Ivconic Fisher Gold Bug

[Andre]

[QUOTE = mmh; 286373] Ol?, andre.
R55, colocado no painel frontal, para controlar o modo de movimento
[ATTACH] 54652 [/ ATTACH] [/ QUOTE]
Hi mmh,

The R55, in the scheme, is a trimmer (trimpot). I believe it is adjusted only once.
Thank you for the image!

[mmh]

Hi,
An amendment to the comparator may be required. U4d,
Putting a diode on the output, u4d
In the event that he works all the way.
And u4d can be canceled until all stages are calibrated

[mmh]

Hi mmh,

It doesn't seem to be making much of a difference.

Hi andre.
R55, placed on the front panel, to control movement mode

[Andre]

R55,Adjust the offset of the op amp output voltage

(Translation difference)

Hi mmh,

It doesn't seem to be making much of a difference.

[mmh]

R55,Adjust the offset of the op amp output voltage

(Translation difference)

[mmh]

Hi, andre
R55, to adjust the output of the reference ampere shift, so that it corresponds to the next input, and does not increase it to saturation, or overwhelm the other stages

[Andre]

Hi,
Does anyone know what the function of R55 (100k trimmer)? It isn't working!
Thanks!

[Andre]

sinclairuser,
We are looking forward to obtaining the reliable schematic diagram for building a GB or GB2. Lars' scheme is doubtful, even though Ivconic did a good job on the Front-end.

Regards,

Andre

[sinclairuser]

[ATTACH]54622[/ATTACH]
I guess it's like a gold bug

naw it looks like a GB, but its another 12XX knock off inside, but there are credible clones of the GB2, bernte one was playing around with one a while ago
i'd ask him his opinion on the GB2, as an aside i tried to buy one and a T2 knock off but the stupid exporters put the stickers in the box, so customs seized them.
i asked them to leave off the stickers and decals so they would get through customs, they agreed then put the stickers in the shipment.
if you decide to buy one just be aware of this.

[Andre]

[ATTACH]54622[/ATTACH]
I guess it's like a gold bug

I think it isn't the same! However, we have to see the circuit.

[algan]

I guess it's like a gold bug

[Andre]

Dear mmh.
Thank you for your comments! I will do this in stages!
Regards,
Andre

[mmh]

Hi, ander
Yes .. the power supply is not critical if a suitable op-amp is used with the power supply.
My experience is modest and my words may be wrong.
I am an amateur and a little inexperienced,
This schematic is old and needs to be upgraded. Ivconic has put some ideas to develop it,
(Much thanks to the creditable Ivconic)
He pointed to weaknesses in the front end, power supply and reference amp which are no longer suitable after the development of his industry in terms of accuracy and low noise .....
If you are determined to build it, I advise you to make it in separate parts,
To adjust each phase separately, the coil parameters must be identical to the original, especially the phase difference between tx and rx, in order to be able to balance the phase capacitance at the two channels.
Maybe a better square wave for depth and stability,
And perhaps not in the event that the components on the schematic do not reject the harmonics and noise.

My circumstances are difficult. I write on mobile, and I am not good at English to communicate in this wonderful forum

[Andre]

Hi, mmh,
Your comments were very good! Power supplies with 78XX and LM317 regulator ICs with good capacitor filters are a good alternative for simplicity.
I think we can use the ICL8038 ic to generate the sine waveform for the transmitter circuit. Ivconics did a good job on the front-end circuit, as well as on the circuit design.

[mmh]

Hi
Greetings to all and the leaders of the forum
I suspect the component values you specified are correct.
They may also be designed to reinforce the difference between the two channels when metal is passed in front of the coil.
Only the outputs of the two channels must be balanced by the R15 R38. When there is no metal. So GEB operates at a value close to zero between the two channels.
Also the variable resistor at the front end outputs is important for setting the necessary signal amplitude.
I suspect the power supply regulators in the original schematic are better for less noise.
Also I suspect a better sine wave transmitter circuit for reducing harmonics.
Block devices need great attention in construction to block noise. If I could build it I would have made it in parts for modification and testing.

I say I think because I have no experience and practical experiences. And my humble experience in front of the senior of this wonderful forum
I wish you success. We benefit from your experiences in building the project.
It interests me.

I intend to build it when I have the testing equipment and components needed and the public electricity grid available.
Thank you
I write through google translate