BARACUDA-Legend-1

[mohandes]

Comparing DS0008.bmp in #1042 with DS0010.bmp in #1044, you, and only you, know what you did to make the change. That is what you need to undo.


I did not tell you DS0008 was bad, I said that it might possibly be improved. But then you broke it and just want to cry about it?

i say why ??
why when i added damping R my figure like DS0010.bmp and dont like wilson ( have not over or under damp )
maybe i angry some time and not crying !!!
yes you say me it is ok but i want to have under damp ,and i never have this , so properly some where is wrong ?
regards ( and dont angry just laughing because you are my friend )

[porkluvr]

so what am i do ,,,please any one say me my problem (maybe not )
regards

Comparing DS0008.bmp in #1042 with DS0010.bmp in #1044, you, and only you, know what you did to make the change. That is what you need to undo.


I did not tell you DS0008 was bad, I said that it might possibly be improved. But then you broke it and just want to cry about it?

[mohandes]

It looks like you went from "maybe OK" to "very bad". Put it back the way it was.
I think you will never get good sensitivity with OP27.

so what am i do ,,,please any one say me my problem (maybe not )
regards

[porkluvr]

hi
thanks
i put more res ( damping res ) but all time i have not same wave like wilson or i have not never over damp and under damping.
i ask this question many time ago and all laughing to me or dont attention , but again i ask and ...
just some guru and friends help me
i change many coils and any thing to perform over damping but i can not.
please guide me
look when i add the damping R my wave like this and i have not over damp
[ATTACH]27461[/ATTACH]

regards

EDIT :
can i use op27 , i think more better??

It looks like you went from "maybe OK" to "very bad". Put it back the way it was.
I think you will never get good sensitivity with OP27.

[mohandes]

The picture you are comparing your waveforms to indicates an under-damped condition (damping resistor too high).

A small amount of under-damping is nothing to worry about, however the under-damping in that picture does appear to be excessive.

Your NE5534-6 shot shows -maybe- (and only maybe) some over-damping (damping resistor perhaps slightly too low). The best way to know if it is over-damped is to compare that waveform with what you get with a higher value resistor.

Try a higher value damping resistor, maybe 360 or 390 ohms. Keep going higher and higher until you see a slight upward hump develop (indicating a slightly under-damped condition). You would want to either keep that resistor, or go back to the previous, lower, value. Choose whichever damping resistor gives the best sensitivity.

Also, you have noise and it looks excessive but I have no way of knowing for sure. If you have another NE5534 you could swap it in and see if it makes any difference.

When you stick your finger next to the damping resistor, you add capacitance to the circuit which upsets the circuit. Why would you want to do that?

I have a request. Would you please refer to the damping resistor as "damping resistor", instead of calling it "resistor parallel the coil". We know what a damping resistor is. Quit babbling.

hi
thanks
i put more res ( damping res ) but all time i have not same wave like wilson or i have not never over damp and under damping.
i ask this question many time ago and all laughing to me or dont attention , but again i ask and ...
just some guru and friends help me
i change many coils and any thing to perform over damping but i can not.
please guide me
look when i add the damping R my wave like this and i have not over damp


regards

EDIT :
can i use op27 , i think more better??

[porkluvr]

The picture you are comparing your waveforms to indicates an under-damped condition (damping resistor too high).

A small amount of under-damping is nothing to worry about, however the under-damping in that picture does appear to be excessive.

Your NE5534-6 shot shows -maybe- (and only maybe) some over-damping (damping resistor perhaps slightly too low). The best way to know if it is over-damped is to compare that waveform with what you get with a higher value resistor.

Try a higher value damping resistor, maybe 360 or 390 ohms. Keep going higher and higher until you see a slight upward hump develop (indicating a slightly under-damped condition). You would want to either keep that resistor, or go back to the previous, lower, value. Choose whichever damping resistor gives the best sensitivity.

Also, you have noise and it looks excessive but I have no way of knowing for sure. If you have another NE5534 you could swap it in and see if it makes any difference.

When you stick your finger next to the damping resistor, you add capacitance to the circuit which upsets the circuit. Why would you want to do that?

I have a request. Would you please refer to the damping resistor as "damping resistor", instead of calling it "resistor parallel the coil". We know what a damping resistor is. Quit babbling.

[mohandes]

Mohandes , Barracuda is simple detector. You can do two settings:
1. This potentiometer 2,5k and antennna.

2 . Between 1 and 8 pin NE 5534 on the board has a trimer. Get a multimeter , put it on 20 volt range and hung it on the leg 6 of 5534 and minus power . Then trim make multimeter readings to reach zero volts.
3 . Listen to the advice of Porkluvr and after the measured value of the potentiometer put in its place a constant resistor.

If after these settings the detector has low sensitivity, the reason is not looking in the settings. Looking for a reason to use elements with different values than shown in the scheme. Check the right connection of the diodes.

