redesign of tiny from pulsdetektor.de

[bernte_one]

and what was the solution for your Problems?

[heyran]

thanks guys... i built tiny successfully and it works quiet well

[heyran]

this is my tiny board
https://drive.google.com/file/d/0B-0...ew?usp=sharing
i didn't find hef4053 and use cd4053be instead . i dont know why my tiny got repeated beep (something like clicking) and cant detect any metal with coil.

[heyran]

thank you... i have some problem with this MD ...i used irf9640 and also a potentiometer instead of R1, but it gets warm and does not work... my md can't detect any metal... please help

[kt315]

look on schematic and you will see 24V 1.5Ah

[Geo]

Any battery 12V with capacity >1200 Mah is ok.
Detector needs 120ma.

[heyran]

hi guys, do you know what kind of battery is suitable for this MD, I mean in terms of voltage and current... THANKS

[zomby]

Hello Do 3-3.5 ohm coil 300-350 mikroHenri and follow the scheme. Everything will be fine

[timbo]

Did a other test this morning.
at first it clicked like the first time and than sudenly only a high stedy
tone. No adjusment posible. I also smeld something burned but I dont see anything
thats fried. I was hoping on building a underwater detector from this design but maby
I schould by a complete kit from silverdog. I do have an extra pcp. Maybe I should
restart from scratch. Normaly when I follow the design it must work no?

[timbo]

Hello tepco,

I think I build the original version,the analog.
The mosfet is the original,MTP2P50EG
I dont have a scope just a multimeter.
What do you mean with the 555 driver and everything arround mosfet?
You mesioned in your older post that the resitance of R1 is to much,what would be a better value?

regards

Tim

[Tepco]

I can hardly remember exact Minipulse circuit now, it was long time ago, but few more info about your version may be useful. What version of it you built, old analog one (4538 timing) or newer version (crystal)? Pulsdetektor website changed somewhat in meantime, projects too, I built older version, but don't have schematics at hand right now. Also, what type MOSFET you use? Detector is built for P type, original one is hard to find, use IRF 9640 instead. If you install wrong type, like IRF740 or something similar, N type, this can be major problem. Transistor will be ON all time, current flowing thru reverse body diode, producing abnormal current consumption, now limited just by coil resistance, then voltage across transistor will be about 0.9V, not across coil, and lot of heat. Check transistor type, and current consumption, with and without coil connected. Should be over 100mA with coil, something very small, around 20mA without. If abnormal, check 555 driver and everything around MOSFET. Most important, do you have access to oscilloscope? You will need to build proper coil for this (or at least improvise something, just hit 250-400uH inductance and not too thin wire, few Ohm) , then make adjustment (dumping resistor and all). 1000uF instead of 10000 will not mess up anything, actually more chance is to blow up something with larger cap in case of malfunction. I cant remember details, but just about every Pulsdetektor schematic is somewhat “boobietraped” to some degree, intentionally or not, making it nice learning project until you make it work. When it does, lovely little machine is not bad at all.

[timbo]

Hello,
I am new to the forum and hope someone of you more experienced builders could help me(bernte_one,Tepco)

I know this is an older thread but I am building a Tiny detector.
I finished the build an started it up for the first time today.
I got the clicking sound and I can tune it to a slow steady click but it
does not detect metal. I did not make the coil yet so I used one of a other project
to test it. This had a 7 ohm resistance,I did not know it needed to be between 2,5 and 3,5 ohm.
Did I broke something this way? I mesured the voltage to the coil and its only 0,9 volts.
Is this not to litle? On the very first run I also made a mistake with the capacitor. I miscounted a zero,
1000 instead of 10 000. I rapidly changed this but did this break something?
I did study electricity in school but electronics I dont have much expiriance with.
Could someone point me in the wright direction to solve this problem?

most Regards

Tim from Belgium

[Astromic]

I finish to buillt Tiny MD but i dont find Q1 MOSFET and i replaced with IRF840, so i have clicking but Q1 get very hot in fw seconds.I need help please.

how "hot"?
it's normal to get a bit worm sometimes, but excessive heat would toast it easily..
re-check both the datasheets and compare the heat specs, and if required you can attach a large heat sink.

[bion]

Tiny

I finish to buillt Tiny MD but i dont find Q1 MOSFET and i replaced with IRF840, so i have clicking but Q1 get very hot in fw seconds.I need help please.

[$hooter]

hiiii

this's all info about search coil, can be useful.


*Size********Shape**Turns******Wire size *******Inductance***Resistance

Ø 120 mm***** Round***36*** Ø 0.40 mm / 0.14 mm2*** 405 µH******1.9 Ohm
Ø 150 mm***** Round** 31*** Ø 0.40 mm / 0.14 mm2*** 394 µH******2.0 Ohm
Ø 175 mm* ****Round***28*** Ø 0.40 mm / 0.14 mm2*** 387 µH******2.1 Ohm
Ø 200 mm***** Round***26*** Ø 0.40 mm / 0.14 mm2*** 406 µH******2.2 Ohm
Ø 250 mm***** Round***22*** Ø 0.40 mm / 0.14 mm2*** 380 µH******2.3 Ohm
Ø 300 mm***** Round***20*** Ø 0.50 mm / 0.20 mm2*** 390 µH******1.6 Ohm
Ø 400 mm***** Round***17*** Ø 0.50 mm / 0.20 mm2*** 396 µH******1.8 Ohm
Ø 500 mm***** Round***15*** Ø 0.50 mm / 0.20 mm2*** 400 µH******2.0 Ohm
1.0 x 1.0 m**** Square** 10***Ø 0.66 mm / 0.34 mm2*** 406 µH******2.0 Ohm
1.4 x 1.4 m**** Square***8*** Ø 0.66 mm / 0.34 mm2*** 387 µH******2.2 Ohm
1.8 x 1.8 m**** Square***7*** Ø 0.80 mm / 0.50 mm2*** 398 µH******1.7 Ohm