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Author Topic: switch  (Read 1616 times)

cassf1

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switch
« on: August 17, 2009, 08:37:04 PM »

hi

I want to use a switch in boat. I have a sub miniature from maplin rated
   
 2A AC 250V 
 5A AC 125V 
 5A DC 30V

Would this be OK to use with 12v battery and 25a ESC with 20a fuse, would the fuse blow before switch?
Would i wire battery then fuse then switch, also hoping to put a phono jack in for charging with this switch off  would it be OK to just connect up from poz and neg from battery
switch is just on/off
If this switch is no good could someone give me link for one toggle waterproof cover as will be out deck
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malcolmfrary

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Re: switch
« Reply #1 on: August 17, 2009, 09:29:23 PM »

Depends entirely on the load.  If the load is more than 5A, the switch will have a short life.  Probably more due to the arc generated when switching off, but there is likely to be an issue with heating due to carrying current above the rating.  Have a look at auto auxiliary light switches.  On the plus side, they are usually of adequate current rating.  The downside is that they generally need a very firm, strong mount.
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OMK

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Re: switch
« Reply #2 on: August 17, 2009, 09:44:58 PM »

I had the exact same question as you many moons ago.
apparently, your 2A 250vac switch is good for 4 amps if you half the voltage to 125vac... good for 8 amps at 60vac... good for 16A at 30vac... and so on.
Of course, we're talking AC here - not DC. But, for the most part, pretty much stands good for model boaters' and their DC supplies anyway.
Depends on how many amps your system is pulling. As Malcomlfrary sez, 5A 30V sounds a bit puny.

Maplin might be able to help you with the waterproof covers. You could also try technobots.co.uk



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Colin Bishop

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Re: switch
« Reply #3 on: August 17, 2009, 10:09:28 PM »

But presumably when you switch on or off no current will be flowing if the motors are stopped so arcing should neot be an issue. All the switch is doing is making the circuit live and carrying the maximum load current.

Colin
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FullLeatherJacket

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Re: switch
« Reply #4 on: August 17, 2009, 10:33:34 PM »

http://www.action-electronics.co.uk/stuff2.php

Third picture down; 16A toggle switch. Belt and braces. Fit under a hatch.

The switch you have is OK for a Rx supply or lighting circuit.

Admiral Bish is right, up to a point - that point being where the current melts the switch contacts.

Suit yourself.

FLJ
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wombat

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Re: switch
« Reply #5 on: August 21, 2009, 06:48:45 PM »

Hi Caasf1,

Well I am going to be a bit boring here but hey-ho

The switch you have is probably a bit underrated - but you should get away with it as long as the normal running current of the motor is around 5A. The typical ratings for a switch are for switching under load - so the current rating takes into account inrush currents which can be 10 to 20 times the operating current. You can get away with a higher current if you switch off load (i.e. with the motors not running). Saying that, you should rate the switch and the fuse pretty closely - 20A with a 5A switch is too much of a difference. Rate the fuse based on the current draw of the motor - rate the fuse as close as you can to the maximum normal current draw - if you get nuisance blowing of the fuse move up a size. Rate the switch according to the fuse. Be aware though, that switches are often designed and rated on the assumption that there will be a current inrush - they are designed to spark which is used to burn off contamination and get a good contact - without that you can get problems with contact resistance.

Wom


hi

I want to use a switch in boat. I have a sub miniature from maplin rated
   
 2A AC 250V 
 5A AC 125V 
 5A DC 30V

Would this be OK to use with 12v battery and 25a ESC with 20a fuse, would the fuse blow before switch?
Would i wire battery then fuse then switch, also hoping to put a phono jack in for charging with this switch off  would it be OK to just connect up from poz and neg from battery
switch is just on/off
If this switch is no good could someone give me link for one toggle waterproof cover as will be out deck
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cassf1

  • Guest
Re: switch
« Reply #6 on: August 22, 2009, 11:46:42 PM »

Thanks for the replies everyone have found a switch 16a and cover only thing is its dpdt and I'm not sure how to wire this.
on/off/on
Would like to wire this so that
on run
off
on charge
Know how to do this if there 3 tabs, tab 1 motor tab 2 battery tab 3 charger socket
Can anyone help please
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OMK

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Re: switch
« Reply #7 on: August 23, 2009, 03:14:36 AM »

Your DPDT switch will have six contacts. I'm guessing that yours is of the rocker-type, whereas the sketch illustrates a slide-type switch. Don't let that bother you (for the most part the contacts will be the same anyway).
All you need to do is connect the battery to the center two contacts. Each pair of outer contacts go to your ESC and recharge socket respectively.


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cassf1

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Re: switch
« Reply #8 on: August 23, 2009, 02:54:25 PM »

Thanks PMK mine will be toggle switch and that was just what i was hoping for even i cant go wrong
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