BARACUDA-Legend-1

[Wilson]

Hello Bion, is missing the CI ICL7660SCPAZ on board?
Before connecting the circuit to make a review of all the parts and also the welds, make sure no short circuit between tracks and islands, only then turn and check the voltages-5V and +5 V. Centralize Trimmers & potentiometers, adjust the zero volts DC on pin 6 of the IC NE5534. The coil has to be away from metals. Use a coin to move over the coil and adjust the delay on the potentiometer. Make adjustments to achieve the greatest distance between the currency and the coil. Adjust the potentiometer also Treshold threshold for audio.





Hola Bion, falta la CI ICL7660SCPAZ a bordo?
Antes de conectar el circuito para hacer una revisión de todas las partes y las soldaduras También, asegúrese de que el corto circuito entre las pistas y de las islas, sólo entonces la vuelta y comprobar el voltaje-5V y +5 V. Centralizar activadores y potenciómetros, ajustar el cero voltios DC en el pin 6 del IC NE5534. La bobina tiene que estar lejos de los metales. Utilice una moneda para moverse sobre la bobina y ajustar el retardo en el potenciómetro. Haga los ajustes para lograr la mayor distancia entre la moneda y la bobina. Ajuste el potenciómetro También umbral Umbral de audio.

[bion]

If something is wrong in the picture tell me please.Now mi little problem is the adjustment (i don't have osciloscope).I know just NE5534 pin6-0 volt from offset balace 25k but nothing more.Excuse mi poor inglish(sometimes i use google translator)
Thanks all.

[bion]

Be very carefull that you get the correct pins in the pcb holes.

[ATTACH=CONFIG]26331[/ATTACH]

Thanks 6666

[6666]

Be very carefull that you get the correct pins in the pcb holes.

[bion]

I dont find 2N2222 but i have PN2222, is ok?

[bion]

Thank you very much Wilson.

[Wilson]

Hello Bion, is attached configuration of my barracuda.

[bion]

Problem with transistors



Hello everyone. I have almost finished my Baracuda but I have very difficult with transistors and integrated. I replaced some transistors: MPF102 with BF245 C and MPF meeting BC 517.No A13 with 2222 BC and the 2N5485. I need help I can put as 2222 and 2N5485 ?please Thank you very much.

[Wilson]

Wilson you are correct. Pictures are better. It is harder for me because I do not have digital scope so I must take pictures. Bernie, that is a pretty good capture. If you make it 2 times as big it would be even better!
if you go to the Tektronix.com web site there many items to help you.
i think you can get them in your native language.

http://www.tek.com/downloads

Hello old car, do not worry, if you have no images recorded no problem I trust your opinion about my pictures posted.
Thank you.
Hug.

[Old cart]

Wilson you are correct. Pictures are better. It is harder for me because I do not have digital scope so I must take pictures. Bernie, that is a pretty good capture. If you make it 2 times as big it would be even better!
if you go to the Tektronix.com web site there many items to help you.
i think you can get them in your native language.

http://www.tek.com/downloads

[Wilson]

Hello Old Car and Bernte_one, thank you for all the tips you sent, I have a little trouble understanding some explanations and I believe you also have trouble understanding me. I use google translator and I believe it is not ideal for technical texts. Anyway I will strive to understand more and more. I think the ideal would be to attach the images of pulses in question together with the explanatory text for better comprehension technique to minimize the difficulties of different languages. I do not know if you agree with this thought of mine. Anyway I thank everyone in this forum to exchange information.
Hugs.

[bernte_one]

hello wilson

something like this? make a screen capture some seconds ago with an untested coil

[Old cart]

Damping adjustments

In this case 330 ohms should be pretty close.

I like to adjust the damping resistor by looking at both the output of the preamp AND the voltage across the coil at the same time. Some tips:

1 Make sure your scope probes can take the voltage of the fly back pulse which can be hundreds of volts. Most x10 probes can do this.
2. Ground both probes to the same point on the detector near the coil attachment point and use shortest leads possible.
3. Adjust the scope attenuators and offset/position controls so the waveforms fill the screen vertically as closely as possible.
4. Adjust the time base so once cycle of the transmit waveform fills the screen. Later you may want to zoom in and observe just the fly back pulse to tweak it the best.
5. Use bandwidth limiting. The lowest bandwidth is best as long as it is greater than 2MHz or so. Most hobbiest scopes have 20 MHZ bandwidth limiters and they should be left on most of the time for detector work.
6. Trigger on the start of the transmitter pulse using the -/+ slope and trig level controls. Also use normal triggering NOT auto.
Adjust trigger level so there is no jitter.

7. Do not move probes around or change setting at all unless the waveforms goes off the screen.

While looking at both waveforms adjust the damper r slowly until you see a smooth transition with no ringing and the narrowest ring back pulse at the same time. You will also notice the output , pin 6 , of the preamp at this same time interval will also become narrower and wider while you adjust dampening. You want the setting that produces the narrowest ring back (fly back) pulse and little or no overshoot And the narrowest preamp output. This will allow you decrease the sample delay to its minimum, but no less than 10-12 uS if you want fine gold. On photo 6 if the yellow waveform is the early sample pulse you can decrease the delay 4-5uS so the leading edge of the sample pulse coincides with the point where the preamp out just breaks from the lowest level. You can also shorten the sample pulses to 10-15 uS if you want maximum gold sensitivity.SMALL adjustments to the offset can also help eliminate the wrinkles you see in the preamp out and smooth the response of the detector.

These settings let me increased my depth on a small mans gold ring of 6 grams from 24 to 30 cm. so careful setting pays back with huge rewards.

One last thing, once you confirm these setting are good in the field. Then it is best to replace the adjustable pot with a fixed resistor or combination of resistors that is closest to the measure value of pot. Be careful to keeps the leads as short as possible. You have to remove the pot from the circuit before you measure it so be careful not to disturb the setting you have been so careful to make.

Good luck!

[Wilson]

Actually the last waveform (red one) is the best damped. This shows also a different yellow waveform and the settings have been changed so it is a little confusing. Looks like something less than 350 ohms would be about right.

Hello old car, the figure you said that red is pin 6 NE5534 I forgot to identify the value of resistor damper, I used the original value 330homs ok.
The last picture refers to pulse the MOSFET on the coil reaches around 246VPP.

[Wilson]

Hello Bernte_one you have picture of the waveforms of your barracuda to post?
Thank you.

hello wilson

nice diagrams
if i understand right 420R iss the best value for your coil
or how would you interpret the waveform form pulse signal?

Hello Bernte_one you have picture of the waveforms of your barracuda to post?
Thank you.

thanks