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Offline Gramps43
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« Reply #190 on: July 05, 2010, 05:10:52 pm »
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Xavier:

Got a question or two for ya concerning coils.  First do you shield your coils, if using flat wound how?  Second if you shield where do you connect the shield?  Nothing I've seen so far has addressed this

Mucho thanks,
Dennis

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Offline Eugene52
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« Reply #191 on: July 05, 2010, 06:09:44 pm »
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Quote:Posted by Gramps43
Xavier:

Got a question or two for ya concerning coils.  First do you shield your coils, if using flat wound how?  Second if you shield where do you connect the shield?  Nothing I've seen so far has addressed this

Mucho thanks,
Dennis


Hello Dennis . Have you seen this article ? Here is an Excellent tutorial on PI coil winding and it does mention shielding techniques . Written by "other forum" PI expert bbSailor . A must have for any PI coil
builder !! So far the PI flat coils I have seen are designed and precision wound in a manner to where shielding is not required . If shielding is required on a flat coil you may look into RFI shielding
"spray enamel' such as nickel . see photo too:


HH..........Eugene

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« Reply #192 on: July 05, 2010, 07:58:52 pm »
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Thanks for the come back Gene, yup I saw bb's tutorial and saved it.  The question I have is where the shield should be connected in the DBP 2010 circuit?  I haven't seen that covered or my aging eyeballs missed it.

Dennis

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« Reply #193 on: July 06, 2010, 05:29:14 am »
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Can someone please explain this to me, I maybe missing something:
That a quick look on page 1 of this topic at the bottom thire is a picture of a board now look at T1 it looks to be an EBC transistor T3 and T4 are the same type, on T3 the flat part needs to be facing the small board. How can T4 the same type straight down from T3 work? The way its installed the emitter is in the wrong circuit...and T6 would be wrong too.net


I'm having problems with mine and started looking over all the boards and now I'm lost...


Darkkitten did you have problems with the fuse?
I see on your board what looks like a wire soldiered to the top jumping over the fuse



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« Reply #194 on: July 06, 2010, 12:43:33 pm »
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Well here we go the confusion has started now did I not say this would happen? OK Vdubber what are the transistors that you are using? and by the way the schematic shows PNP and they really are NPN on the piggy back board.

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« Reply #195 on: July 06, 2010, 01:21:11 pm »
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hi,
yes, charging an empty 4700uF capacitor (first time run) will draw a bit more than 500mA, using slow fuse or 800mA fuse will cure this problem. The power transistor can handle up to 10A, so this shouldn't really pose a problem.
I have written about everything concerning transistors, and PCB (original one since there is a confusion with many PCBs) so just scrool back and read.
Perhaps a bit of advice for builders; do not alter the value(s) or tolerances of elemnts unless one is positive about what he/she is doing and want to achieve. Good soldering is a must, one is dealing with high frequencies and high amplifications, washing off the flux with an appropriate solvent (such as IPA alias 2-propanole) is an imperative, as well as applying protective coating on finished PCB befor applying voltage to the circuit. Building an PI is not a begginer's project.

Good luck,
d.

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« Reply #196 on: July 06, 2010, 05:10:32 pm »
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Well Im using NPN (2n4124) for the small board and T1 and T2 on the large board (EBC)
T3 T4 (2n4126) and T6 (2n4403) are PNP and the datasheet shows them EBC also... so when I look at the picture did they use one EBC and ond CBE?

My soldier is fine and have washed the board twice even using an old toothbrush

This is not my first project but I habe never had this many problems

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« Reply #197 on: July 07, 2010, 01:32:13 am »
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If you are using 2n4124 you will see that T3 on the component lay out of the piggy back board is the wrong way round you will have to use the schematics to make sure that you have them in the right way round take the component lay out and look at the schematics you will see that on the schematics Emitter of T3 is going to R44 now if you look at the component lay out you will see that Emitter is going to R48 you will just have to take the time to do this any how like you said that you are familiar with these kind of projects it should not pause any problem for you to check the direction of the components.

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« Reply #198 on: July 07, 2010, 09:25:10 am »
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Hi,

Here are some ?flight instructions? based on frequent questions?..

 

The PNP transistor symbols are used all over in module schematics (small PCB) where NPN should be. This is just a typo; just connect the Emitter, Base and Collector as shown DO NOT turn the transistors polarity.

 I have replaced 2N4124s with BC546s, the 2N4126s with BC556s, 2N4403 with BC327 and obsolete N/A LF357 with TLE 2071 (IC has the same pining so no extra rearrangements are required). The uA709 is a 709 OPAMP, also marked as LM709.

In the PCB ?artwork? I have replaced all the original US transistors pinning (EBC from bottom) with   European (CBE) ones, but the Darlington MPS A14 (I have used original Fairchild?s) and the corner transistor marked T1 on the small (module) PCB. You will have to band the Base pin for that one to solder it in. I have slightly misplaced some resistors in PCB, use schematics and pictures to help yourself.

There are two capacitors marked 12nF which is not a standard value, and you will probably not be able to get them. I have used 10nF and 2nF in parallel instead; there are extra spaces (and holes) on PCB for that. There are some capacitors marked ?MKT? which is a polyester type, I have used multilayer instead. I have used ceramic, electrolyte and tantal-electrolyte capacitors where shown (in schematics) and multilayer type everywhere else.

All the resistors should be of 1% tolerance, I could not get all the exact values for about 5 resistors, so I used at maximum 2% off the nearest value.

Please note, the headphones output is designed for high impedance earphones, use loudspeaker?s output for common 8-20 ohm ?walkman? earphones.
 

Have fun,

d.


P.S. If it still doesn't work, one can always be ordered from me Cool

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« Reply #199 on: July 08, 2010, 08:35:36 am »
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please talk about dbp2010 depth search
can i find a 30*30 metal in 2.5 m
thanks

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