TESORO GOLDEN SABRE

[ivconic]

Dear Ivconic
what are the best replacement for 2n2222 and 2n2907
thanks in advance

Depends where? At what place? I am sure you are asking about TGS so...;
At chopper stage BC557 and BC547 works just fine. Also 2N3904 and 2N3906. BC327 and BC337 also...
At TX, instead 2N2907 you may use BC327. Between TX and 4024, instead 2N2222 any other Uni NPN will do the job just fine. It is just simple buffer. You may use BC546, BC547, BC548, BC337, 2N2904, S9014......etc...etc..

[metaldetector107]

equivalent

Dear Ivconic
what are the best replacement for 2n2222 and 2n2907
thanks in advance

[metaldetector107]

nulling

Dear Sir
thanks for replying me
i have made a test of nulling coil as you described for me
but i couldnot get less than 4.7mv
i spent half a day before it was easy to null as Ivconic way only few seconds
but honsely i belive in your way in nulling but dont tell Ivconic he gets angry very soon
lets see what i done i put 100k GB resistor on mid position
and put a -lead on body and
+lead on pin7 of LF353 is it right??
please if you dont mind explain for me i know you reported many times
just this time again please by the way the result was around 10cm for silver coin 1.7cm ..
Dear Qia the 100k GB is around 96k i tried to get exact value but i could not cuz of resistor tolarance

thanks alot

[Max]

43.9nH !!! Sheeeesh!!! Where to find such small choke!?!?!

Hi,
you just asked for the value... not where you could buy one!

Anyway... I think nH level inductors can be made about easy at home!

Do you remember the induction heating topic...?

Kind regards,
Max

[simonbaker]

43.9nH !!! Sheeeesh!!! Where to find such small choke!?!?!

It should be fine to use bigger choke as long as resistance is very low. You only want to pass DC (zero frequency), so why not use bigger choke and make cutoff even lower?

Regards,

-SB

[ivconic]

Or....let's "humanize" choke value and use some other capacitance in formula, ok?

[ivconic]

Hi,
so I think you mean we need an LC low-pass at 3.5Khz cut-off, right ?

Anything above in frequency will be attenuated by 20db/decade constant slope, ok ?

If so... suppose your big capacitor is 47000uF (47milliFarads) you'll get from forumla of simple LC low-pass that frequency of cut-off is by:

F=1/2*pi*sqrt(L*C)

... so the sqrt(L*C) = 1/2*pi*F

then L= 1/(4*pi^2*F^2*C)

now F = 3.5Khz = 3500Hz

Then L= 1/(4*3.1416*3.1416*3500*3500*0.047) = 4.39E-08

Then L = 43.9nH (about) to get required cutoff.

Kind regards,
Max

43.9nH !!! Sheeeesh!!! Where to find such small choke!?!?!

[Max]

Actually, i was thinking to experiment with more complex filtering;
super cap and small choke.
Now, job is to accuratelly calculate choke for this filter... we have 3.5-7kHz (approx) spikes there.. So choke must cover that bandpass.
Hmmm.... i would not be offended much if somebody help here with choke calculations..!

Hi,
so I think you mean we need an LC low-pass at 3.5Khz cut-off, right ?

Anything above in frequency will be attenuated by 20db/decade constant slope, ok ?

If so... suppose your big capacitor is 47000uF (47milliFarads) you'll get from forumla of simple LC low-pass that frequency of cut-off is by:

F=1/2*pi*sqrt(L*C)

... so the sqrt(L*C) = 1/2*pi*F

then L= 1/(4*pi^2*F^2*C)

now F = 3.5Khz = 3500Hz

Then L= 1/(4*3.1416*3.1416*3500*3500*0.047) = 4.39E-08

Then L = 43.9nH (about) to get required cutoff.

Kind regards,
Max

[ivconic]

A bit better sketch

This is my usuall setup. You may notice that i am using 4-lead cable. It is acting excellent. I made over 30 devices so far using this setup.
Actually...no need for 4-lead cable here. 3-lead cable will do the job just fine. I am using 4-lead cose it is easy to obtain it in local shops, here.

[ivconic]

I had same reaction when I saw it here and I had to buy it: http://www.goldmine-elec-products.co....asp?dept=1028

I know it must be good for something, just haven't figured out what yet.

