Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dc05.r1000.mx.aol.com (Internet Inbound) with ESMTP id DA305380000BC; Tue, 9 Apr 2013 11:22:31 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UPa3Y-0000yQ-28 for rs_out_1@blacksheep.org; Tue, 09 Apr 2013 16:01:56 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UPa3X-0000yG-Ee for rsgb_lf_group@blacksheep.org; Tue, 09 Apr 2013 16:01:55 +0100 Received: from mail-oa0-f41.google.com ([209.85.219.41]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1UPa3V-0003vU-4a for rsgb_lf_group@blacksheep.org; Tue, 09 Apr 2013 16:01:54 +0100 Received: by mail-oa0-f41.google.com with SMTP id f4so7640360oah.0 for ; Tue, 09 Apr 2013 08:01:31 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=M3ybxPkDETg1C10pqtrZ7CcSKnykowhYlaJRPiR9pqc=; b=WY50WUy/5DKmI9Fhxz5xT8A6UFpH1DZHJwNg9BfBDrrj6HUy4oXRqoPQCJP/6JCK7p HiYwW0tHBhWr6tRnft2q7P3BWOyob2Mod60okRpqpVvQ+kl0D7OimZt9iW2+/O41hcD5 g3FLP7a6N+Qrj+qLxkmu0kpd7D9oSGCCExqwuWOV4xZqR9fyOrq3vFqW8I6hIjLO/dlL /EI0m+84f3MZlwiMP7EM3sdXzzJZjn5RQRoOZMxefS1ru1Ki7HLCrxezesOSx+19tZug ETIExG94yDvJ9akP5u7qXYIJTwPc4LkoyphYuELMWLbIx+K1rwhzb5+CwoqmsdtDGF/G CotQ== MIME-Version: 1.0 X-Received: by 10.60.62.166 with SMTP id z6mr18278855oer.54.1365519691260; Tue, 09 Apr 2013 08:01:31 -0700 (PDT) Received: by 10.60.135.199 with HTTP; Tue, 9 Apr 2013 08:01:31 -0700 (PDT) In-Reply-To: <7E7DFBB4D102A04DB5ADC88D66628A4A0FB994BD@ICTS-S-MBX5.luna.kuleuven.be> References: <7E7DFBB4D102A04DB5ADC88D66628A4A0FB994BD@ICTS-S-MBX5.luna.kuleuven.be> Date: Tue, 9 Apr 2013 11:01:31 -0400 Message-ID: From: Warren Ziegler To: rsgb_lf_group X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Thank you Rik, good ideas! Warren On Mon, Apr 8, 2013 at 4:12 PM, Rik Strobbe wrote: [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.219.41 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (wd2xgj[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_OBFUSCATE_05_10 BODY: Message is 5% to 10% HTML obfuscation 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 14522a7d8bfffcae5e92e35059f18ae1 Subject: Re: LF: Re: Hall Effect for Over-current shutdown? Content-Type: multipart/alternative; boundary=047d7b67266e21abd804d9eed485 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNSAFE,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-dc05.r1000.mx.aol.com ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d40855164323725d3 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --047d7b67266e21abd804d9eed485 Content-Type: text/plain; charset=ISO-8859-1 Thank you Rik, good ideas! Warren On Mon, Apr 8, 2013 at 4:12 PM, Rik Strobbe wrote: > Hello Warren, > > > > that should be possible, I have used a A1302 Hall sensor as a "nocontact" >100A > current monitor. > > The sensor was just some mm away from the wire and was calibrated once > using a (expensive) amp. meter. > > At lower currents it might be better to let the wire run a small loop withthe sensor inside > . > > The output voltage is proportional to the magnetic field (= current > through wire) with a offset voltage of 2.5V (at 5V supply voltage). > > Just be sure to get a linear Hall sensor (not the latch type) and be aware > that most Hall sensors are rather slow (some 10..100us response time). Soat 136kHz > it will resond to the average current rather than peak currents. > > > > 73, Rik ON7YD - OR7T > > > > > ------------------------------ > *Van:* owner-rsgb_lf_group@blacksheep.org [ > owner-rsgb_lf_group@blacksheep.org] namens Warren Ziegler [ > wd2xgj@gmail.com] > *Verzonden:* maandag 8 april 2013 21:07 > *To:* rsgb_lf_group > *Onderwerp:* Re: LF: Re: Hall Effect for Over-current shutdown? > > Hi Alan, > > I've modified the G0MRF amp with the M0BMU output configuration, I'm > using a 30V supply. > The G0MRF uses a current sense resistor to shut down the amp quickly in > case too much current is being draw. > I've modified the output transformer turns ratio to produce more power at > lower supply voltages (I'm using 500V, 55a FETs). > However with the new higher currents and with a new appropriate value > sense resistor its developing a LOT of heat (12 W or so) and needs to be > heat-sinked. > I'm thinking Hall-effect might be more efficient and produce less heat - > I'm pretty sure that others have used Hall effect devices to protect MOSFET > amplifier and I'm looking for circuit tips. > > 73 & Tnx! > Warren > > > > > On Mon, Apr 8, 2013 at 2:52 PM, Alan Melia wrote: > >> ** >> Ah interesting problem Warren.... why is it over-current?? if it is >> over-current because a high voltage has welded/melted a short between drain >> and source, then the protection wont help ....high currents usually lead to >> excess heating ......but what is the real cause? If you really need DC >> supply protection would not a high-side current monitor be easier/faster??? >> The problem then could be there is enough energy stored in the PA choke to >> zap the FET before, or even if, you can disconnect the supply. >> >> OK drive fails permanently on might be a condition it would protect the >> FETs against with DC coupled drive >> >> Alan G3NYK >> >> ----- Original Message ----- >> *From:* Warren Ziegler >> *To:* rsgb_lf_group >> *Sent:* Monday, April 08, 2013 7:15 PM >> *Subject:* LF: Hall Effect for Over-current shutdown? >> >> Anyone using a Hall effect device for overcurrent sensing and shutdown >> in a MOSFET amplifer? >> >> -- >> 73 Warren K2ORS >> WD2XGJ >> WD2XSH/23 >> WE2XEB/2 >> WE2XGR/1 >> >> >> >> > > > -- > 73 Warren K2ORS > WD2XGJ > WD2XSH/23 > WE2XEB/2 > WE2XGR/1 > > > -- 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1 --047d7b67266e21abd804d9eed485 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Thank you Rik, good ideas!

