Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 48D94380000A1; Mon, 8 Apr 2013 16:15:46 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UPI9x-0001Rg-4b for rs_out_1@blacksheep.org; Mon, 08 Apr 2013 20:55:21 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UPI9w-0001RX-8o for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 20:55:20 +0100 Received: from nm3-vm0.bt.bullet.mail.ird.yahoo.com ([212.82.108.88]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1UPI9q-0000uB-Pf for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 20:55:19 +0100 Received: from [212.82.108.230] by nm3.bt.bullet.mail.ird.yahoo.com with NNFMP; 08 Apr 2013 19:54:53 -0000 Received: from [217.146.189.77] by tm3.bt.bullet.mail.ird.yahoo.com with NNFMP; 08 Apr 2013 19:54:53 -0000 Received: from [127.0.0.1] by smtp827.mail.ird.yahoo.com with NNFMP; 08 Apr 2013 19:54:53 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=s1024; t=1365450893; bh=5Sr9hWxysVJFpmNCvLDGFH0C+XWZSzfoD3tSQHB5+hQ=; h=X-Yahoo-Newman-Id:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:X-Rocket-Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-Antivirus:X-Antivirus-Status; b=AxEWv8QHUQREGyyqffydt6/LJMHPFSz30tegsL7XXLqqM/8J0yGNiVXY+YO9p9obFOeFabZJgfgQ5greCHoU/fZ3mgbldBD/Z2kpJWyMP1ZOrEaDgG+RFzsvAl93vqG77hLqedpd/gOH2bfBTXvQfoupZxWUy906NZ70oevPzGA= X-Yahoo-Newman-Id: 514321.19701.bm@smtp827.mail.ird.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: r.BC8VYVM1l4En5PESmC6CdOuNJPxOKcuhID4cGSfefI5FQ iWpqUSai1GDbrJ_j595MhlQ0aAp0QxBrzkKULMLoRlS0dAOytxZjiyKrYsz5 S0lfECcDewA5aI3nLaLpbRLIOXmmhILKRya8MJ3Pbfa8i7mDhLvgdnTdmFK4 tcm7Drc5eySE8z_7wear2azOb8xl21VhctkqTeKeOYM3U9fbFwKZwmqAC5Su Jy.Vg800n69gSecD3C75TpkCm74hlqwuFHVGARMMtLMOlrNcJ7.ih9XpVHsv sQV4N6NoJ2RM5kd52h1mSAFJyISWltxVwou3tuGOg6ljm1716VfNFCuN.A_k IEu1YZKT0TcZP48bRPd939LlcD5QP9tQj4hBzemaD3iHduVFqeLnZjM02xdJ _VfA1O_a1KxkUAv1DlPuXm_n96TRPqzP32NPwcmS24zVUIJ5heKTYBNHBkYf dBuCaTBqQ4BU- X-Yahoo-SMTP: fpz.2VeswBBs59bVshRPmMN51lcO2lgFRIvE4XTqE8dRwOxd70E- X-Rocket-Received: from gnat (alan.melia@86.149.140.116 with login) by smtp827.mail.ird.yahoo.com with SMTP; 08 Apr 2013 12:54:53 -0700 PDT Message-ID: <7EB77D10460A4EBF9E1F63437A4C99A6@gnat> From: "Alan Melia" To: References: Date: Mon, 8 Apr 2013 20:39:27 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-Antivirus: avast! (VPS 130408-1, 08/04/2013), Outbound message X-Antivirus-Status: Clean X-Spam-Score: 0.0 (/) 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: Ah yes that is Class D and can go that way if mis-matched......that is a lot of power in a sensing resistor! I guess a Hall effect device or even a temp sensor would do that job. I think in over current condition a lot of power is dissipated in the devices. High side sensors should be available at 30v The sheets I have seen, suggest they require some assistance above about 40v. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.82.108.88 listed in list.dnswl.org] 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: bf14357d5ee2e4a717b88d90ab36122c Subject: Re: LF: Re: Hall Effect for Over-current shutdown? Content-Type: multipart/alternative; boundary="----=_NextPart_000_00CD_01CE3499.29807C50" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.5 required=5.0 tests=FORGED_MUA_OUTLOOK,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-da02.r1000.mx.aol.com ; domain : btinternet.com DKIM : pass x-aol-sid: 3039ac1d404a516325726af7 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_00CD_01CE3499.29807C50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ah yes that is Class D and can go that way if mis-matched......that is a = lot of power in a sensing resistor! I guess a Hall effect device or even = a temp sensor would do that job. I think in over current condition a lot = of power is dissipated in the devices. High side sensors should be = available at 30v The sheets I have seen, suggest they require some = assistance above about 40v. Alan ----- Original Message -----=20 From: Warren Ziegler=20 To: rsgb_lf_group=20 Sent: Monday, April 08, 2013 8:07 PM Subject: 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 -----=20 From: Warren Ziegler=20 To: rsgb_lf_group=20 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? --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 =20 --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 ------=_NextPart_000_00CD_01CE3499.29807C50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Ah yes that is Class D and can go that = way if=20 mis-matched......that is a lot of power in a sensing resistor! I guess a = Hall=20 effect device or even a temp sensor would do that job. I think in over = current=20 condition a lot of power is dissipated in the devices. High side sensors = should=20 be available at 30v The sheets I have seen, suggest they require = some=20 assistance above about 40v.
 
