IDX-PRO+VDI

[Koala]

very hard
i do it , just have 7.1volt p-p for my cc coil for TX.
TX 32turn 0.7mm wire in 20cm circle(510mkh)
RX 443 turn in 8.6cm circle 0.2mm(34.7mh and 78 ohm),directly connect to board
BX 12turn around RX .by 0.2mm wire(start connect to finish TX )then start of TX and finish of BX get to board.
i do your guid mr gulfnut but just have 7.1volt ,when i remove BX coil and connect directly Tx coil to the board have 12to14 volt p-p or derease cap parralel TX and have mor voltage, why???
regards
i go college and two days i am not here .
regards

Have you seen the instructions here

nulling here

[golfnut]

I have only made one O-O type and the result was OK but not great - I had too many Rx turns and it got bulky and ugly. Your question,,,,, " have 7.1volt ,when i remove BX coil and connect directly Tx coil to the board have 12to14 volt p-p" This is normal - as the buck is wound to opposite way the current flow thru it is the opposite direction and the volts across it are -ve WRT to the Tx coil. From your measurement of Tx only you got 12 with the buck in series you got 7 AS 12-5=7

[mohandes]

I have only made one O-O type and the result was OK but not great - I had too many Rx turns and it got bulky and ugly. Your question,,,,, " have 7.1volt ,when i remove BX coil and connect directly Tx coil to the board have 12to14 volt p-p" This is normal - as the buck is wound to opposite way the current flow thru it is the opposite direction and the volts across it are -ve WRT to the Tx coil. From your measurement of Tx only you got 12 with the buck in series you got 7 AS 12-5=7

ok so what am i doing by cc coil ? remowe the BX coil ?or what???please guide
i do like MR Dfbowers and that like your put it here Mr koala.

[golfnut]

No, my reply was the answer to your question.




You need a buck coil to get a null with a cc type. The buck is wound in the opposite direction to the Tx.


Without a buck the Rx coil would pick up masses of Tx signal. _( Unusable )-

The buck coil generates some field in the opposite sense to that of the Tx coil - So the Rx coil ends up picking up 0 Tx signal as Plus Tx feild with minus Buck feild = 0 Rx feild

Don is the man for the CC coil..

S

[mohandes]

No, my reply was the answer to your question.




You need a buck coil to get a null with a cc type. The buck is wound in the opposite direction to the Tx.


Without a buck the Rx coil would pick up masses of Tx signal. _( Unusable )-

The buck coil generates some field in the opposite sense to that of the Tx coil - So the Rx coil ends up picking up 0 Tx signal as Plus Tx feild with minus Buck feild = 0 Rx feild

Don is the man for the CC coil..

S

thanks guru
ok i am more trying

[mohandes]

CC or DD or OO coils
which better work for this detector???????????????
i make DD and good and CC is hard and not good but just OO coil REMAINDER ?
any one can say me any inormation?

[Koala]

I prefer the 27 cm DD on nice even ground and a stock 8" cc on difficult ground don't have OO.

DD bigger coil more depth better coverage. 8" more stable marginally better pinpointing, less depth which is sometimes good. Nearly always use the 8" on the dry/damp beach and DD on land. DD works very well on the very dry sand the kind that just falls through your fingers. Digging 30+ cm down can be slow going though.

[wlewis]

Is there a way to test the pcb without hooking it up to a coil?

[golfnut]

You can test the supplies. and the audio oscillator. you can pull the 4066 mixer and feed an 8Hz tone into the filter amps at low level to check for gain. Similarly you can feed a 6kHz tone into the preamp at low level and observe the gain. If you had a 6kHz signal source which you could get about 15Vpp from like a wien bridge into an audio xfmer to get to 15Vpp - this could be attached to the geb and disc phase shifters to see the gating clock the mixers - you may have to cut the trace from Q1 collector to coil - so your not driving the Tx osc in reverse. S

[wlewis]

You can test the supplies. and the audio oscillator. you can pull the 4066 mixer and feed an 8Hz tone into the filter amps at low level to check for gain. Similarly you can feed a 6kHz tone into the preamp at low level and observe the gain. If you had a 6kHz signal source which you could get about 15Vpp from like a wien bridge into an audio xfmer to get to 15Vpp - this could be attached to the geb and disc phase shifters to see the gating clock the mixers - you may have to cut the trace from Q1 collector to coil - so your not driving the Tx osc in reverse. S

supplies.. check. what do you mean pull the 4066? Should i expect a squarewave coming out of tx? You mean inject a low level signal into rx? I do have a signal source btw. Can you go over some theory? Post #612 on pg 25 has some theory on the tx but has anybody posted the overall theory of the circuit? Isnt the mpsa13 kinda small to pump out a good signal? How to feed an 8hz into the filters.. where? Also.. R41 at 220R attenuates for phones right? I dont see the option for phones on sikverdog's board.

[mohandes]

supplies.. check. what do you mean pull the 4066? Should i expect a squarewave coming out of tx? You mean inject a low level signal into rx? I do have a signal source btw. Can you go over some theory? Post #612 on pg 25 has some theory on the tx but has anybody posted the overall theory of the circuit? Isnt the mpsa13 kinda small to pump out a good signal? How to feed an 8hz into the filters.. where? Also.. R41 at 220R attenuates for phones right? I dont see the option for phones on sikverdog's board.

easier wave:
look the schematic , you know GND have 0 volt , battery 12volts , lm7808 +8volts and WRT +4 volts .frist check by multimeter , then if you have not same voltages check your tracks and parts like Resitors and wiring and ...
for example : for my detector have a very funny error , this error from two lm358 and they produce +6.5volts not +4 volts ,then when you are sure about all are correct next connect you coil and see your waves on oscope ( one prob on RX and on of them on TX)
TX : Vp-p 15.5 volts ,6.58kH
RX :should you adjust near 0 volt p-p . then put the prob on ne5534-6 and adjust it near 0 volts ( or under 200mv , you should have RX coil near 0Vp-p so be careful )
and about the headphone see schematic next you can add it to the board (in my country dont exist jack headphone,so any body know which part can i buy instead it )
my programer is ROTTEN so when i program pi16f88 i put my clip.
regards

[wlewis]

look the schematic ...

thanks.. very helpful. Does anybody have a schematic for an atmegaxx vli? Are pics are more stable than atmel chips? Separately regarding the coil would varnish work as a substitute for cyan glue post #1936? Am etching my pcb today.. i hope i got it right.

[mohandes]

thanks.. very helpful. Does anybody have a schematic for an atmegaxx vli? Are pics are more stable than atmel chips? Separately regarding the coil would varnish work as a substitute for cyan glue post #1936? Am etching my pcb today.. i hope i got it right.

you can do this by pic16f88 or 16f690 ( in this forum are ready)
good luck

[Tepco]

One Turkish VDI design, using Atmega8, rotational encoder and graphic display 128x64 is published somewhere on the forum, software included, search for it.

[mohandes]

if find it put it here for all
regards