Carl's fluxgate Gradiometer ckt.

[Krzysztof]

Hi Geo.
Not good. Only three active levels, something impossible.
Check the measurement.
You measure the PIN 14, 15, 2kom load to GND.
To be correct GND and Vcc.
Actuation of the serial number of a separate resistor compositions from Vcc to test PIN1-8.
No links with the SLC and the VCO, but the measurement DAC!
Try to do an experiment to change the levels of H / L for 1,3,4 PIN.
Is there something changes?
Is the rigid tension PIN3, 4, without any pins?
See why you need to wait 10 minutes, normally 1 sec after the configuration.
And you have a good frequency of the X-tal?
Because I can configure so long, because a small frequency.
Check out the case.
Best regards Chris.

[Geo]

Hi Geo.
Not good. Only three active levels, something impossible.
Check the measurement.
You measure the PIN 14, 15, 2kom load to GND.
To be correct GND and Vcc.
Actuation of the serial number of a separate resistor compositions from Vcc to test PIN1-8.
No links with the SLC and the VCO, but the measurement DAC!
Try to do an experiment to change the levels of H / L for 1,3,4 PIN.
Is there something changes?
Is the rigid tension PIN3, 4, without any pins?
See why you need to wait 10 minutes, normally 1 sec after the configuration.
And you have a good frequency of the X-tal?
Because I can configure so long, because a small frequency.
Check out the case.
Best regards Chris.

Hi Chris.
No, i don't check anything else for the time.
I will order new IC's and then i will put them on the pcb and i will make all the tests.
I will inform you.

Regards

[Geo]

VCO

Hi Chris.
I received the IC's, but i found the problem. Now i have another problem, this time with the VCO. I try the pcb without the SCL007. I connect the pin1..8 of the AD557 to +5V, and i short the R6. Pin 14-15 of DAC has 2.5V and the pin 16 has 3.2V.
I take good waveforms at Pin 2 and Pin 3 of the LM393 but no out at pin1. I measure DC voltage at pin1 and it is 0.1V. I attach the wave forms from pin3 and Pin2. At Pin 2 the voltage is 4V and at pin3 the triagle if from 3 to 4.8v. Transistors are OK, LM393 is OK (i replaced it 5 times with new)...., so Where is the Problem???
Any Idea!!!!

Regards

[Krzysztof]

Hi Geo.
All OK.
Never do on R6 short-circuit! R6min = 1Kom.
Q1 works as current source to loading C5.
Your Q1 is full replete now (open).
Tension on almost always larger Pin2 from Pin3 therefore Pin1 = 0.1 V.
Very small only time on open Q2 and you have unloading C5 opportunity to see on Pin1 small short spades(this will not alter tension practically).
In loudspeaker obviously nothing.
Arrangement works because on Pin3 = you have Pin5 saw which Q2 triagle.
When you give R6 = 2Kom, you will make him soft profile and you will see
small frequency.
Tensions will fall on PIN14 / 15, 16, tension will raise on Pin3.
Can give between Pin14/15 2Kom and GND additionally with aim of making the more logarithmic profile.
For safety check, or IC3 is warm.
Look for to GND short-circuit in neighbourhoods Pin1 maybe.
Loam have to GND resistance on Pin1, when switched off?
7Kom should be above, I think so.
Best regards Chris.

[Geo]

Hi Chris.
I tried with potentiometer 5K at R6. I had the biger wave at pin3 with R6 short. With R6=5K i have nothing at Pin3.
U3 is not hot. I measured pin1 with all components near it but i did not find any sort to anyone.
Tention of Pin2 is not more than Pin3. Pin2 is 4v and pin3 start from 3 and goes to 4.8. So there is some time from 4 to 4.8v where the tention at pin 1 must be "on". I afraid that the tentions are big, so the comparator is "on" at saturation. Who is your opinion??
When the inputs of the DAC are to 0 then the tention at pin16 is low and i have output at pin1 (low frequency).
I am very confused now

Regards

[Krzysztof]

