IDX-PRO+VDI

[dekoratör]

You have remove U7(LM393) andQ3 (BC327-547)of theIDX-PROPCBand thenconnections are madeaccording to thePCB2tones.Regards.

hi eduardo 1979.
idxpro and 2 tone board, I did it.
works nicely, but the sound of iron thin
coin thick voice
Can you help me please
hand-made using the coil
1uF 35 turn 270 turn 33nf
c 24 I changed 1NF because with 100pf disc not work

best regards

[Schatztaucher]

hello all,
have something on my pcb soldering. the last test is probably something to do with Q3, Q4 happens ... I replaced the parts and my idx beeps again. However, it has become very quiet. First I had a BC547A it. But now a BC547B. this is the reason because of the volume?
the tx-frequency is now almost ok. 6.47 kHz. I still have to fine tune. but the rx-frequency is not there.
1: I have a switch
2: after a short time, gives a beeping from the elktronik
3: vdi indicates something
4 ton can be influenced by gb and treshhold
5: if you move something through the coil, nothing changes

Then I pressed pinpoint. the clay was still soft. now you can hear it any more. have the idx off and on again. The tone is now very, very quiet. is probably a little burned out again :-(

I have installed:

U1-OP177
U2 CD4066
U3 LMC6484
U4, U7, U8-LM393
U5, U6-LM358

Q1 BC327
Q2, Q3-BC547B
Q4-MPSA13

in the circuit where I have to search for the error to find missing with the rx-frequency?

would be very nice if someone could help me, I do not know what to do. maybe I should throw the board into garbage. and order me a circuit board of silverdog.


http://www.youtube.com/watch?v=F1YKW...eature=mh_lolz

[smity]

First, the receiver coil escape. Secondly shorten all the wires from the controls. And then, if they do a little bit longer, you can listen to the radio in the device. Otherwise, the check standard (voltage, current ...)

[Schatztaucher]

thank you smity
Of course I want to test the current and voltage. But no one can make accurate disclosures, which voltages on certain points, I must have in the circuit. ok, I'm testing on .....

[Schatztaucher]

I just decided to order my kit from the silverdog and to compare it with my motherboard. Besides, I'm going to buy me an original coil. can someone tell me which coil is ok? I found three.

[dfbowers]

See post # 535.

http://www.geotech1.com/forums/showt...=18051&page=22

[Schatztaucher]

can anyone tell me how many cm between the ears? so I know whether my rods fit

regards

[Schatztaucher]

thanks don

[dekoratör]

2 tone problem

my idxpro with 2 tone bord working nice but volume is reverse.

iron nice thin sound and money bad thick sound.
What should I do? some body help me?
i made this circuit:

[cnckecgo]

eduardo 2 tone problem please

[eduardo1979]

eduardo 2 tone problem please

I can not guess your problem in the 2 tones. You put a video on the forum and so we doubt. My detector works perfectly with the two tones. I'll leave here a video of my detector with 2 tones. Regards.
http://www.youtube.com/watch?v=lyg_D...75AUAAAAAAAAAA

[mikebg]

Bad TX circuit

Revision of TX used in Classic family

This posting is a continuation of my posting # 597.
Objective of the revision is to analyze, experiment and redesign TX circuit.
A TX for metal detectors must meet the following requirements:
1. Work equally well with different by diameter TX coils.
2. Work with enough high power (Ampere-turns) at given supply voltage.
3. Work with maximal efficiency at limited mass of wire used in the TX coil.
Maximal power and efficiency can be achieved: (a) by reducing the resistance of the TX coil (for example coil r = 1,5
Ohm as shown below), (b) by using large tank capacitance formed with MKP type capacitors (for example tank C = 1uF
as shown below) and (c) by quick operating automatic control maintaining stabile amplitude of oscillation near to
saturation of pumping transistor (Q1 below, but thre is no control :-(.
4. Do not get amplitude and angle modulation when operator changes distance of the TX loop to the ground or when
the loop passes over ground with different properties.
The modulation of TX by the ground is very harmful for operation of metal detectors because the AIR signal appears
as an additional GND signal which differs in phase from the true GND signal, but is parasite modulated in the same way.
The problem is even more complicated because the true GND signal is generated by a modulated by ground
transmitter.

