Whites Surf PI schematic

[nelson]

HI bernte_one
Yes i understand, but i can said that all must work after i found what was damage.
I also checked 78L05, and all voltges are fine on the circuit.
On the scope i read good signal from the coil and i can adjust the delay, but the rest nothing. It looks like the problem is on the reciber stage.
i will try to send some pictures from my scope.
Thanks to all for taking the time to help me
Regards
Nelson

hello nelson would be helpful if you post a picture or set a link for picture download
the first long pcb i made had the mistake that i have changed two resistors because they lay near each other and before placing the i talk with my wife and after i stacked them changed grrrr- could tune all pots and it works but i had a bad detection range after second board i have realized the mistake because i want to do it like the first time the socond board runs fine after that i repait my first one watch also for solder that swapped over to another solder point (some solder points are nearly together could be you shorten something)

i have already finished two single sided pcb (oxygen version) but both dont work
i got a light sound but nothing happens when i couple coil and turn the pots
the 78l05...? get hot after ten seconds the oxygen board is devilish

[bernte_one]

hello mehdi thx

for q6 i use mpsa13 ( no change in position)
for q1 i use 2n3906 have it to turn 180degree (the bow shows at top)

will try it with original parts again

as you shown


if nothing goes:
if anyone sells a working singleside Pcb i would buy it (pcb with components)
the housings for long version a hard to find and to handle with the oxygenboard i could use a standard housing (plastic box) and not a pipe

[mehdi]

hello nelson would be helpful if you post a picture or set a link for picture download
the first long pcb i made had the mistake that i have changed two resistors because they lay near each other and before placing the i talk with my wife and after i stacked them changed grrrr- could tune all pots and it works but i had a bad detection range after second board i have realized the mistake because i want to do it like the first time the socond board runs fine after that i repait my first one watch also for solder that swapped over to another solder point (some solder points are nearly together could be you shorten something)

i have already finished two single sided pcb (oxygen version) but both dont work
i got a light sound but nothing happens when i couple coil and turn the pots
the 78l05...? get hot after ten seconds the oxygen board is devilish

Hi
please see the correct lay out below ( BC337 ) and change your 78L05 with new one and check the board for any short circuit.
i hope this can help

#nelson; how are you?

[bernte_one]

hello nelson would be helpful if you post a picture or set a link for picture download
the first long pcb i made had the mistake that i have changed two resistors because they lay near each other and before placing the i talk with my wife and after i stacked them changed grrrr- could tune all pots and it works but i had a bad detection range after second board i have realized the mistake because i want to do it like the first time the socond board runs fine after that i repait my first one watch also for solder that swapped over to another solder point (some solder points are nearly together could be you shorten something)

i have already finished two single sided pcb (oxygen version) but both dont work
i got a light sound but nothing happens when i couple coil and turn the pots
the 78l05...? get hot after ten seconds the oxygen board is devilish

[nelson]

Hi Apberg and all surfmaster fanatics
Today i finish my second surfmaster (long pcb), but for accident i connected C2
inverted and after i turned the unit on, C2 blows up.
So I had replaced C2 for a new one and of course I place it with correct polarity after I checked the schematic.

Now the detector is working partially.

On the scope I can see a good signal from the coil, but not sound at all, it just sounds a short tone when you turn it on, and then no sound.
Also I checked TP1 and I can regulate delay, so this stage seems to work ok.
TP2 shows nothing.
So can anyone help me find where is the problem, cause I don’t have test points for the hole circuit and my electronic skills are limited to detect what is wrong.
Has always,many thanks in advance.
Best regards
Nelson

Is possible you post here your PCB of Whites surfmaster PI ?
Thanks in advance

Dirceu

Hello Dirceu.

Made a long pcb( 2side pcb) some years ago, easy to make it waterproof. Think I made it in protel, have to sears for it. As I remember it was sometimes a litle erretic indoors. Never used it for real searsing, made only some proto's. Can send in a Pmail the pcb file (need to sears on some cd's) if you have interest in it ?

Regards.

Ap

[taliesin]

How come you all don't use the Fet like every else is?



