ATiny-4

[Geo]

Thanks Oscar.
Regards

[Geo]

Hi. I think that it is better to write here the problems of the ATtiny4 so some other time to know where to looking for it.
I changed the coil and with a very critical regulate of the gain, TRS and Delay i have better results but not good.
With a coil of 25 cm diameter (400uH, 0k5...1k...2k damping resistor) i detect
a 2Euro coin at 20cm max
a soda can at 50cm max.
I use a IRF840 and not the IGBT BUP213. Can someone tell me if this is a problem and why????
The peak pulse voltage is 500V
The power suplly is 21V
Any idea??
Regards

[1843]

HI Geo,

What is the output voltage of the HCPL? If you limited it to under 20V, it causes no ploblem.
Your coil is not good for this PI, You should use a 26cm coil with 45turns of 0.7mm wire or increase the preamp gain to 1000.
My Minediver-2 can detect a soda can at 65cm. A 2cm coin at 22cm.
Regards

[Geo]

Hi 1843.
I will check the output of 3120 and i write to you.
About results....
Also results of your Minedriver2 are not good.
I say this because Delta Pulse with less gain and less power has better results. At coins the DP detect a 2Euro at 28...30cm with a 25 cm coil.
So where is the problem at PulseDetector Machines????
I wait from ATtiny4 to detect a 2euro coin at bigger distance than 30 cm.
The gain of preamplifier is x1000 (560k/560R).
Slowly - slowly we will make it
Regards

[1843]

Hi Geo,

I think that its gain is 540 ( 560K/470+560).

Minediver detects the coin with 60us sample delay. it is good. second sample is 500us for Minediver.

Regards

[Geo]

Hi Geo,

I think that its gain is 540 ( 560K/470+560).
[ATTACH]4330[/ATTACH]
Minediver detects the coin with 60us sample delay. it is good. second sample is 500us for Minediver.

Regards

Hi 1843
Because there is the diode zener, the first resistor with coil and zener are as a voltage source, so the gain is 560k/560r.
This is my opinion , so i wait the opinion and from other guys.
At ATtiny second sample is 100us after the pulse of first sample. I am afraid that this maybe to produce problems at the performance of the detector.
Regards

[1843]

Hi Geo,

I am not an electronic expert...But my opinion is that the coil signal is the voltage source not the first resistor and zener...
The 100us second pulse is wrong... at least should be 500us! ATiny-4 is a deep seeking PI.

Regards

[Geo]

Hi 1843.
Now i have better results. With the coil of DP (1000uH) i detect a soda can at 80cm, a 2Euro coin at 30cm, and a 50 Euro-cents at 28cm, with the sample delay at 30us.
Today i will try to change the gain of the preamplifier and to put a trimer for null the offset voltage. Also i would like to construct a coil a NormanB show at PIU threa. I believe that i will gain more depth with a coil that match to the detector. Have you tried different coils to your minipulse? and did you found difference at the total performance of the detector????
Also i want from the other specialists here to tell me who is the difference if i will use IGBT transistor as the schematic show. Now i use a IRF840
Regards

[1843]

Hi Geo,
For the coils of 1 to 1.5mH the preAmp gain is ok. I said increase the gain for the 400uH coil.
I don't have Minipulse but Minediver. I tried two coils on it. one 1m x 1m 16Turns of 1.2mm wire. abut 1.2R, excellent detection! and one 17Turns of 1mm wire about 1.8R... Not so good.
I suggest you to keep the coil resistance below 1.5ohms.
I hope the your Atiny becomes better....!

Regards!

[Geo]

Hi 1843.
Thanks.
I use IRF840 for TX, so it is not a good solution to use a coil of 1.2 Ohm. I try to find the IGBT BUP213, so then maybe to try a coil with low DC resistance. I forgot to tell you that my ATtiny is not very stable
Every one or two minutes it needing a fine tuning. Delta pulse with automatic tuning was perfect. I think that Sisco had the same problem. Do you know anything about it?????
And did you tried the AD844 ?????????
regards

[1843]

Hi Geo,
I think that the instability is about your MOSFET. Does it gets too hot? What voltage is its gate driver pulses? under 20V?

I use AD844. Very stable!

Regards!

[Geo]

Hi Geo,
I think that the instability is about your MOSFET. Does it gets too hot? What voltage is its gate driver pulses? under 20V?
I use AD844. Very stable!
Regards!

Hi 1843.
I made a new coil but i did n't tried yet. I spent my free time with the Pistol Detector.
I believe that the instability is around the preamplifier. IRF840 is a little hot after one hour (for me works at a normal condition). About the gate voltage.. here maybe to there is a problem. Gate voltage is as the power supply 19.... 21V. I will try to reduce it and i will write.
Regards

[1843]

Hi Geo,
So the problem is due to the your damaged MOSFET!
Reduce the gate driver voltage to 15V and use a healthy MOSFET.

Best Regards

[Geo]

Hi Geo,
So the problem is due to the your damaged MOSFET!
Reduce the gate driver voltage to 15V and use a healthy MOSFET.

Best Regards

Hi 1843
Mosfet is not damaged. Of course a reducing at the gate voltage it is nesessary. But the best solution is to find the IGBT transistor. Today i tried with NE5534 and i had better operation, better stability anb a little better depth!! After 2 days i will go to Athens and if i have free time i will looking for AD844 and the BUP213.
Regards

[1843]

Hi Geo,
The IRF840 maximum source-gate voltage is 20V and you have run it with 21V...
AD844 is very good, I recommend it.

Best regards