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Beware, these fake devices are also available smd package. Haha!
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Also they have been selling fake dual triodes, pentodes etc. Just reprinting the writing on glass of RF class triodes etc. For triodes like c12ax7,12au7,etc. Which are highly sought after for vintage audio equipment.
Unbelievable!Comment
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Fake Tubes??? It just remind me joke friend of mine told me. The heaven, the earth and the human are made by God. Everything elese is made in China.Comment
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Originally posted by nonkapo View Post
They are real genuine tubes but for RF applications( very high frequency), so they are not suitable for audio application like audio amplifier etc. So they Rub off old writing and put new fake print.Comment
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Go eBay check prices for vacuum tubes. They are valuable, especially the old stock.Comment
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Quick question again. Untill i'm waiting the Oscope to arrive i've noticed KT315 doing some measurements with the Frequency counter. So accept measuring generator friquency what else i can use my simple counter for when setting up Surf PI? Is it really worth trying it or not?
Thanks.Comment
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Since no one comment i try measuring the frequency at pin 3 of the 555 timer. With the given components(22nf, 3k3,100k) it should have a 614 herz frequency and 1.57 milliseconds timing. However i'm getting reading of 590HZ and 1,66 timing. Is there a point to adjust the frequency to match exactly 614Herz? I've seeng a mod of Dennis where he adjust that by 5k pot connected in series to 3k3 resistor, but that will only decrease the frequency and timing. Any suggestions? Thanks.Comment
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What are you trying to achieve nonkapo as 590hz /1.66 is acceptable (less that 25hz) i would not bother to change it as it will not make any measurable difference.Comment
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Why do you want to have exactly 614 Hz?
Change R1.
There should also be online calculator for Ne555.
The values for R1 / R2 and C must be correct!Comment
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Well trying to achieve those 40cm for one euro coin which I can't achieve even with the bigger 2 euro. Also trying to see if one can troubleshoot with frequency meter if no oscilloscope is there. In this case if the frequency is not critical, the pulse width definitely is. So as per me that changes from the same components isn't it? But I think there is not much more to be done with this part of the circuit. The fet, coil and the receiving part need more attention.
To Andi - yes that's what I'm using. So either my MM is not calibrated or the tolerance of the parts is wrong.Comment
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Where did you hear 40cm for one euro on the surf pi pro ? i get 1pound (similar coin) at 25cm and am happy my goal is better sensitivity to silver and gold alloys by shortening pulse width and using faster coil.
Do you get a lot of buried Euros where you live if so they will not be very deep as quite modern coins?Comment
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Thats just a reference mark. There are no euros here at all (UAE;-). Have a look at this: https://www.youtube.com/watch?v=-jsbQ11ZBQE
The strange part is that unlike in the Surf PI Pro here only the resistor and capacitor in the Feedback od LM358 are changed,when in the original schematic both are changed to 470k/220n. The other thing is no syncro between 555 and 7660 and the ceramic cap on 555 removed. Also 100p added on the negative inn of 5534. Look at the circuit it may talk to you more than it did to me:
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Other rewieu?Comment
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Hello everyone
I have done pro surfmater
On pin # 5 of icl 7660 there is no -5V instead there is 0.56v
I have substituted icl7660 for two others and it varies between 0.46 and 0.52v
Can someone help me with this?
Thank youComment
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Try Putting a Diode (1N4001 or Similar) in parallel with C13.
Anode to Pin 1.Comment
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