It would be good for something needing sudden large current draw, like a camera flash. TGSL is pretty steady current. Maybe better for PI detectors. I tried bigger capacitors on TGSL negative supply to try to get rid of voltage spikes, but didn't help - they are too fast, smaller caps work better. Can't seem to improve on TGSL....

I think also might be good for micro-power projects, like solar powered radio beacon, etc.

Very intriguing -- we need separate thread somewhere with competition for most interesting application of this cap.

I'm for it...!

Regards,

-SB

Actually, i was thinking to experiment with more complex filtering;
super cap and small choke.
Now, job is to accuratelly calculate choke for this filter... we have 3.5-7kHz (approx) spikes there.. So choke must cover that bandpass.
Hmmm.... i would not be offended much if somebody help here with choke calculations..!

[Ultimate_Haze]

I have try with cable that ivconic show for Eldorado.Much better stability.I now its not the right one but its best that I can find.
Also do you remember what molzar say.On the original setup coil wirement is diferent!I will try to show with pictures.
With 32ohm small speaker and last mode very stabile and loud sound.
Thanks

[Qiaozhi]

So...this just justify my previous presumtion! It will turn that my question is not stupid at all!

You never ask stupid questions.

[simonbaker]

Dea Qiaozhi MAX Ivco
please how to measure RX frequency without capa and coil calculation
i mean with digital multimeter which has got frequency meter as well
thanks

By RX frequency, I assume you mean RX coil-capacitor resonant frequency.

You need to get a signal generator which can make different frequency sine waves.

You need to connect the output of the signal generator to the RX coil (which is parallel to the capacitor) -- put a 100 ohm resistor in series with the signal generator output also.

If your multimeter can measure AC voltage up to 20000 Hz, you can use it. Otherwise, you need to use an oscilloscope.

Measure the voltage across the RX coil and slowly vary the signal generator frequency from 10000 Hz to 20000 Hz. When the voltage is highest, that is your RX resonant frequency.

Regards,

-SB

[Max]

Yes Quiaozhi, that's the component! I have almost identical here by me.
Acts indeed like real capacitor!
So, i was thinking to wire it up at TGSL and observe behavior on scope. First i would like to wire it up at chopper output. Usually it produces -6.2V +/- 0.5V. So.... hopefully this special capacitor will further stabilize and filter negative rail at TGSL. Will try and see later..
Also, it would be good to wire it up to TX supply also.
Need to be checked.

Hi,
I think it's a good idea... cause will give enormous filtering effect!

Must find some old VCR...

Kind regards,
Max

[simonbaker]

Now is my turn to ask funny question;
have you ever noticed that capacitor-look-like component, usually present in older VCR's? Small component, exactly capacitor look, usually labeled as 0.47F (!!!!) 5V or 6V? Meaning actually 47 000 uF !!! Small...smaller than capacitors we are using mostly here.
So.. i took one recently and wired it parallel with one led diode and ps. Switched on ps and second after switched off. Led diode shined (diming down) for 2 minutes after!!!!!
So...actually it is capacitor. Hell of capacitor! Excellent to stabilize some voltage. So...here is my funny question:
How about, if we use that component(s) in TGSL? On very few places, especially on TX and eventually at chopper output (reversed, respecting polarities there)....ha?!
I asume, it will take a bit of time to charge fully from accu. So, after switching on, detector will be ready to operate after few seconds...
I never had any experiences before with this kind of capacitors....but shure this look like having some potentials to be used here...
I am very interested in your opinion..

I had same reaction when I saw it here and I had to buy it: http://www.goldmine-elec-products.co....asp?dept=1028

I know it must be good for something, just haven't figured out what yet.

It would be good for something needing sudden large current draw, like a camera flash. TGSL is pretty steady current. Maybe better for PI detectors. I tried bigger capacitors on TGSL negative supply to try to get rid of voltage spikes, but didn't help - they are too fast, smaller caps work better. Can't seem to improve on TGSL....

I think also might be good for micro-power projects, like solar powered radio beacon, etc.

Very intriguing -- we need separate thread somewhere with competition for most interesting application of this cap.

I'm for it...!

Regards,

-SB