[Fot] A type OD

[Bill Babcock]

Nice advice, you could also do it with a big capacitor, but you might  
stumble upon a tuned circuit and be jamming radio stations every time  
you shifted.
On Mar 9, 2008, at 12:10 PM, Gary Schneider wrote:

> A waterproof switch and insulated terminals are a good plan for  
> reliability but won't fix the problem. The switch body needs to be  
> grounded by a separate wire back to the trans or chassis. The lack  
> of a ground means your body becomes the ground path and that is what  
> causes the shock. The moisture provides a leakage path from the  
> switch terminals to your wet hand. The shift lever is not a good  
> ground, as the grease around its base is an insulator.
>
> When the OD switch opens, the solenoid generates a large negative  
> voltage as its magnetic field collapses, same principle as your  
> ignition coil. 12V won't give you a shock but that will. The best  
> solution is a power diode from the solenoid terminal to ground to  
> suppress the kickback voltage entirely. That's standard practice in  
> electronic circuits since the kickback is destructive of electronic  
> controls and switch contacts. The striped cathode side goes to the  
> solenoid terminal, other side to ground. The diode conducts when the  
> negative voltage occurs and harmlessly shunts out the kickback. It  
> could be mounted right on your switch after the ground wire is added.
>
> Example Radio Shack part http://www.radioshack.com/product/index.jsp?productId=2062579
>
> Regards,
> Gary Schneider
>
> ----- Original Message ----
> From: Rob <19to1tr6 at comcast.net>
> To: Friends of Triumph <fot at autox.team.net>
> Sent: Saturday, March 8, 2008 2:33:31 PM
> Subject: [Fot] A type OD
>
> With all the rain in Boston today it reminds me of a problem I need  
> to correct
>
> My OD switch is mounted to a welded tab  on the gear shift lever In  
> a rain
> race with soaking wet gloves,suit and shoes I was getting a pretty  
> good shock
> each time i activated the OD
>
> The switch  has open poles and is not water proof
>
> Will a water proof switch and insulated mounting correct this Or  
> will i have
> other wiring considerations. thanks    rob
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Bill Babcock
Babcock & Jenkins
Billb at bnj.com
503.936.7660
www.bnj.com