lobo improved

[porkluvr]

It seem that 20 khz signal is modulate at 10 khz.
Tested oscope, it's ok.
Thinking that problem coming from 7660, that work at 10 khz half F generate from 7555, i remove it but nothing change!
Next step is: remove 4024 and woodo rite!!!
first photo is on 7555's pin 3, second on pin 7.

Bye max

Recalling my days when I used to push an oscilloscope probe for a living (back when I had a job); that looks to me like you may have a short circuit between two signals. Measure ohms between 4024-1 and 4024-12. Should be megohms resistance between. A kilohms reading may indicate a bad 4024. A low ohms reading could be a solder bridge.

Before you remove anything else, poke around with your scope probe until you see another point on your PCB that exhibits the same waveform. If you find it, that will be a clue!

[maxbiri]

Hi All

It was 4024!

I check again all, no error, shortcircuit and pcb was washed for removing fluxant.
I cut trace from pin 3 of 7555 and pin 1 4024 and magicaly i have good square wave form and stable F on pin7.
I desoldered 4024, it was the only ic directly soldered on pcb!, i forget first Murphy's law , put a socket and change 4024 with one from ST, now all seem OK.
Now i can restart test.

Bye Max

[maxbiri]

Hi Porkluvr

I check Foma's schematic and see yours corrections.
I think that tx tank capacitor must be 47 nf and not 4.7 nf, Foma use 1.33mH tx and not 10 mH!
I presume that my first idea using 10 mH as RX and not Tx is correct.
Solved the problem around 4024 now citcuit is more stable and i gain 2 cm in deep but again i think that 20-22 cm in air is not a good result for a 50 €cent.
I test even a omega coil style coil, Magnum type, and after mach tank capacitors it work, more or less,in the same way as DD.
If you need same photo about signal in lobo let me know and i will do.

Bye Max

[tchoci]

LOBO the best. 50 €cent -32sm. for air.Discriminate-OK,F=17kHz,Vpp/gen.-14v.Ground-OK
Q1-2T914A;U1-HA17555;U4,U7-NE5532;U10,U11-OP177;Ctx-44nf;Crx-1,3nf;U8,U9,U14-LM158;U13-TL072

[FOMA]

HI TCHOCI.

The Good results.
What amount whorl TX and RX?
What sizes of the sensor?
If possible photo.

[tchoci]

Hi,FOMA
coil-Tx=65/0,28 Rx=170/0,22 D=22sm.

[tchoci]

Hi,

[porkluvr]

LOBO the best. 50 €cent -32sm. for air.Discriminate-OK,F=17kHz,Vpp/gen.-14v.Ground-OK
Q1-2T914A;U1-HA17555;U4,U7-NE5532;U10,U11-OP177;Ctx-44nf;Crx-1,3nf;U8,U9,U14-LM158;U13-TL072

Congratulations tchoci! Sounds like you have a winner. From your data it is easy to approximately calculate your transmit coil's inductance by using resonance formula, but your receive coil will remain unknown because that is not a tuned circuit. Do you have means to measure RX coil inductance? Please tell if you can.

Hi,FOMA
coil-Tx=65/0,28 Rx=170/0,22 D=22sm.

Update: You have posted your coil dimensions and winding numbers so I think I could use a coil calculator to determine RX coil inductance.

Why is there only one number for coil dimension? If this is a DD coil we actually need LxW for more complete detail. Or maybe it is OO coil? What coil configuration did you make?

22sm (or 22cm?) is about 8.66 inches... I'll figure this out... gotta' go now, bye.

Wait, one more question: Should I assume the 0,28 and 0,22 wire width numbers refer to bare wire? (Of course, stupid question. Right?)

[FOMA]

HI THCOCI.
How much mA it is necessary for scheme
What microcircuit U6?
Strange that capacitor Crx = 1,3 nF, he must capacity =* 8 nF.

[tchoci]

Hi Foma,
The coil is DD ,
Crx-1,3nf the best GROUND in real conditions
8nF don't have good GROUND
i tested this on the field

[tchoci]

maximum resonance of Rx is given by 3,3 nf but no land.

A perfect sine of Tx is obtained by 2t914a and Ctx 44nf, total consumption of the appliance without sound is 71mA

[tchoci]

thank you for the scheme and developed platka.Imashe error SW1A just have to pass the lower conclusion above does not work correctly because of the general regime.

[FOMA]

HI TCHOCI

Last question - what microcircuit U6?

[tchoci]

U6-lm392

[tchoci]

Hi FOMA,
I have several adjustments that you forgot to write; R7-1.25kom; R49-200kom; R51-100kom; R53-82kom