

Activity
0%

Italy
Posts: 90
Referrals: 0

535.00 Gold
View Inventory
Mac OS X 10.13
Mac OS X 10.13
Firefox 89.0
Firefox 89.0

WWW Awards

Tesoro silver uMax, Tesoro Outlaw, BFO diy.
« on: July 13, 2021, 10:16:20 am »
Go Up Go Down

Hi it's me again with a treasure hunt for.. a BFO circuit, to make a long story short...

I was reading the treasure hunting manual 7 by karl von mueller, and he talks about a circuit he found in a raytheon booklet of '50 and he built, he dub that "the little monster"

i made 2 videos on my channel about that research and construction, i will test the unit on the field as soon as i can... for now i give you pcb and schematics attached here.

the 2 videos are here:

You are not allowed to view links.
Please Register or Login

http://www.youtube.com/watch?v=sjlXn_jiidM&t=2s


You are not allowed to view links.
Please Register or Login

http://www.youtube.com/watch?v=CJyw6vsN2pQ&t=63s


let me know what you think about that

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333332.html#msg333332



There are 2 attachment(s) in this post which you can not view or download

Please register for viewing them.

pcb_and_schematic.zip
raytheon_booklet_extract.jpg


Logged
Offline nickel_n
Mod
Gold Member
*****

Join Date: Jan, 2009
Thank you356

Activity
5%
Male
Australia
Posts: 2769
Referrals: 0

6065.00 Gold
View Inventory
Windows 7/Server 2008 R2
Windows 7/Server 2008 R2
Firefox 78.0
Firefox 78.0

Awards

MXT All Pro,EagleSL,Spectrum,XLT,DFX.Garrett Seahunter markII,SD2000,GT16000
« Reply #1 on: July 13, 2021, 11:26:02 pm »
Go Up Go Down

good work
let us know how it performs on the ground Smiley

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333336.html#msg333336




Logged

The Diggers Oath
We swear by the Southern Cross to stand by each other and fight to defend our rights and liberties.

Offline gfrTopic starter
Copper Member
*

Join Date: Aug, 2013
Thank you7

Activity
0%

Italy
Posts: 90
Referrals: 0

535.00 Gold
View Inventory
Unknown
Unknown
Firefox 86.0
Firefox 86.0

WWW Awards

Tesoro silver uMax, Tesoro Outlaw, BFO diy.
« Reply #2 on: July 14, 2021, 12:14:27 am »
Go Up Go Down

Quote:Posted by nickel_n
good work
let us know how it performs on the ground Smiley


As soon as i can i will hit a wwii area with trenches... i hope the lager coil and the reduced sensitivity to little objects will be a good starting point to find big iron fragments... the frequency is high in the 1MHz range. I'll keep you informed

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333337.html#msg333337




Logged
Offline gfrTopic starter
Copper Member
*

Join Date: Aug, 2013
Thank you7

Activity
0%

Italy
Posts: 90
Referrals: 0

535.00 Gold
View Inventory
Mac OS X 10.13.6
Mac OS X 10.13.6
Safari 13.1.2
Safari 13.1.2

WWW Awards

Tesoro silver uMax, Tesoro Outlaw, BFO diy.
« Reply #3 on: July 17, 2021, 12:00:24 pm »
Go Up Go Down

for those not willing to watch videos i have updated my website too with explanation of the project etc.
I don't see the reason to fill here an enormous post so i link the page.

You are not allowed to view links.
Please Register or Login

http://gfresources.it/eresources/karl_von_mueller_little_monster.html


let me know if someone build this.
thank you

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333349.html#msg333349




Logged
Offline jhjh
Copper Member
*

Join Date: Mar, 2013
Thank you6

Activity
0%

Ireland, Republic of
Posts: 48
Referrals: 0

200.00 Gold
View Inventory
Windows 7/Server 2008 R2
Windows 7/Server 2008 R2
Firefox 91.0
Firefox 91.0

Awards

sniffer
« Reply #4 on: September 04, 2021, 05:00:34 pm »
Go Up Go Down

`nice video thank you

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333475.html#msg333475




Logged
Offline gfrTopic starter
Copper Member
*

Join Date: Aug, 2013
Thank you7

Activity
0%

Italy
Posts: 90
Referrals: 0

535.00 Gold
View Inventory
Mac OS X 10.13.6
Mac OS X 10.13.6
Safari 13.1.2
Safari 13.1.2

WWW Awards

Tesoro silver uMax, Tesoro Outlaw, BFO diy.
« Reply #5 on: September 05, 2021, 04:11:51 am »
Go Up Go Down

you are welcome, if you want make this unit I store the information plus eagle scheme and pcb here:

You are not allowed to view links.
Please Register or Login

http://gfresources.it/eresources/karl_von_mueller_little_monster.html


Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333477.html#msg333477




Logged
Offline jhjh
Copper Member
*

Join Date: Mar, 2013
Thank you6

Activity
0%

Ireland, Republic of
Posts: 48
Referrals: 0

200.00 Gold
View Inventory
Windows 7/Server 2008 R2
Windows 7/Server 2008 R2
Firefox 91.0
Firefox 91.0

Awards

sniffer
« Reply #6 on: September 05, 2021, 09:09:23 am »
Go Up Go Down

hiii

i see the ,,,.,frequency response........: 300Hz to 20KHz,,,,,

can make the frequency start ,,under 300hz,,,what coil we need Change,,,and  from where can i get the coil transformer

thank you

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333478.html#msg333478




Logged
Offline gfrTopic starter
Copper Member
*

Join Date: Aug, 2013
Thank you7

Activity
0%

Italy
Posts: 90
Referrals: 0

535.00 Gold
View Inventory
Mac OS X 10.13.6
Mac OS X 10.13.6
Safari 13.1.2
Safari 13.1.2

WWW Awards

Tesoro silver uMax, Tesoro Outlaw, BFO diy.
« Reply #7 on: September 07, 2021, 11:17:24 am »
Go Up Go Down

Quote:Posted by jhjh
hiii

i see the ,,,.,frequency response........: 300Hz to 20KHz,,,,,

can make the frequency start ,,under 300hz,,,what coil we need Change,,,and  from where can i get the coil transformer

thank you


the frequency response (you are referring to the data in my website) that you see is the one of the original UTC SSO-3 transformer, i build a transformer (20:1 like the Italian magazine version of this MD) by myself with some empiric data, with 1800 turns for the primary and 90 turns for the secondary (all 0.1mm wire), not sure of the frequency response of my transformer, but it works.

why you want change the frequency response ? this influence only your "ability" to perceive sound but I think it's irrelevant because the difference of the beat frequency (the one you can ear in the headphones) is around 1Khz, reducing this difference will increase sensitivity but increase the risk of sympathetic oscillation (frequency lock) a condition in which the detection is impossible.

in any case i try to answer to your questions:

Q: "...can we make frequency start under 300hz ?...."
A: sure we can design an appropriate transformer that is beyond the scope of this project (at least for me)

Q: what coil we need to change ?
A: the trasformer coils

Q:where can i get the coil transformer ?
A: even if I announce in the video that I propose a substitute for the original part i do not have found a proper substitute, the ones i bought where some audio 1800ohm to 8ohm transformer but they perform poorly. I think will be more convenient redesign a transistor impedance matching.. with the great gain of a silicon transistor will be easy.






Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333487.html#msg333487




« Last Edit: September 07, 2021, 11:45:50 am by giuhalftrack »
Logged
Offline jhjh
Copper Member
*

Join Date: Mar, 2013
Thank you6

Activity
0%

Ireland, Republic of
Posts: 48
Referrals: 0

200.00 Gold
View Inventory
Windows 7/Server 2008 R2
Windows 7/Server 2008 R2
Firefox 91.0
Firefox 91.0

Awards

sniffer
« Reply #8 on: September 07, 2021, 01:55:48 pm »
Go Up Go Down

mr giuhalftrack

thank you for explaining,,,

Posted on: September 07, 2021, 01:52:49 pm
i thing low frequencyis good for nugget gold

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333489.html#msg333489




Logged
Offline golddustcarl
Silver Member
*

Mood:Happy
Happy

Join Date: May, 2014
Thank you159

Activity
0%
Male
United States
Posts: 1333
Referrals: 0

7377.00 Gold
View Inventory
Linux
Linux
Chrome 88.0.4324.181
Chrome 88.0.4324.181

Awards

NOKTA SIMPLEX+,Tesoro Vaquero, VibraProbe 580, Garrett Carrot, Garrett Master Hunter ADSIII
« Reply #9 on: September 21, 2021, 11:44:39 am »
Go Up Go Down

No questions to ask. I was looking at the schematic and it brought back memories of when I was just gettin Into electronics  in 1962. The CK 722 pnp and the Ck721 NPN were the first transistors I worked with. Both were germanium transistors. The leads were very fragile and did not take to being handled too much. Lol. This circuit uses two Colpitts oscillators that are close in frequency and hetrodyned together to creat an itermediate frequency. That is what you hear in the headphones. I built my first one in 1973 but found out that it was not very good for metal detecting because I spent most of my time trying to keep it tuned to the beat frequency. Germanium transistors are very leaky and sensitive to temperature changes. A good substitute is the ubiquitous 2n3906, a silicon transistor.
Thanks for the memories, keep on with your electronics curiosty.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,72968.msg333524.html#msg333524


A bad day at gold prospecting or metal detecting is better than a good day at work.


Logged

GOLDDUST CARL

Print
Pages:  1 2   Go Up
Jump to:  

Powered by SMF 1.1.19 | SMF © 2005, Simple Machines | Sitemap
Copyright THunting.com