Hi Geo.
First, make a good connection to the IC AD557_PIN3 a collector of Q1.
Check if R4 = R5 approximately 10Kom.
Check R8 = R9 around 10Kom.
Make sure R10 is set to 50%, does not shorted to GND on the line by R9.
Now a little test.
Set to R6 = 1.5 Kom.
Set to ADC_Pin6 = 5V, other inputs = 0V.
Level H Pin6_ADC a good signal from the Mag, the Pin14/15_ADC should be around 0,3 V.
On the Q1 emitter should be around 0,6 V.
At the base of Q1, Pin16_ADC should be around 1,3 V.
On Pin2_IC3 should be about 3,2 V.
On Pin3_IC3 should be fine saw(trogle).
The Pin1_IC3 should be a rectangle several hundred Hz.
VCO is a very clever and simple. It has a small range of control.
Too fast is saturated - so bad going at high gain settings.
To increase the sensitivity to small signals from the MAG, I proposed to add a parallel between Pin14/15_ADC 2Kom and GND.
Good luck.
Best regards Chris.

[Geo]

Hi Geo.
First, make a good connection to the IC AD557_PIN3 a collector of Q1.
Check if R4 = R5 approximately 10Kom.
OK
Check R8 = R9 around 10Kom.
OK
Make sure R10 is set to 50%, does not shorted to GND on the line by R9.
I have a fix 1K resistor and i check the vco with Oscilloscope
Now a little test.
Set to R6 = 1.5 Kom.
Set to ADC_Pin6 = 5V, other inputs = 0V.
Level H Pin6_ADC a good signal from the Mag, the Pin14/15_ADC should be around 0,3 V.
On the Q1 emitter should be around 0,6 V.
At the base of Q1, Pin16_ADC should be around 1,3 V.
On Pin2_IC3 should be about 3,2 V.
On Pin3_IC3 should be fine saw(trogle).
The Pin1_IC3 should be a rectangle several hundred Hz.
VCO is a very clever and simple. It has a small range of control.
Too fast is saturated - so bad going at high gain settings.
To increase the sensitivity to small signals from the MAG, I proposed to add a parallel between Pin14/15_ADC 2Kom and GND.
Good luck.
Best regards Chris.

Hi Chris.
I will make the tests on afternoom.
But the strange is other. I have at the inputs 2 and 3 of the comparator the exactly voltage references and waveforms as Carl says at his article. Why i have not signal at the output????? The case that i have exactly the voltages and waveforms as Carl says, means that all in the rear of the comparator work fine. I am afraid that at the limit the VCO don't work. I willl try it with Dac output at 1.3V or 0.7V.
I will write again later

Regards

[Krzysztof]

Hi Geo.

First, make a good connection to the IC AD557_PIN3 a collector of Q1.

Check the voltage on the IC legs, maybe somewhere out of touch?
Best regards Chris.

[Geo]

Hi Chris.
I found the problem but i am afraid that this VCO has big problem.
What is happening...
1. with R6=0 then with Dac out =0,01V i have about 60Hz.
2.with R6=0 then with Dac out =1.9V i have about 1800Hz
3.with R6=0 then with Dac out =2.5V No out.
If i will change the R5 (lower price) then i can do the Ic3a to give out with 2.5 v Dac out.
General if the voltage at pin_16 of DAC is bigger than 3.0v, then IC3a don't give signal at pin1.
4. With R6 =1K and DAC out =0.01V i have about 40Hz.
5. With R6=5K and DAC out =0.01V i have about 25Hz (not 5Hz who says Carl.)
6. With R6=5K and DAC out =1.9V i have not out at IC3a Pin1
In general worlds i see that this VCO is a 2 "speed" VCO. You can't make it with a fix resistance in the position of R6, to work from 5...10 Hz to about 2Khz. If i have the R6=5K so to have low frequency at small signal, then when i will receive a strong signal it will stop to Beep.
So i will try to change it. I want to connect a 4046 VCO. The main problem is that it begins to work with min signal in =1.4V about. We have at pin16 min voltage=0.8V and max =3V (with r6 near to 0V). So i need a simple circuit to add the 0.8v from pin 16 with a 0.6v from the power supply and to give me a 1.4v min.
Have you something ready???

