transmiter 11kh

[mikebg]

TX for Messina

TX for Messina

The idea is TX to be powered without voltage stabilizer for maximal efficiency. The oscillation amplitude is
stabilized by P-I controller. For its reference voltage is used a LED. Thus, the amplitude of TX
oscillation decreases with depletion of the battery, but this change is slow, so no impact.
Problem for a powerful TX is the battery voltage and its weight. The idea is to use 2 laptop battery packs for power supply
and to use the laptop for battery charging.
For simmetry, the TX coil consists of 4 equal sections, 0,3 ohm each. So the maximum of pumping
current pulse is Im=21/0,3=70A. For observation of current pulse is used resistor R9 made of
brassleaf. This allows to adjust voltage divider R5-R6 for maximal undistorted amplitude.
The SPICE shows that circuit can work well with only one NMOS.
The circuit diagram is an idea only.

[Esteban]

Dimmension of box:

[Esteban]

Before some editions (convert in gray scale by Irfanview program, "clean" the page of notebook, etc.), here the schematic. This use SCR TIC 106 and unijunction transistor. Change capacitor 350 nF, change frequency.

The TX coil is: 74 turns + 2 turns - 27 x 20 cm - wire 0,35 mm

The RX coil is: 74 turns - 27 X 20 cm - wire 0,25 mm

Experimenting the 0.005 cap. in Tx coil changes Q of the coil.

Maybe this need a transistorized preamp. for better performances (better sensibility). Buzzer instead speaker is used. This is a crude schematic.

[Esteban]

Hy Mesy

I'll post simple 2 box, think TX is powerfull. I'll search in my "enormeous" archives.

[mikebg]

Award "Carbon paper"

Award "Carbon paper" for bad copying in TX design

The (R)EMI group established a prize "Carbon paper" for designer copying circuit diagram without thinking how it must operate.
Already submitted nominations for Section TX.

One nomination of Mikhail Vulkov (mikebg) for circuit diagram TX200809-1. He copied design data for TX coil and P-I controller from Garrett designs, free to think what parameters they should have. The (R)EMI group found many shortcomings of the circuit diagram, which was published.

The other nomination is designer Mark Rowan. Copying a circuit diagram of TX, he introduces a switch LOW POWER free to think for parasitic modulation. Measurement of the attached circuit diagram shows that at LOW POWER mode, occurs at high parasitic amplitude modulation of all known other circuits, because the TX tank is pumped with equal current portions. When sensor get nearer to conductive ground, the amplitude of TX magnetic field decreases significantly. Adjustment for low parasitic modulation for TX of Coinmaster, TM808 and Eagle, will be published in the section "Modifications".

[mikebg]

Absorbing modulator for TX coil

Absorbing modulator for TX coil

This is a tester for measurement of parasitic TX modulation of TX field. It mimics the process when changes height TX coil or conductivity of ground changes. The NMOS acts as a switch involving inductively a loop with timeconstant L / r.

To mimic the effects of salty beach, a low ohm trimmer is used. The diameter of wire for loop is not important. The loop should be placed near to TX coil.

[mikebg]

TX with NMOS transistor

TX with NMOS transistor

The NMOS can increase efficiency and TX power (ampere-turns) only if is connected to tap of TX coil.
R10 is used to damp VHF oscillations.
D3 shortens discharge of input cpacitance of NMOS.

[mikebg]

Modification 2 of TX200809

Modification 2 of TX200809

List of modifications:
1. Resistance of TX coil is reduced to 1R4.
2. Center tap in TX coil for antenna match.
3. Tank capacitance is increased to 1uF.
4. Two tank capacitors for frequency adjustment.
5. Reduced resistance of R11 to 4R7.
6. Components for supply of preamp from TX coil.

Description of mods:
Mods 1, 2 and 3 increases power (ampere-turns) of TX field.
Mod 5 reduces pulse width (duty cycle of current pump).
Mod 6 is made in pcb of preamp. The rail supplying with +5V the TX section appears COM rail for preamp. Voltages +Vcc and -Vee are stabilized by P-I controller.

Adjustment:
- Connect scope across R11.
- Shunt R8 with P1 - a potentiometer 1M.
- Adjust clock frequency with R2 for shortest pulse of current pump.
- Adjust P1 untill appears depression in current pulse.
- Adjust clock frequency for center position of depression.
- Adjust P1 untill depression disappears.
- Measure the equivalent value for R8.

[mesy64]

Hi all
I built a wire coil with 0.40 score for tx
But with more coils of the detection range was
please me for disclosing more depth to help
Thanks!
mesyna

[BigBang]

Dear Friend

I gave the numbers are just examples . Your output current is good enought to go deeper with Tx coil. I advice you to read Mike BG's explanation again . Brief informations are important in there . This subject consists many calculations .

Yours Sincerely ...

[mesy64]

Dear friend

You did not write Tx inductance but it must be 6,34 mH. for 11 Khz. frequency. I think Tx coil has too high resistance It can be 4-5 ohm or more low .You can ,

Increase value of resonant capacitor (i.e. 100 nF) and degrease the induction . If you'll use 100 nF induction will 2,09 mH. In this case , you'll reduce turn number of Tx coil. And you can use 0.35 , 0.40 or 0.50 mm diameter copper wire to reduce the resistance

By the way , I asked output current for Tx moment . Just wondered

Thank you friend's


I only need to change tx??? Rx does not change?

What to tx I turn away?

Store the name that I took part rx Esteban told me to change it, and show sensitivity to change, and the letter he was absolutely correct.

Friend's changing the transmiter Profile tx power increases and the depth of search and disclosure will be more?

With respect
mesyna

[BigBang]

Hello Friend's

33 nano farad capacitor value that I value it too low and I and its sensitivity to Tghyyrmy.

Current output is about 45 milli volts

tx 33 ohm is

Please help me

With respect

mesyn

Dear friend

You did not write Tx inductance but it must be 6,34 mH. for 11 Khz. frequency. I think Tx coil has too high resistance It can be 4-5 ohm or more low .You can ,

Increase value of resonant capacitor (i.e. 100 nF) and degrease the induction . If you'll use 100 nF induction will 2,09 mH. In this case , you'll reduce turn number of Tx coil. And you can use 0.35 , 0.40 or 0.50 mm diameter copper wire to reduce the resistance

By the way , I asked output current for Tx moment . Just wondered

[mesy64]

I'm sorry but I think my sentence is basic and clear enough.By the way , my original language is not English. Can you give us value of the resonant capacitor(s) , inductance , output current ( not a must ) and resistance of transmitter coil ? It may help us to understand the problem .

Hello Friend's

33 nano farad capacitor value that I value it too low and I and its sensitivity to Tghyyrmy.

Current output is about 45 milli volts

tx 33 ohm is

Please help me

With respect

mesyn

[BigBang]

Hello Friend's


I did not understand your question

If you ask a little more clear

With respect

mesyna

I'm sorry but I think my sentence is basic and clear enough.By the way , my original language is not English. Can you give us value of the resonant capacitor(s) , inductance , output current ( not a must ) and resistance of transmitter coil ? It may help us to understand the problem .

[mesy64]

Dear Mesyna , if you have correct capacitance an inductance values with original circuit , could be a big mistake . Mike BG wrote very critical clues about antennas. Did you reduce tx coil resistance ?

Hello Friend's


I did not understand your question

If you ask a little more clear

With respect

mesyna