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Relay question.
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Ray White



Joined: 02 Dec 2014
Posts: 6320
Location: Derby
PostPosted: Tue Jan 30, 2024 12:19 pm    Post subject: Relay question. Reply with quote
A little knowledge can be a dangerous thing, so as I only have a little knowledge of electrical things please may I ask a question here.

My 1949 MG TC is positive earth and I want to fit a relay to an electric fan that I have installed.

As I have electronics that need protecting from voltage spikes I have opted for a relay with diode protection.

I understand that unlike normal relays, a diode makes the relay polarity sensitive.

Have I wired this relay correctly? I am showing the positive earth at terminal 86. Is this correct or should the earth be connected to terminal 85?



Any help would be appreciated. Thankyou.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4105
Location: South Cheshire
PostPosted: Tue Jan 30, 2024 12:48 pm    Post subject: Reply with quote
No, that would introduce a short circuit when the fan is switched on, you need to reverse connections 85 & 86.

Dave
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Ray White



Joined: 02 Dec 2014
Posts: 6320
Location: Derby
PostPosted: Tue Jan 30, 2024 12:56 pm    Post subject: Reply with quote
ukdave2002 wrote:
No, that would introduce a short circuit when the fan is switched on, you need to reverse connections 85 & 86.

Dave


Many thanks, Dave.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4105
Location: South Cheshire
PostPosted: Tue Jan 30, 2024 1:18 pm    Post subject: Reply with quote
Sorry Ray

I'm talking rubbish, your circuit is correct for +ve earth!

Sorry
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Ray White



Joined: 02 Dec 2014
Posts: 6320
Location: Derby
PostPosted: Tue Jan 30, 2024 6:43 pm    Post subject: Reply with quote
ukdave2002 wrote:
Sorry Ray

I'm talking rubbish, your circuit is correct for +ve earth!

Sorry


No worries Dave.

The main thing is that I get it right in the end.

I am only trying to make the wiring as safe as I can.

There are so many stories of these cars going up in smoke Shocked .

.
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