Regards

[Krzysztof]

Hi Geo.
Good idea, realization not.
See patern internal Dac in # Post21. Manageable coupling has to be there to opamp.
Apply trick from steering the transistor amplifier of class the B.
Give 2 diode between Pin16_DAC in ranks (anode) and Pin14 / 15_DAC (cathode).
You have the demanded difference of tensions and required coupling!
Now exit Pin16_DAC has started for 1,4 V. The rest one should to You.
Problem in discussion from Damiafix was also VCO.
I came to this, that near correc start take-off and the configuration the SLC ( the of work perpendicular position, without movement during configuration) you receive on exit 0V.
Every the smallest anomaly of treasure has given since 0 the growth of signal in mountain now (obviously little, it depends from strength of anomaly).
This marks, that you need in borders 0 the most tender range you-0,3 V.
Near small signals will hear only clatters (0-20Hz).
This is digital instrument and exit has rectangle on loudspeaker.
This is not generator sinewave nor analog sinusoida; it for me this sounds cursedly.
I have tolerable digital sound 50Hz above ( I am already a bit deaf).
More then easily to choose initial the best range from possible ( logarithmic profile) and to reconcile from Carl.
Fact is irritating additionally, that bottom level (5%) it walks always there - nowhere is no homogeneous field, add to this operator's presence.
Best regards Chris.

[Geo]

Hi Geo.
Good idea, realization not.
See patern internal Dac in # Post21. Manageable coupling has to be there to opamp.
Apply trick from steering the transistor amplifier of class the B.
Give 2 diode between Pin16_DAC in ranks (anode) and Pin14 / 15_DAC (cathode).
You have the demanded difference of tensions and required coupling!
Now exit Pin16_DAC has started for 1,4 V. The rest one should to You.
Problem in discussion from Damiafix was also VCO.
I came to this, that near correc start take-off and the configuration the SLC ( the of work perpendicular position, without movement during configuration) you receive on exit 0V.
Every the smallest anomaly of treasure has given since 0 the growth of signal in mountain now (obviously little, it depends from strength of anomaly).
This marks, that you need in borders 0 the most tender range you-0,3 V.
Near small signals will hear only clatters (0-20Hz).
This is digital instrument and exit has rectangle on loudspeaker.
This is not generator sinewave nor analog sinusoida; it for me this sounds cursedly.
I have tolerable digital sound 50Hz above ( I am already a bit deaf).
More then easily to choose initial the best range from possible ( logarithmic profile) and to reconcile from Carl.
Fact is irritating additionally, that bottom level (5%) it walks always there - nowhere is no homogeneous field, add to this operator's presence.
Best regards Chris.

Hi Chris.
I will try it today and i will inform you

Regards

[Geo]

Hi Chris.
I will try it today and i will inform you

Regards

Hi Chris.
I tried it without results. When the tension at pin 14=0.01 ...1.2 then the voltage at pin16 is 0.6v bigger. If the voltage at pin14 is 1.1v or bigger then the voltage at pin16 is 1.2v bigger. I have the lm393 out of the socket, R6 and R4 are unconnected. I did not unconnect the Q1 and Q2 (is there any problem?).
Any idea??

Regards

[Krzysztof]

Hi Geo.
I see two roads.
1_ Pin16 addition 10Kom resistor to Vcc.
May be problems with the smallest values of tension.
2_ To get the voltage from 1.4 V to your other VCO:
Rather than give the R6 -> 2 diodes in series as above.
Leavin Q1.
Leavin R4 and R5.
1Kom collector of Q1 to Vcc.
Of course, C5, Q2, IC3 disconnected.
Then the emitter voltage of Q1 you have requested.
Best regards Chris.

[Geo]

Hi Geo.
I see two roads.
1_ Pin16 addition 10Kom resistor to Vcc.
May be problems with the smallest values of tension.
2_ To get the voltage from 1.4 V to your other VCO:
Rather than give the R6 -> 2 diodes in series as above.
Leavin Q1.
Leavin R4 and R5.
1Kom collector of Q1 to Vcc.
Of course, C5, Q2, IC3 disconnected.
Then the emitter voltage of Q1 you have requested.
Best regards Chris.

Hi Chris.
With "Rather than give the R6 -> 2 diodes in series as above" do you mean to replace the R6 with 2 diodes in series??

Regards

[Krzysztof]

Hi Geo.
Yes!
But the output voltage from the emitter Q1!
Chris.