Return-Path: Received: from [65.33.160.45] (account ) by logan.com (CommuniGate Pro WebUser 4.1b6) with HTTP id 2343520 for lml@lancaironline.net; Sun, 11 May 2003 08:16:15 -0400 From: "Marvin Kaye" Subject: Re: voltage regulators To: lml X-Mailer: CommuniGate Pro WebUser Interface v.4.1b6 Date: Sun, 11 May 2003 08:16:15 -0400 Message-ID: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit Posted for "Gary Casey" : <<1) Use a linear regulator in you airplane. Older voltage regulators modulate the field current in the alternator by periodically connecting it to the full buss voltage. The average voltage from the alternator is "regulated" but the ripple voltage is large and must be absorbed by the battery.>> While I agree that a "linear" regulator is preferable, I don't agree with the reason. A normal regulator pulse-width-modulates the field current and while the voltage to the field is chopped, the current in the field is nearly constant because of the high inductance of the field and the "free-wheeling" diode in the driver. I think you'll find the characteristic of the alternator output is essentially identical. The advantage of the linear regulator as sold by B&C is that there is less Electromagnetic Interference (EMI) caused by the regulator. That difference may or may not be enough to justify the linear regulator, depending on the susceptibility of the rest of the system. Gary Casey ES #157