Topband: Detuning Relay Flyback Diode

David Cutter d.cutter at
Sun Dec 24 14:15:28 EST 2017

>From a relay hold-on point of view, this will perform very similarly to the 
diode across the relay.


----- Original Message ----- 
From: "Brian Pease" <bpease2 at>
To: <topband at>
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 
> 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.
>> Paul, W9AC
>> Sent from my iPhone8
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