Alan
----- Original Message -----
From:=20 Warren = Ziegler=20
Sent: Monday, April 08, 2013 = 8:07=20 PM
Subject: Re: LF: Re: Hall = Effect for=20 Over-current shutdown?

Hi Alan,

    I've modified the G0MRF amp with the M0BMU output=20 configuration, I'm using a 30V supply.
The G0MRF uses a current sense resistor to shut down the amp = quickly in=20 case too much current is being draw.
I've modified the output transformer turns ratio to produce more = power at=20 lower supply voltages (I'm using 500V, 55a FETs).
However with the new higher currents and with a new appropriate = value=20 sense resistor its developing a LOT of heat (12 W or so) and needs to = be=20 heat-sinked.
I'm thinking Hall-effect might be more efficient and produce less = heat -=20 I'm pretty sure that others have used Hall effect devices to protect = MOSFET=20 amplifier and I'm looking for circuit tips.

73 & Tnx!
Warren




On Mon, Apr 8, 2013 at 2:52 PM, Alan Melia = <alan.melia@btinternet.com> wrote:
Ah interesting problem Warren.... why is it=20 over-current?? if it is over-current because a high voltage has=20 welded/melted a short between drain and source, then the = protection=20 wont help ....high currents usually lead to excess heating ......but = what is=20 the real cause? If you really need DC supply protection would not a=20 high-side current monitor be easier/faster??? The problem then could = be=20 there is enough energy stored in the PA choke to zap the FET before, = or even=20 if, you can disconnect the supply.
 
OK drive fails permanently on might be a = condition it=20 would protect the FETs against with DC coupled drive
 
Alan G3NYK
----- Original Message ----- =
From: = Warren=20 Ziegler
To: rsgb_lf_group=20
Sent: Monday, April 08, = 2013 7:15=20 PM
Subject: LF: Hall Effect = for=20 Over-current shutdown?

Anyone using a Hall effect device for overcurrent = sensing and=20 shutdown in a MOSFET amplifer?

--
73 Warren K2ORS
      =  =20         WD2XGJ
        =  =20       WD2XSH/23
        =  =20       WE2XEB/2
        =    =20     WE2XGR/1

 =20



--
73 Warren K2ORS
        =  =20       WD2XGJ
          =  =20     WD2XSH/23
            =  =20   WE2XEB/2
              =  =20 WE2XGR/1

 
------=_NextPart_000_00CD_01CE3499.29807C50--