Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk06.r1000.mx.aol.com (Internet Inbound) with ESMTP id BB29A3800009F; Mon, 8 Apr 2013 16:14:16 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UPIRR-0001g1-9q for rs_out_1@blacksheep.org; Mon, 08 Apr 2013 21:13:25 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UPIRQ-0001fs-Mo for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 21:13:24 +0100 Received: from rhcavuit02.kulnet.kuleuven.be ([134.58.240.130] helo=cavuit02.kulnet.kuleuven.be) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1UPIRN-00010R-RD for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 21:13:23 +0100 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: 30E001280BA.A6000 X-KULeuven-Information: Katholieke Universiteit Leuven Received: from icts-p-smtps-2.cc.kuleuven.be (icts-p-smtps-2e.kulnet.kuleuven.be [134.58.240.34]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id 30E001280BA for ; Mon, 8 Apr 2013 22:12:56 +0200 (CEST) Received: from ICTS-S-HUB3.luna.kuleuven.be (icts-s-hub3.luna.kuleuven.be [10.112.9.17]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by icts-p-smtps-2.cc.kuleuven.be (Postfix) with ESMTPS id 2DB7220041 for ; Mon, 8 Apr 2013 22:12:56 +0200 (CEST) Received: from ICTS-S-MBX5.luna.kuleuven.be ([fe80::312b:f3bc:9c4:4ebb]) by ICTS-S-HUB3.luna.kuleuven.be ([fe80::a470:76b3:406d:2b1a%27]) with mapi id 14.02.0328.009; Mon, 8 Apr 2013 22:12:55 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Thread-Topic: LF: Re: Hall Effect for Over-current shutdown? Thread-Index: AQHONIVwPgZTz0IejkqHWI0PQfyJJ5jMrEmT///hroCAACyVug== Date: Mon, 8 Apr 2013 20:12:54 +0000 Message-ID: <7E7DFBB4D102A04DB5ADC88D66628A4A0FB994BD@ICTS-S-MBX5.luna.kuleuven.be> References: , In-Reply-To: Accept-Language: nl-BE, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.112.13.11] MIME-Version: 1.0 X-HELO-Warning: Remote host 134.58.240.130 (rhcavuit02.kulnet.kuleuven.be) used invalid HELO/EHLO cavuit02.kulnet.kuleuven.be - verification failed X-Spam-Score: -3.1 (---) 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: Hello Warren, that should be possible, I have used a A1302 Hall sensor as a "no contact" >100A current monitor. The sensor was just some mm away from the wire and was calibrated once using a (expensive) amp. meter. [...] Content analysis details: (-3.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [134.58.240.130 listed in list.dnswl.org] -2.4 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 91e1efbff209cbddb14bc9e018c2cfe8 Subject: RE: LF: Re: Hall Effect for Over-current shutdown? Content-Type: multipart/alternative; boundary="_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FB994BDICTSSMBX5lunaku_" 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,TO_ADDRESS_EQ_REAL 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-sid: 3039ac1d618a51632517537e X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FB994BDICTSSMBX5lunaku_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello Warren, that should be possible, I have used a A1302 Hall sensor as a "no contact" = >100A current monitor. The sensor was just some mm away from the wire and was calibrated once usin= g a (expensive) amp. meter. At lower currents it might be better to let the wire run a small loop with = the sensor inside. The output voltage is proportional to the magnetic field (=3D current throu= gh 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). So a= t 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 us= ing a 30V supply. The G0MRF uses a current sense resistor to shut down the amp quickly in cas= e too much current is being draw. I've modified the output transformer turns ratio to produce more power at l= ower 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-si= nked. 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 a= mplifier 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-cu= rrent because a high voltage has welded/melted a short between drain and so= urce, then the protection wont help ....high currents usually lead to exces= s heating ......but what is the real cause? If you really need DC supply pr= otection would not a high-side current monitor be easier/faster??? The prob= lem 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 FET= s 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 --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FB994BDICTSSMBX5lunaku_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hello Warren,

 

that should&= nbsp;be possible, I have used a A1302= Hall sensor as a "no contact" >100A curren= t monitor.

The sensor was just some mm&nbs= p;away from the wire and was calibrated=  once using a (expensive) amp.= meter.

At lower currents it might be better to let the wire<= a> run a small loop with the sensor inside.

The output voltage is proportional to the&n= bsp;magnetic field (=3D current through wire= ) with a offset voltage of 2.5V (at 5V<= a> supply voltage).

Just be sure to get= a linear Hall sensor (not the latch type) a= nd be aware that most Hall sensors are&= nbsp;rather slow (some 10..100us response time). = So at 136kHz it will resond t= o the average current rather than = peak currents.

 

73, Rik  ON7YD - OR7T

 

 

Van: owner-rsgb_lf_group@blacksheep.org [o= wner-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 config= uration, 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 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 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 protect MOS= FET 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 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 befor= e, or even if, you can disconnect the supply.
 
OK drive fails permanently on might be a conditio= n it would protect the FETs against with DC coupled drive
 
Alan G3NYK
----- Original Message -----
Sent: Monday, April 08, 2013 7:15 PM=
Subject: LF: Hall Effect for Over-cu= rrent 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

 
--_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FB994BDICTSSMBX5lunaku_--