Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Tue, 11 Feb 2003 20:46:49 -0500 Message-ID: X-Original-Return-Path: Received: from [64.4.38.120] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.0.6) with ESMTP id 2021171 for flyrotary@lancaironline.net; Tue, 11 Feb 2003 19:00:53 -0500 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Tue, 11 Feb 2003 16:00:52 -0800 X-Originating-IP: [65.142.114.222] Reply-To: "Tracy Crook" From: "Tracy Crook" X-Original-To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Mazda Alternator Lamp circuit X-Original-Date: Tue, 11 Feb 2003 19:00:31 -0500 Organization: Real World Solutions Inc. MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Original-Message-ID: X-OriginalArrivalTime: 12 Feb 2003 00:00:52.0680 (UTC) FILETIME=[CEEB1480:01C2D229] ----- Original Message ----- From: "Ed Anderson" > I've been working with Tommy James on his alternator problem and the > question came up (it always comes up) - do we need the diode and relay shown > on the Mazda alternator wiring diagrams. It appears that if you are using > the Mazda alternator (mine is Bosch rebuild) then you do indeed need the > diode (and the relay if you want an lamp indicator) in the circuit going to > the "L" (Lamp?) terminal of the alternator. You certainly need the "L" > circuit to provide voltage to the alternator for the following reason. > > With the engine off, a current from the battery flows in the "L" circuit > closing the relay and thereby turning on the lamp (to indicate no charging > when the alternator is not running), and then throught the diode to the > alternators field coil (internally). This current provides the "initial" > starting current for the field coil of the alternator. Once the alternator > starts producing its own voltage then the regulator switches to using the > alternator's internally generated voltage for regulation. The "L" wire then > has essentially equal voltage on both sides of the diode which turns it > "off" stopping the current flow through it and the relay causing the "lamp" > to go out. > > For this reason, it is probably not wise to put a lamp directly in the "L" > circuit of the alternator (if it is one of the type described) because > should the lamp burn out or otherwise cause an open circuit, the alternator > field coil will apparently not get the initial starting current and will > fail to generate voltage. > Thanks to Tommy James for causing me to research this a bit more as I had > always wondered whether the "L" cirucit was needed if you didn't use the > "lamp" feature. It turns out it is on this alternator! > . > . > Ed Anderson > Matthews, NC > RV-6A N494BW > eanderson@carolina.rr.com I never investigated this either Ed. I mearly duplicated the circuit as used in the car in order to get it working. Tracy