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Author Topic: fuse  (Read 4995 times)

tomo55

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fuse
« on: April 15, 2009, 09:23:24 AM »

Where does the fuse go is it on the positive lead between battery and speed control?
Thanks all
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tomo55

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Re: fuse
« Reply #1 on: April 15, 2009, 09:30:05 AM »

re above found info I needed on another thread ,as a further point what is the general opinion of using a switch and a fuse or using a inline fuse and removing it when not running?
saw on the other thread that there was a difference of opinion?
thanks again Chris
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Shipmate60

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Re: fuse
« Reply #2 on: April 15, 2009, 09:37:53 AM »

I use car type blade fuses as the contact area is good for its size.
Do NOT use the in line plastic holder as the limiting factor is not the fuse, but the current capacity of the SPRING.

Bob
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stallspeed

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Re: fuse
« Reply #3 on: April 15, 2009, 10:06:37 AM »

The steel spring is supposed to be threaded over cable to push the brass contact against the fuse.

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malcolmfrary

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Re: fuse
« Reply #4 on: April 15, 2009, 11:41:44 AM »

Whether the current goes via the spring or not, the real current limiter is the heat generated by the poor contact pressure generated by the said spring.  Avoid the in-line tubular types for anything more than a couple of amps, and use the blade type.
Use of a switch becomes a matter of choice and convenience to fit.
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Shipmate60

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Re: fuse
« Reply #5 on: April 15, 2009, 12:33:09 PM »

Stallspeed,
Some of the cheap ones use the spring as a conductor.
But even so as malcolmfrary has said they are only good for small currents.

Bob
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andrewh

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Re: fuse
« Reply #6 on: April 15, 2009, 12:48:56 PM »

Chris,

All that people say about fuses is good stuff - just bear in mind what will happen when the fuse does what its name implies - fuses!

It will cut out that bit of the circuit - it is generally a good idea to make sure that you still have a rudder that works, and perhaps one of the motors still live :}

I would endorse using the car blade fuses - they are good enough for electric flight, and you can get nifty fuse-holders from car accessory shops which avoid the need to crimp on terminals.

FWIW I believe that Action Electronics make little fuse boards - sometimes combined with other useful equipment - it might be worth studying their website since FLJ takes the trouble to clearly draw the circuits, etc.

andrew

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DickyD

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Re: fuse
« Reply #7 on: April 15, 2009, 01:50:18 PM »

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stallspeed

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Re: fuse
« Reply #8 on: April 15, 2009, 03:10:03 PM »

Stallspeed,
Some of the cheap ones use the spring as a conductor.
But even so as malcolmfrary has said they are only good for small currents.

Bob
Yes,I have come across those in cigar socket connectors for sat-navs and stuff....low current.
I've come across nylon,or maybe acetal,holders where the fuse heat has melted the contact into the holder.

When using folded leaf contacts in Tamiya connectors or flimsy fuseholders or switches with ball connections  you have to consider Power =I2x Resistance when running at 20 amps.

To answer the original question    place the fuse in the positive power line. The fuse will pop on reverse polarity connecton with most fully electronic controllers.
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jonny shoreboy

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Re: fuse
« Reply #9 on: April 15, 2009, 08:06:56 PM »

Hi everyone, I have a silly fuse question which fits with this topic, so I hope people don't mind me asking it here as opposed to starting a new thread...

My question is if I am going to add a fuse on my lead from the battery to the ESC, where exactly do I put it? By that I mean, I have a battery with a tymia type connector, which is the same as the ESC, so I figured I would put the fuse between the battery and the connector?

The same question goes for the fuse between the motor and the positive of the ESC, I figured I would add it in between the motor and the ESC plugs?

The other other question is, if I have all these breaks on the lines will this effect performance of the whole circuit?
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FullLeatherJacket

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Re: fuse
« Reply #10 on: April 15, 2009, 08:08:29 PM »

The fuse will pop on reverse polarity connection.

What sort of fuse is this, and where can I buy a million of them?