What block diagram should have TX for metal detectors?

The most suitable block diagram of TX which can suppress amplitude and angle modulation was shown in the forum.
In theory, the resistance of environment is the true load for TX end stage. In practice, the most part of tank energy dissipates in resistance of TX coil, which forms a LC "tank circuit" or "tuned circuit". In German is used term "Schwingkreis", in Russian - "колебательный контур".
To suppress angle modulation, the tank circuit is not part of regenerative oscillating loop.
To suppress amplitude modulation, a P-I-D controller uses signal from an ampllitude detector connected to TX tank
circuit. The end stage of TX pumps the LC tank circuit with current pulses having less than 25% duty cycle. The quick operating P-I-D controller increases width of pumping pulses when the search coil decreases height (or passes over more absorbing ground).

HOW TX OF CLASSIC FAMILY WORKS?
The answer is: very bad.
Transistor Q1 operates as an amplifier class C. Instead P-I-D (proportional-integral-derivative) controller is used proportional controller (amplifier) with Q2.
Transistor Q2 also should operate as an amplitude detector, but it can not make this because the circuit is incompetent designed. It should maintain stabile amplitude of oscillation as a self-biasing oscillator. The controller can not operate because transistor Q1 pumps the LC tank circuit with current pulses having 50%
duty cycle as shown below. This makes maximal possible power and the controller can not increase it more.
Incompetent designed is not only the block diagram (P-controller instead P-I-D controller) .Bad designed are the amplitude detector, which can not detect amplitude (see the voltmeter below) and not suitable starting operating points
(showed below with blue numbers). In addition to this:
(a) resistor R7 decreases TX power and efficiency,
(b) resistor R10 eliminates operation of amplitude detector, eliminates self-biasing action, decreases amplification of the P-controller, and
(c) a large capacitance C21 charges and discharges slowly.
At the end of this list of drawbacks, the emitter junction of Q2 (used as amplitude detector) has properties as a Zener diode.
http://www.geotech1.com/forums/showp...2&postcount=39
However there is no breakdown of emitter junction in this design because the amplitude of oscillation is too small - almost 4.3V at
possible 8V. However that means low utilization of supply voltage which is 4.3 : 8 = 0.5375 or only 54%.
The SPICE can not simulate the Zener action of emitter junction because SPICE model of transistor Q2 contains no information for emitter breakdown voltage. I measured about 11V Zener voltage for most widely used transistors. If the amplitude detector where designed correctly, the average voltage showed by voltmeter below should be negative. The positive voltage shows that amplitude detector can not operate and TX circuit can not suppress the amplitude modulation when TX coil moves.
Please simulate the circuit with different SPICE programs. My program CircuitMaker shows that the current in tank circuit has
amplitude 174 mA. That means RMS value 123 mA and the TX power is too small - almost 23 mW.

CONCLUSION
Below is shown an incompetent designed circuit diagram of TX, which is not suitable for sensitive metal detectors.

What follows?
In the next my post will be described how a competent design can improve operation of this circuit. We will obtain suppression of AM and triple more power.

[eduardo1979]

Revision of TX used in Classic family

This posting is a continuation of my posting # 597.
Objective of the revision is to analyze, experiment and redesign TX circuit.
A TX for metal detectors must meet the following requirements:
1. Work equally well with different by diameter TX coils.
2. Work with enough high power (Ampere-turns) at given supply voltage.
3. Work with maximal efficiency at limited mass of wire used in the TX coil.
Maximal power and efficiency can be achieved: (a) by reducing the resistance of the TX coil (for example coil r = 1,5
Ohm as shown below), (b) by using large tank capacitance formed with MKP type capacitors (for example tank C = 1uF
as shown below) and (c) by quick operating automatic control maintaining stabile amplitude of oscillation near to
saturation of pumping transistor (Q1 below, but thre is no control :-(.
4. Do not get amplitude and angle modulation when operator changes distance of the TX loop to the ground or when
the loop passes over ground with different properties.
The modulation of TX by the ground is very harmful for operation of metal detectors because the AIR signal appears
as an additional GND signal which differs in phase from the true GND signal, but is parasite modulated in the same way.
The problem is even more complicated because the true GND signal is generated by a modulated by ground
transmitter.

