I need help

[WM6]

Sounds like a good plan.

Maybe you all are wrong. As you can see here yhl is an experienced detector builder:

http://www.geotech1.com/forums/showp...01&postcount=6

[Carl-NC]

I agree, HH would be too difficult. What about the GoldPic?

[Qiaozhi]

yup. I am prepared. I can make their home work in stead them. they send PCB to me, I fix it and send back. for some money they get working one back.

Sounds like a good plan.

[kt315]

For you and me ... I agree. But for yhl ... I think not.
Unless you are prepared to provide technical support with the HH building.

yup. I am prepared. I can make their home work in stead them. they send PCB to me, I fix it and send back. for some money they get working one back.

[Qiaozhi]

I suggest him to buy fabric made PCB from anyone. if he will solder properly all components at the PCB he will get working legendary HH without even using o-scope! what may be better good project than HH for some one?!

For you and me ... I agree. But for yhl ... I think not.
Unless you are prepared to provide technical support with the HH building.

[kt315]

The Hammerhead PI is too complicated for a beginner. With the different options available in the project, and the difficulty of understanding English, this would not make a good project for yhl.
I would suggest starting with the Sandbanks PI -> http://www.geotech1.com/cgi-bin/page...anks/index.dat

I suggest him to buy fabric made PCB from anyone. if he will solder properly all components at the PCB he will get working legendary HH without even using o-scope! what may be better good project than HH for some one?!

[Qiaozhi]

The Hammerhead PI is too complicated for a beginner. With the different options available in the project, and the difficulty of understanding English, this would not make a good project for yhl.
I would suggest starting with the Sandbanks PI -> http://www.geotech1.com/cgi-bin/page...anks/index.dat

[kt315]

Please give me a simple and practical PI circuit

do Hammerhead PI, this is particularly described and practical circuit.

especialy for you now.

[technos]

You all talk - no listen!

yhl needs the benefit of doubt on this. I think there is a language barrier for him in that he can get his Chinese glyphs into English (using online language tools), but really does not know how to get English into Chinese.

[Fred]

Friends. You can help me to establish a stable ETI561, I need your help to improve circuit

Technos has given you excellent advices,a least you could listen to him.

[yhl]

Please give me a simple and practical PI circuit

Please give me a simple and practical PI circuit

[pebe]

You all talk - no listen!

[yhl]

Friends. You can help me to establish a stable ETI561, I need your help to improve circuit

[technos]

To avoid drift you need to use polystyrene capacitors in the Q1 oscillator circuit instead of ceramic capacitors. This is what it means when it says "styro" for caps C2/C3. An admission that this circuit can drift.

I would also add a voltage regulator to the circuit, and switch Q1 to a uhf transitor (less internal capacitance). I would use metal film resistors for R2, R5, R8, R9. After you have done all that, the circuit is going to be as stable as you are going to be able to make it.

It also helps to keep all component leads short as possible.

The techniques to make an oscillator stable is the same that you would use in radio circuits.

Good luck YHL. You are working hard!

[yhl]

Do you have a better circuit it?
I ETI561 is well /
I want to build CCO's look.
I like to play production