Warren=



On Mon, Apr 8, 2013 at 4:12 PM, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote:

Hello=A0Warren,

=A0

that=A0should=A0be possible, I have=A0used a=A0A1302 Hall sensor as a "no = contact" >100A=A0current monitor.

The sensor was=A0just=A0some mm=A0away=A0from= the=A0wire and was=A0calibrated=A0once=A0using= a (expensive) amp. meter.

At=A0lower=A0currents=A0it=A0might=A0b= e=A0better to let the=A0wire run a=A0small loop= =A0with the sensor inside.

The output voltage is=A0proportional to the=A0magnetic field (=3D=A0current=A0through wire)=A0with = a offset voltage of=A02.5V (at=A05V=A0supply voltage).=

Just=A0be=A0sure to=A0get a=A0linear H= all sensor (not the=A0latch type) and=A0be=A0aware<= /a>=A0that most Hall sensors are=A0rather slow (some 1= 0..100us response time).=A0So at=A0136kHz=A0it=A0will=A0resond to the averag= e=A0current=A0rather=A0than=A0peak currents<= /a>.

=A0

73, Rik=A0=A0ON7YD - OR7T

=A0

=A0

Van= : owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org<= /a>] namens Warren Ziegler [wd2xgj@gmail.com]
Verzonden: maandag 8 april 2013 21:07
To: rsgb_lf_group
Onderwerp: Re: LF: Re: Hall Effect for Over-current shutdown?

Hi Alan,

=A0 =A0 I've modified the G0MRF amp with the M0BMU output configur= ation, I'm using a 30V supply.
The G0MRF uses a current sense resistor to shut down the amp quickly i= n case too much current is being draw.
I've modified the output transformer turns ratio to produce more p= ower at lower supply voltages (I'm using 500V, 55a FETs).
However with the new higher currents and with a new appropriate value = sense resistor its developing a LOT of heat (12 W or so) and needs to be he= at-sinked.
I'm thinking Hall-effect might be more efficient and produce less = heat - I'm pretty sure that others have used Hall effect devices to pro= tect MOSFET amplifier and I'm looking for circuit tips.

73 & Tnx!
Warren




On Mon, Apr 8, 2013 at 2:52 PM, Alan Melia <alan.mel= ia@btinternet.com> wrote:
Ah interesting problem Warren.... why is it over-= current?? if it is over-current because a high voltage has welded/melted a = short between drain and source, then=A0the protection wont help ....high cu= rrents usually lead to excess heating ......but what is the real cause? If you really need DC supply protection = would not a high-side current monitor be easier/faster??? The problem then = could be there is enough energy stored in the PA choke to zap the FET befor= e, or even if,=A0you can disconnect the supply.
=A0
OK drive fails permanently on might be a conditio= n it would protect the FETs against with DC coupled drive
=A0
Alan G3NYK
----- Original Message -----
Sent: Monday, April 08, 2013 7:15 PM<= /div>
Subject: LF: Hall Effect for Over-cur= rent shutdown?

Anyone using a Hall effect device for overcurrent sensing = and shutdown in a MOSFET amplifer?

--
73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0



--
73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0



--
73 Warren K2= ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0
--047d7b67266e21abd804d9eed485--