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  #26  
Old 01-11-2018, 08:05 AM
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Quote:
Originally Posted by abdou2014 View Post
Is the preamp necessary ?
I believe yes.
Esteban was telling that one friend of him found a big silver "treasure" without the use of preamplifier. The commercial lrl use preamp
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  #27  
Old 01-11-2018, 08:13 AM
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Originally Posted by brs View Post
Hi Geo
has certainly worked on this machine and its results are satisfactory
Hi.
i constructed it long many years ago (maybe 10+) with all mods and adds.
Results at my area was not good. It located only some small objects from short distance.
I keep it yet
It is a good way for someone to construct a lrl and play with it with little money, compared with the money that has the commercial
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  #28  
Old 01-11-2018, 08:25 AM
abdou2014 abdou2014 is offline
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Thank you Mr Geo :

I want to put only one JFET, is it better ?

what is your advice (BF 245 OR 2N3819) ?

I know you do not like working with 59 Khz, what do you recommend me ( 80Khz or 85Khz ) ?
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  #29  
Old 01-11-2018, 08:37 AM
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The basic is to put the preampl inside the coil. Also a potentiometer to control the gain of preamp is neccessary. I don't know who freq is the best for your area. Play with all by changing the tuning capacitor. I prefer 80 ... 100Khz.
I attach a photo from the head of my lrl...
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  #30  
Old 01-11-2018, 09:22 AM
abdou2014 abdou2014 is offline
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Thank you !
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  #31  
Old 01-11-2018, 10:24 AM
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Between the preamp and The Amplifier IC1, what are the changes for (C1 - R3) ?
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  #32  
Old 01-11-2018, 10:54 AM
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Quote:
Originally Posted by abdou2014 View Post
Between the preamp and The Amplifier IC1, what are the changes for (C1 - R3) ?
Make C1= 47n and connect a resistor 1M between pin2 and ground (IC1a)
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  #33  
Old 01-11-2018, 11:34 AM
abdou2014 abdou2014 is offline
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I'm designing the circuit board . Thanks for your help
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  #34  
Old 01-11-2018, 11:56 AM
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For the coil I think a big inductor is more sensitive except that it may react to interferences,

what is the best Coil for this device ?
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  #35  
Old 01-11-2018, 09:56 PM
Mike(Mont) Mike(Mont) is offline
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Happy Birthday Geo!

Looks interesting enough to experiment with.
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  #36  
Old 01-12-2018, 01:42 AM
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Hi folks, I build an lrl based on the original schematic of Andy with some modification that is more sensitive and directional. Pre-amp is still used, values of the components like capacitors and resistors are changed, audio stage are also changed, Ic's are also changed which make this lrl very reliable to use.
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  #37  
Old 01-12-2018, 08:55 AM
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That's what I'm doing, you want to help or scare ???
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  #38  
Old 01-12-2018, 12:26 PM
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In place of speaker you can use a beep generator.
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  #39  
Old 01-12-2018, 12:54 PM
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we connect the audio output directly in the 555, or we add 100nF + transistor between two

resistor 680K ?
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  #40  
Old 01-12-2018, 03:06 PM
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Do you have the schematic of Alonso's PD???
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  #41  
Old 01-12-2018, 03:10 PM
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Quote:
Originally Posted by Mike(Mont) View Post
Happy Birthday Geo!
Thanks Mike and Sneshko
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  #42  
Old 01-12-2018, 06:08 PM
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We have to change nothing in the original diagram except C1 - R3, you confirmed ?
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  #43  
Old 01-12-2018, 06:12 PM
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I think (mineoro special series 2000 and Iconos md) are prototipe Andy flind modified ?
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  #44  
Old 01-12-2018, 07:25 PM
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Quote:
Originally Posted by abdou2014 View Post
I think (mineoro special series 2000 and Iconos md) are prototipe Andy flind modified ?
No....
I asked you if you have shematic of PD????
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  #45  
Old 01-12-2018, 07:40 PM
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Quote:
Originally Posted by abdou2014 View Post
We have to change nothing in the original diagram except C1 - R3, you confirmed ?
you will see on the way...
It is better to make a pcb only for beep generator and another one for coil preampl.
Also it is better to use different power supply for beep generator and for preampl.
Only you will see the problems and what mods to make...
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  #46  
Old 01-12-2018, 08:02 PM
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I'm sorry, I have clone Alonso-PD schematic ,
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  #47  
Old 01-12-2018, 08:17 PM
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Quote:
Originally Posted by Geo View Post
Hi.
All these years i received so many mails to post the schematic of Andy Flind.
Today i decided to post it here.
Article is in PDF format and it is from EPE magazine.
I would like Admin to tell me if i can do it or No. Article is from year 1995.

Regards
Thanks Geo

for me, one of the best lrl
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  #48  
Old 01-13-2018, 08:40 AM
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Hi Chris, how are you.
Try this project, maybe to have good results at your are.
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  #49  
Old 01-13-2018, 08:46 AM
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Quote:
Originally Posted by abdou2014 View Post
I'm sorry, I have clone Alonso-PD schematic ,
So you can use the beep generator from PD. A 100nf at input is ok.
Try to connect it to output of IC4.
IC5 is a tone generator, we don't need it because beep generator uses beeper with internal oscillator.
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  #50  
Old 01-13-2018, 05:04 PM
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Thank you Geo !

Beep generator from PD !
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