Surf PI Pro

[multieagle]

Is there a difference between IC L78L05 GE238 (purchased replacement) & 78L05 1122 (original kit)? I would assume anything labeled 78L05 would be the same part. Just want to eliminate that as a concern.

[multieagle]

Yes, with the 7660 removed I get a steady, adjustable threshold with no outboard motor sound, and 78L05 remains cool. However the socket voltage is 3.09v, and there is no metal detection over the coil. My battery is fully charged at 12v. If I had left it alone after you got it working for me Gary, would not be fiddling around with it at this late date. But, guess that is part of the learning process.

Gord

[chemelec]

Thanks for the feedback. The 7660 is fluctuating in the 1.5 to 2.7 range . Have ordered a new one.

If you Remove the 7660, Your +5 volts should be Stable and your 78L05 should NOT be getting HOT anymore.
Check this out.

Gary

[multieagle]

Thanks for the feedback. The 7660 is fluctuating in the 1.5 to 2.7 range . Have ordered a new one.

[chemelec]

More Likely Check the 7660.
First, See if you have the -5 volts. (Actually about 4.5 Volts)

If Not, VARIFY if Caps on the Negative Rail are Correcty placed in Polarity.

Lastly, Replace the 7660.

[Jose]

NOTE answer 1: This diode will only Protect the board, If you also have an INLINE FUSE from the Battery.

Hello Chemelec.
I totally agree with you, the truth is that we installed the diode and believe it is sufficient. Then we forget the fuse.
Thanks for the observation.
Jose

[Geo]

If 78l05 gets hot then try to replace the 5534 or 358 or 4093 or 4066 Ic's. Also check pcb for short lines.

[multieagle]

Surf PI Noise

I have been playing around with this for several months. It was my first such project, and even though I had help, and it did somewhat work (very little depth). I've changed some of the wiring and calibrated, tested components etc. With the coil attached I do get a steady background sound. However, it is completely obliterated by a loud "outboard motor" sound. And the L78L05 gets pretty hot. I've attached a short movie clip on which you can hear the sound. Perhaps someone could suggest where the problem may reside?

I've posted a short movie clip here: http://www.undergrounddetectors.ca/DSC_0002.MOV


TIA

[chemelec]

NOTE answer 1: This diode will only Protect the board, If you also have an INLINE FUSE from the Battery.

Hi Mohamed
No major changes are minor details that were made when trying to improve.
1) The protection diode can be any silicon to protect against accidental polarity change of the battery.
14) 680 ohm damping resistor, I use a 2.2K R in the coil, being in parallel the value is 520 ohm.
Different coils have different resistances, is to adapt each to better performance.
10) The resistance is 1K as the original.
11) Prea juste set to 8K 50K, for a minimum delay of 10 us.
9) "180k 47 K" = 227K" original is 240K, its exact value is not important.
7 and 8 R 51k, these resistors along with its corresponding capacitor sets the pulse width of the first and second sample, two pulses must be equal. For a reason unknown to me, there are differences between them, then one is "47 10k = 57K" and the other "47 4.7K = 51.7K", this is done by controlling the oscilloscope so that both pulses are equal in width.
Anyway not noticed any improvement with these changes.
15 and 16) 220 nF. as the original.
19) is a BC517, your connection is different to MPSA13.
17) 1 mf. Electrolyte can be.
1 is an electrolytic capacitor of 47 mF tantalum. install between "5 and -5 Volts" to improve the source filtering, but really not necessary.
"Power" This is the connection to GND aluminum foil lining the inside of the plastic housing to reduce EMI.
Everything else is the same as the original scheme except 3.3K unseen, because it is the other side of the PCB.
José

[sdesic]

Mohamed,

what happened at the end ... please share so we all can learn

[Jose]

Hi Mohamed
No major changes are minor details that were made when trying to improve.
1) The protection diode can be any silicon to protect against accidental polarity change of the battery.
14) 680 ohm damping resistor, I use a 2.2K R in the coil, being in parallel the value is 520 ohm.
Different coils have different resistances, is to adapt each to better performance.
10) The resistance is 1K as the original.
11) Prea juste set to 8K 50K, for a minimum delay of 10 us.
9) "180k 47 K" = 227K" original is 240K, its exact value is not important.
7 and 8 R 51k, these resistors along with its corresponding capacitor sets the pulse width of the first and second sample, two pulses must be equal. For a reason unknown to me, there are differences between them, then one is "47 10k = 57K" and the other "47 4.7K = 51.7K", this is done by controlling the oscilloscope so that both pulses are equal in width.
Anyway not noticed any improvement with these changes.
15 and 16) 220 nF. as the original.
19) is a BC517, your connection is different to MPSA13.
17) 1 mf. Electrolyte can be.
1 is an electrolytic capacitor of 47 mF tantalum. install between "5 and -5 Volts" to improve the source filtering, but really not necessary.
"Power" This is the connection to GND aluminum foil lining the inside of the plastic housing to reduce EMI.
Everything else is the same as the original scheme except 3.3K unseen, because it is the other side of the PCB.
José

[Mohamed Ghitas]

Here the picture of my Surf Pi, requested by Mohamed. Not very neat.
Jose[ATTACH]26392[/ATTACH]

Hi Jose, this the all difrences between you and me i figured it out check the photo



1.for protection Ok
2.iam using 1N4007
3.iam using 330 ohm
4.iam using 3.3k
5.iam using iam using 1N5817
6.iam using 5.1k
7.iam using 51k
8.iam using 51k
9.iam using 240k
10.iam using 1k
11.iam using 5.1k
12.iam using 100pf
13.iam using 1k
14.iam using 390 ohm
15.iam using 100nf
16.iam using 100nf
17.iam using 1u electrolyte
18.what is this ??
19.iam using KSP 13 same MPSA data sheet and it is reversed against yuors
20.iam using 22 ohm here
21.iam using 220k
22.iam using 100nf
23.iam using 47k
24.iam using 1k

is this is ok please tell me which one to change
Thanks in advance
Regards
Mohamed Ghitas

[Mohamed Ghitas]

Geo
The lack of sensitivity seems to be a common problem,
however I have a 10k pot for P2 and all works ok for me.


P1 = 100k [Trimmer on PCB]
P2 = 10k [Tune: Potentiometer]
P3 = 100k [Delay: Trimmer on PCB]
P4 = 1k [Volume: Trimmer on PCB or Potentiometer]

did as you say nothing changed

Hi.
I mean the potentiometer P2.
See the post of 6666.

i did but nothing changed

[Jose]

Here the picture of my Surf Pi, requested by Mohamed. Not very neat.
Jose

[Geo]

Geo
The lack of sensitivity seems to be a common problem,
however I have a 10k pot for P2 and all works ok for me.


P1 = 100k [Trimmer on PCB]
P2 = 10k [Tune: Potentiometer]
P3 = 100k [Delay: Trimmer on PCB]
P4 = 1k [Volume: Trimmer on PCB or Potentiometer]

I don't know what to say????
But now with P2=100k all are ok.
Let it as a notice for the future builders

Regards