IDX-PRO+VDI

[golfnut]

What is Coil L value or Dimater and turns


One side of the Tx coil should be connected to Battery -ve terminal

Dont make mistake of thinking PCB copper edge is battery -ve ( it sits 4volts above battery -ve terminal ) you cant use this copper edge for the tx return --- the tx coil return is the battery -Ve terminal

[ampirate]

I do not know Inductance other than calculated in previous posts.

But on TX, I used 35 turns of 0.7mm wire on a 27cm Diam Coil - for DD config, Cap=1uF, 30 ohms.

And RX is 260 turns of 0.2mm wire also 27cm Diam, Cap=33nF, 120 ohms.

[golfnut]

what is value of the two blue resistors standing up wired in series near Transistor ??

[ampirate]

what is value of the two blue resistors standing up wired in series near Transistor ??

They are a series of 2x of 20 or 21 ohm resistors. I did not have a 39 ohm.

[ampirate]

Board BUS = +4V

I replaced all the Transistors in case anything is burnt out :
Q1 : BC327
Q2 : BC547
Q3 : BC547
Q4 : MPSA13

Tested with Multimeter to Battery GND :

TX 1 = 0.0V
TX 2 = +0.02V

Q1 E = +8V
Q1 B = +8V
Q1 C = 0V

Q2 C = +8V
Q2 B = 0V
Q2 E = +2V

[akasyto]

They are a series of 2x of 20 or 21 ohm resistors. I did not have a 39 ohm.

You can try with 100 Ohm R7 resistor to get oscillator working after that you can reduce to 51 Ohm.

[ampirate]

I have a clear Sawtooth Oscillation of only 2V pp at about 300Hz across the TX coil - tested on Oscilliscope.

[mohandes]

I have a clear Sawtooth Oscillation of only 2V pp at about 300Hz across the TX coil - tested on Oscilliscope.

first you check without coil , see all +4v in all ICs with multimeter .if all thing right ( like value of res and caps and ......)
next you connect the coil . you should get in null less than 250mv ( pin6 ne5534 ) and.. ( see PDF file of make DD coil by Mr Dun make it )
and check part to part your PCB .
excuse for my English

[ampirate]

... see PDF file of make DD coil by Mr Dun make it

I already have made Coils ...
Can you give me a Link or Page to this PDF ?

[golfnut]

looks like issue with Q2

In order to conduct and work - the base should be more positive than the emitter

by at least 0.7v

you got

Q2 C = +8V
Q2 B = 0V
Q2 E = +2V


base should be more positve than the emitter

check r values here,
also with battery disonnedted what is resistance from q2 base to batt negaitve terminal.

should be ~4k one way or very high the other way

[mohandes]

I already have made Coils ...
Can you give me a Link or Page to this PDF ?

i upload for you
you can make TGSL coil too , i upload it too.DD coil is more easiest than CC coil it is my experiment.
regards
http://p30up.ir/images/x8rt6nk36brzlgn0lnt.rar

[Koala]

I do not know Inductance other than calculated in previous posts.

But on TX, I used 35 turns of 0.7mm wire on a 27cm Diam Coil - for DD config, Cap=1uF, 30 ohms.

And RX is 260 turns of 0.2mm wire also 27cm Diam, Cap=33nF, 120 ohms.

30 ohms does not sound right

[ampirate]

Sorry mistype,
TX = 1.4 ohms.

But on TX, I used 35 turns of 0.7mm wire on a 27cm Diam Coil - for DD config, Cap=1uF, 1.4 ohms.

And RX is 260 turns of 0.2mm wire also 27cm Diam, Cap=33nF, 120 ohms.

[ampirate]

Measuring Resistance across Q2 Base to BAT GND in both directions gives me: 160K and Infinity.
All Resistors test as connected properly: 1M, 1.8K, 2.7K to Q2 and V+,V+,V- respectively.

I replaced the Transistors just in case.
Are these the correct Transistors ? :
Q1= BC327
Q2 = BC547B (in place of BC237)

[ampirate]

Multimeter readings to BAT GND :
V+ = 8V
V- = 0V
1M Resistor to Q2 Base = 8V and 0.14V

Transistors Q1 and Q2 test as connected, and are installed as in Layout Q1 face right and Q2 face left.