They only cost a $!!!!

hi have a few to hand.dont like spending if i don't have to.had to bump up the damping resistor from 210 to 280 .seems to be ok.

[homefire]

How come you all don't use the Fet like every else is?



They only cost a $!!!!

[taliesin]

i've just built one.it works with tip32 but no more than 9v and it gets hot

swapped the tip32 for tip 117 works on 12v

[taliesin]

Yes! Synchronization is logical, but the another version is better. I do not know why.

mine don't work without being synced to 555

[taliesin]

No need transformer. Dump resistor is 390 ohm using IRF9640. Don't work with TIP32.

i've just built one.it works with tip32 but no more than 9v and it gets hot

[Gyur666]

Yes! Synchronization is logical, but the another version is better. I do not know why.

[bklein]

Hi! Gyur666

7660 oscillates with a 220 pF
I don't like sycronizations with power sources.

Yes! mosfet signal come from directly of pin 3 555.

Regards
DIRCEU

What exactly are the supposed benefits of running the 7660 isolated and not synchronized with the 555? The original patent for the design calls out the synchronization as one of the features of the design. Not that I like the 7660 all that much but what work was done to show this change is better? It makes more sense to me to leave it as it was.

[bklein]

Does anyone actually use the pulse delay control on these?
Anyway, thanks for the suggestions.
I tweaked mine using my old wedding ring. I set the Tuner control up a little and then played with the trimmers for max range. Sorry don't know which made what difference. But previously I had set things by scope and I gained about 3 inches detection by doing it this way. Still some motorboating in the audio that I need to pin down someday.

[dfbowers]

Jim,
I'm going to suggest that trying to measure a DC value with a string of pulses on it is not going to give you a very good idea of where your null offset is. You may get close by trial and error but your reading on a voltmeter may not be 0V. I'll check mine shortly to verify.
Don

Jim,

Just an obervation with my Surf Pi version 1.2 . It looks like the width of the pulses in the pulse train I mentioned earlier are small enough that it doesn't make a significant difference when measuring with a D.C. voltmeter. Also, I forgot that the pulses coming off of the NE5534 are opposite the flyback, so maybe cancels the measurement error a little as well.

With a DVM I measured the offset as being only .3V higher than with a scope. Measuring with the coils disconnected, only a .2V difference.

In testing, by raising the offset to +1V made a very slight difference in sensitivity. Any higher it comes at the expense of noise.
Hope this helps.
Don

[dfbowers]

Hi Guys,

I have been testing a few different coils on my surf pi and have no oscilloscope to help set them up. I have noticed that the offset of the 5534 needs to be set differently for each coil to achieve max sensitivity, and a value of 0v on the output is not necessarily best. For most of my coils the position it is most sensetive is with a DC of around 2v on the output of the 5534.

I have been monitoring the output of LM358 - pin 7 and noticed that if the voltage on this pin is any greater than 3.7v then the audio becomes dull and fuzzy and the detector stops responding to targets. Both the Delay control and the 5534 offset affect the voltage on LM358 pin 7 and I have found that the shorter the delay setting the higher the voltage. So I have tuned up by gradually setting the delay to a lower value, then adjusting the offset, then the delay again (all the while making sure the output on LM358 pin 7 stays below 3.7v) until the delay is at minimum setting and there is about 3.4v on pin 7 of the 358.

At this point the machine responds quite well to small gold rings and seems to be about as sensitive as i can make it. The DC value on the output of 5534 is anything from 0.5v to 2.5v depending on the coil.

This is a preliminary finding and i'm gonna do a lot more testing to nail this down, but in the meantime I would be interested if any of you guys could verify these results on your own detectors, make any comments or suggestions for a better methods of tuning.

I am thinking that maybe my coils are a bit wide of the desired inductance and hence the need to set the offset away from 0v ?????????

Regards Jim.

Jim,
I'm going to suggest that trying to measure a DC value with a string of pulses on it is not going to give you a very good idea of where your null offset is. You may get close by trial and error but your reading on a voltmeter may not be 0V. I'll check mine shortly to verify.
Don