The IRF640 is getting hot

[Sean_Goddard]

Or get a bigger phone.

OK I was going to say one word...AVALANCHE!!!

But then I read this. Well I've done it now and got it out of my system.

(Yes I'm on a PC, yes I can see the date but you never know). << Me most days.

[Qiaozhi]

Ha ha ha ha ha going to have to get bigger fonts on my phone

Or get a bigger phone.

[marburg]

Ha ha ha ha ha going to have to get bigger fonts on my phone

[Qiaozhi]

Hi was having same problem on silverdog pi but was using small 100mm coil once i made 250mm coil and fitted it to the board it was fine picking up 2p coin at 200mm but only 80-100mm for 1gram of gold

Do you know that you're replying to a post from almost 4 years ago?

[marburg]

Hi was having same problem on silverdog pi but was using small 100mm coil once i made 250mm coil and fitted it to the board it was fine picking up 2p coin at 200mm but only 80-100mm for 1gram of gold

[yhl]

HELP

Who can help me? My current small Gary detector only 55 mA. Do not know what is the problem

[danny475bek]

hi

are you using the the reg111 on the bord or the lm1117 as a high curent transistor regulator
if you are using the second one the big transistor type the irf will make some het and you can reduse that by ataching some matal or i prefer alaminium stripp on the irf
if this is not the problem it migt be that the reg is not working well you know there is a short and a cutt of and the open situwation it might be opened that mean that the full power is entering to the pcb
you have to check the resistors they can be functioning wrong espesialy the resistors that are neer to the irf
tc
danny

[hisoka147]

Warning

Don't touch the ground or back plate of IRF640 or you'll experience some electric ground shock.

Anyway, It's nice to know that Gary is back and answered most of my concerns. The problem lies on to much current that I'm using.

[Alexismex]

Hello ,
check your pulse with oscillo, perhaps the primary pulse is very wide.... or your pulse frequency is very high...

[silverdog]

Hi all

I am also building Gary's Pulse 1 and am experiencing a very hot irf640, too hot to touch - any further thoughts on why ?
my unit is yet to work though
I have checked datasheet of irf640 and pinouts are the same so problem must lie elsewhere

Anyone got a good explanation of schematic ?

[Aziz]

Hi hisoka147,

the drain and source pin of the mosfet might be exchanged! So the inherent forward biased diode of the mosfet might conduct allways.
Check this please.

Aziz

[chemelec]

I finally completed the board and already soldered all the parts. Upon testing, the IRF640 is getting hot. I just want to ask if this is normal.

Sorry for the Delay in Responding, I have been away in Chile, Argentina and Brazil, on a holiday

It should Not get Hot at all.
Unlikely Even Warm!

AVERAGE Current Flow is Less that 100 mA. on that 18 Amp Mosfet.

Working or Not, Sounds like you have a Problem!
Check Input Current. Should be Less than 150 mA.

Gary

[hisoka147]

What a co-incidence. This is the information that I'm trying to seek for some time and luckily, you've shared it to me. I have'nt read the whole content yet and simply browse the whole idea and it's very nice.

Thank you for sharing mate!

[WM6]

I'm trying to avoid touching this component because I experienced some electric shock on it.

Shock could be curative. Actually this is sort of Zapper stage. Read more about Zapper on web, e.g. this:

http://www.littlemountainsmudge.com/zapperrevisions.htm

http://www.toolsforhealing.com/Products/Zapper/Articles/WhatisaZapper.html

[hisoka147]

Thanks

Either way the circuit is fully working and I placed a small heat sink for this component (IRF640).

I'm trying to avoid touching this component because I experienced some electric shock on it.