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Re: Topband: Detuning Relay Flyback Diode

To: <topband@contesting.com>, "Brian Pease" <bpease2@myfairpoint.net>
Subject: Re: Topband: Detuning Relay Flyback Diode
From: David Cutter via Topband <topband@contesting.com>
Reply-to: David Cutter <d.cutter@ntlworld.com>
Date: Sun, 24 Dec 2017 19:15:28 -0000
List-post: <mailto:topband@contesting.com>
From a relay hold-on point of view, this will perform very similarly to the diode across the relay.

David
G3UNA


----- Original Message ----- From: "Brian Pease" <bpease2@myfairpoint.net>
To: <topband@contesting.com>
Sent: Sunday, December 24, 2017 5:18 PM
Subject: Re: Topband: Detuning Relay Flyback Diode


I am sure that some rigs use an "open drain" MOSFET instead of a "normal" transistor. The built-in "body diode" of the MOSFET acts as a built-in snubber for the reverse polarity transient, and should easily handle the current.

On 12/24/2017 11:49 AM, Paul Christensen wrote:
A single-component option with the benefits of the combo diode/Zener that Jim described is a “Transorb” device. The link below opens an application note that discusses various forms of coil transient suppression, beginning with passive, then single diode, a combo diode-Zener (mentioned by Jim and recommended by Schrack) and then concludes with the “Transil,” ST’s trade name for their transorb device.

https://tinyurl.com/ydyy8pqt

Paul, W9AC

Sent from my iPhone8
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