Wakko, you don't have to apologize to me. You would find out soon enough about the differences (ummh, they're both N-channel FETs but that is where most of the similarities end).


Mohandes, you must get rid of the 2.5k pot and select a fixed value resistor. A potentiometer rated for 1W (for instance) can not survive for long if the wiper is turned to only 25% when that 25% section is forced to dissipating 1W. The 1W rating is meaningful only when the entire resistive material is used.

In other words, if you were to use only a 25% section of the pot's resistance and then dissipate 1W in that 25%, you will have overstressed the pot by 4X! When you overstress resistive material it will change value (often dramatically, or just go open circuit.

Mr porkluvr and Torros
i dont know why i have not the same like

look my pics and i use 330ohm 2w
first channel yellow another is blue wave
ne5534-3 ,ne5534-6

40106-2

coil

2n2222

and the final is inceridble when my fingers parallel to the R parallel the coil have a this shape , why??

[mohandes]

thanks Mr Porkluvr and Toros
i use this pot
i chage it by 330ohm 2w.
regards

[Toros]

Mohandes , Barracuda is simple detector. You can do two settings:
1. This potentiometer 2,5k and antennna.

2 . Between 1 and 8 pin NE 5534 on the board has a trimer. Get a multimeter , put it on 20 volt range and hung it on the leg 6 of 5534 and minus power . Then trim make multimeter readings to reach zero volts.
3 . Listen to the advice of Porkluvr and after the measured value of the potentiometer put in its place a constant resistor.

If after these settings the detector has low sensitivity, the reason is not looking in the settings. Looking for a reason to use elements with different values than shown in the scheme. Check the right connection of the diodes.

[porkluvr]

Wakko, you don't have to apologize to me. You would find out soon enough about the differences (ummh, they're both N-channel FETs but that is where most of the similarities end).


Mohandes, you must get rid of the 2.5k pot and select a fixed value resistor. A potentiometer rated for 1W (for instance) can not survive for long if the wiper is turned to only 25% when that 25% section is forced to dissipating 1W. The 1W rating is meaningful only when the entire resistive material is used.

In other words, if you were to use only a 25% section of the pot's resistance and then dissipate 1W in that 25%, you will have overstressed the pot by 4X! When you overstress resistive material it will change value (often dramatically, or just go open circuit.

[mohandes]

Porkluvr - Apologies, it was the J113 I was considering and not the 2SJ113. I automatically assumed that they had left out the '2S' on the part number as they sometimes do. I know Silverdog provides 2 different FETs in his Bara kit, not sure why if it's best that they are a matched pair especially as the MPS102 has a large Vgs(off) rating of -8V MAX compared with the -4V MAX of the 2N5485.

Mohandes - Strange how the BF256B is listed as an equivalent but you've not had much luck with them. Did you use a matched pair? Also I think I remember reading in the forum that you connect the POT in series with a 220R resistor and then adjust it for best damping. The overshoot you're seeing does imply that its under-damped because the damping resistance is too high.

hi wakko
i use j113,bs170,2n3819,bf256,bf256b,bf245b,bf245c and for all the same .
and about the pot the parallel to the coil i use 2.5k pot without the series 220 ohm .can you tell me more to find my problem
and thanks you Mr tepco
regards

[wakko]

Porkluvr - Apologies, it was the J113 I was considering and not the 2SJ113. I automatically assumed that they had left out the '2S' on the part number as they sometimes do. I know Silverdog provides 2 different FETs in his Bara kit, not sure why if it's best that they are a matched pair especially as the MPS102 has a large Vgs(off) rating of -8V MAX compared with the -4V MAX of the 2N5485.

Mohandes - Strange how the BF256B is listed as an equivalent but you've not had much luck with them. Did you use a matched pair? Also I think I remember reading in the forum that you connect the POT in series with a 220R resistor and then adjust it for best damping. The overshoot you're seeing does imply that its under-damped because the damping resistance is too high.

[mohandes]

MY friend i think you see my different figure in pin6 ne5534 to your figure check these :





and my low detection UPSHOT this pics(dont like your pic)
I think the problem in mpsA13

can you send me value and pics about bc517???

can i replace it by bc337 or mpsa25

thanks and sorry me

please see the pics
i think my error from bf transistors but i now have bf245c and dont work well.
when i connect the pot instead of R parallel to coil i have not the same fig like wilson why ???
any think is correct so where is the wrong ? Mr tepco help me before but i can not find it.
regards

[mohandes]

hmmm
i have bf256b
but not work well, i use again them , maybe work better

[Koala]

A few people sell them all ready matched.

Saw some after I ordered mine lost the link it was a major distributor. Plenty of private people sell matched fets for audio and guitar projects.

found this http://www.generalguitargadgets.com/...mart&Itemid=45


This was just the first google came up with there were others on http://www.diyaudio.com