What block diagram should have TX for metal detectors?

The most suitable block diagram of TX which can suppress amplitude and angle modulation was shown in the forum.
In theory, the resistance of environment is the true load for TX end stage. In practice, the most part of tank energy dissipates in resistance of TX coil, which forms a LC "tank circuit" or "tuned circuit". In German is used term "Schwingkreis", in Russian - "колебательный контур".
To suppress angle modulation, the tank circuit is not part of regenerative oscillating loop.
To suppress amplitude modulation, a P-I-D controller uses signal from an ampllitude detector connected to TX tank
circuit. The end stage of TX pumps the LC tank circuit with current pulses having less than 25% duty cycle. The quick operating P-I-D controller increases width of pumping pulses when the search coil decreases height (or passes over more absorbing ground).

HOW TX OF CLASSIC FAMILY WORKS?
The answer is: very bad.
Transistor Q1 operates as an amplifier class C. Instead P-I-D (proportional-integral-derivative) controller is used proportional controller (amplifier) with Q2.
Transistor Q2 also should operate as an amplitude detector, but it can not make this because the circuit is incompetent designed. It should maintain stabile amplitude of oscillation as a self-biasing oscillator. The controller can not operate because transistor Q1 pumps the LC tank circuit with current pulses having 50%
duty cycle as shown below. This makes maximal possible power and the controller can not increase it more.
Incompetent designed is not only the block diagram (P-controller instead P-I-D controller) .Bad designed are the amplitude detector, which can not detect amplitude (see the voltmeter below) and not suitable starting operating points
(showed below with blue numbers). In addition to this:
(a) resistor R7 decreases TX power and efficiency,
(b) resistor R10 eliminates operation of amplitude detector, eliminates self-biasing action, decreases amplification of the P-controller, and
(c) a large capacitance C21 charges and discharges slowly.
At the end of this list of drawbacks, the emitter junction of Q2 (used as amplitude detector) has properties as a Zener diode.
http://www.geotech1.com/forums/showp...2&postcount=39
However there is no breakdown of emitter junction in this design because the amplitude of oscillation is too small - almost 4.3V at
possible 8V. However that means low utilization of supply voltage which is 4.3 : 8 = 0.5375 or only 54%.
The SPICE can not simulate the Zener action of emitter junction because SPICE model of transistor Q2 contains no information for emitter breakdown voltage. I measured about 11V Zener voltage for most widely used transistors. If the amplitude detector where designed correctly, the average voltage showed by voltmeter below should be negative. The positive voltage shows that amplitude detector can not operate and TX circuit can not suppress the amplitude modulation when TX coil moves.
Please simulate the circuit with different SPICE programs. My program CircuitMaker shows that the current in tank circuit has
amplitude 174 mA. That means RMS value 123 mA and the TX power is too small - almost 23 mW.

CONCLUSION
Below is shown an incompetent designed circuit diagram of TX, which is not suitable for sensitive metal detectors.

What follows?
In the next my post will be described how a competent design can improve operation of this circuit. We will obtain suppression of AM and triple more power.

Mikebg Thanks for your comments. You are a machine! Best regards!

[mikebg]

Mikebg Thanks for your comments. You are a machine! Best regards!

NOT!
I have time only for one or two posts per week.
I was a radio amateur, which hobby was to design TXs, RXs and antennas for QRP amateur radio.
QRP means "Decrease TX power". Now I try to increase TX power in IDX and other metal detectors, which is absolurely stupid according the QRP principle.
However most participants in this forum think that more TX power means more depth of detecting. Let they experiment the more poweful TX circuits to see what happens with AIR&GND signal

[juice2839]

IDX Depth

I have finished building Silverdogs IDX pro kit. I have also wound a homemade coil per the specs I found in this thread. I am getting about 6 inches on a US Quarter and about 5 inches on US penny, nickel, dime. Does this sound about right for a homemade coil? Or is it really lacking in depth? These depths were in air with no discrimination. If I put it in PP mode I can detect deeper by listening to the tone increase/change. Also the Disc seems to come on very quick with the pot. IE 1/4 turn and I loose nickels foil and alot of depth on pennies and quarters (maybe detects them at 2-3 inches). Thanks for any replies.