---- START NEW MESSAGE --- Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-8.05) id A0F4437B007A; Thu, 29 Jan 2004 16:10:28 -0800 Received: from PEAR.EASE.LSOFT.COM (209.119.0.19) by cherry.ease.lsoft.com (LSMTP for Digital Unix v1.1b) with SMTP id <20.00CC3957@cherry.ease.lsoft.com>; Thu, 29 Jan 2004 18:40:15 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8e) with spool id 5104 for PICLIST@MITVMA.MIT.EDU; Thu, 29 Jan 2004 18:40:08 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 8284; Thu, 29 Jan 2004 18:39:02 -0500 Received: from linda-1.paradise.net.nz [202.0.58.20] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with ESMTP ; Thu, 29 Jan 2004 18:39:02 EST X-Comment: mitvma.mit.edu: Mail was sent by linda-1.paradise.net.nz Received: from smtp-3.paradise.net.nz (smtp-3a.paradise.net.nz [202.0.32.196]) by linda-1.paradise.net.nz (Paradise.net.nz) with ESMTP id <0HS900L1MZ135B@linda-1.paradise.net.nz> for PICLIST@MITVMA.MIT.EDU; Fri, 30 Jan 2004 12:39:03 +1300 (NZDT) Received: from Paradise (202-0-40-99.adsl.paradise.net.nz [202.0.40.99]) by smtp-3.paradise.net.nz (Postfix) with SMTP id 18A94AE0A4 for ; Fri, 30 Jan 2004 12:39:03 +1300 (NZDT) MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-Mailer: Microsoft Outlook Express 6.00.2800.1158 Content-type: text/plain; charset=windows-1255 Content-transfer-encoding: 7bit X-Priority: 3 X-MSMail-priority: Normal References: Message-ID: <00f301c3e6c1$30265140$7b01a8c0@Paradise> Date: Fri, 30 Jan 2004 12:37:25 +1300 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: Russell McMahon Subject: Re: [EE]: DIAC question To: PICLIST@MITVMA.MIT.EDU Precedence: list X-RCPT-TO: Status: U X-UIDL: 371856375 > I need a 10v diac for a circuit I want to test and cant get one. > can I use 2 reverse zeners in parallel as a diac? Only maybe. Two zeners will conduct at the target voltage BUT will reduce the applied voltage by the zener voltage plus about 0.8 volts. A DIAC will "break down" when it's conduction voltage is reached and drop a much smaller voltage across it when it is "on". If your circuit responds as desired to the voltage 'left over" when the zeners conduct then they will work for you. If however the circuit was depending on the sudden surge of current which occurred when the DIAC turned on then zeners will not provide the desired result. You can build a DIAC equivalent from a number of parts ( eg transistor(s), diodes, zener) Russell McMahon -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. .