FLJ
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craftysod

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Re: fuse
« Reply #11 on: April 15, 2009, 08:47:57 PM »

Jonny
stick the fuse between the motor an esc,if the prop gets caught up in something,and overloads motor,fuse will blow before esc
Mark
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DickyD

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Re: fuse
« Reply #12 on: April 15, 2009, 09:08:15 PM »

The fuse will pop on reverse polarity connection.

What sort of fuse is this, and where can I buy a million of them?

FLJ
Really hate to say this Dave, but he's right, both myself and Bob (shipmate60 ) have experienced this.  :embarrassed:
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stallspeed

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Re: fuse
« Reply #13 on: April 15, 2009, 10:29:11 PM »

The fuse will pop on reverse polarity connecton with most fully electronic controllers.
AberdeenAngus too.
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FullLeatherJacket

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Re: fuse
« Reply #14 on: April 16, 2009, 08:22:39 AM »

Really hate to say this Dave, but he's right, both myself and Bob (shipmate60 ) have experienced this.  :embarrassed:

Perhaps if I'd asked Martin to move the subject to "Jokes and Humour" before I made my last posting then it would have been a little clearer to all as to my reasons for making it. It's been a trying week - largely caused by folk who refuse to read instruction manuals or display even one iota of common sense - and I needed a little levity. Examples:

Cust#1: It says I have to adjust the pot while the power is off
FLJ: That's right
C: How do I know whether the power is off?
FLJ: You move the slider of the power switch to the end opposite the one which is marked "On". I know it sounds absurd, but try it anyway - it might just  work.

Cust#2: Can you send me a drawing of where the VR pots are?
FLJ: They're on the drawing which you already have, marked with the legends VR1, VR2, VR3 and VR4. We technocrats call it 'a clue'.

Perhaps I'll add a few smileys to highlight my attempts at humour in future.

As for "Aberdeen Angus", what is   he on?

O, yes - almost forgot. The answer to tommo55's question is YES!

FLJ
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John W E

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Re: fuse
« Reply #15 on: April 16, 2009, 10:03:42 AM »

hi there one and all

FLJ has made light of the statement of putting a fuse in the negative side of the supply.  For those who have no electrical knowledge whatsoever, a little insight might help one understand.

When we look at electrical circuits, we naturally think that the voltage plus current flows from the positive to the negative - or the red to the black wire - in actual fact it is the reverse.  Also, inside the majority of electrical speed controllers/switchers/sound modules etc., the electrical 'track' on the back of the circuit board in places is thinner than fuse wire.

So, if one has a direct short or one reverses the polarity of the supply, one is going to get a 'weak-spot' and that weak-spot is going to be the thinnest part of the board which is going to burn out and not the fuse.

One of the reasons for this happening, is, inside the circuits there are components such as diodes which (for the non-electrical minded) work like a 1-way gate - where it only allows electricity to go 1 way but, it doesn't allow electricity to come back.

There are also things called electrolytic capacitors which again, or the non-electrical minded, they are similar to a battery which store up electric and then discharge it at a given time and these only work in a particular way.

So....can you see where we are going here - these components are all fitted into a circuit in a certain way - so that they will all allow current to pass through in one direction.  Not the opposite direction - so, if we connect our battery up the wrong way round - they are not going to function as they should, thus blocking the flow of electricity/current and therefore causing a build up and 'busting' the weakest point on your circuit board being either - the thin track of the circuit board or a very fragile other component such as a transistor or an IC (integrated circuit).   

over and out  - keep it simple

aye
john e
bluebird
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stallspeed

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Re: fuse
« Reply #16 on: April 16, 2009, 10:15:18 AM »

I hate the present set of smilies too.
Here is another freebie design to protect circuits when the battery polarity is reversed:-
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DickyD

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Re: fuse
« Reply #17 on: April 16, 2009, 11:39:39 AM »

Great, so what is it o great one ?
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stallspeed

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Re: fuse
« Reply #18 on: April 16, 2009, 02:25:29 PM »

Did somebody call me?

It's one of these www.mtroniks.net/details1.asp/ProductID/283/RVP70.htm without the red and green light.
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FullLeatherJacket

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Re: fuse
« Reply #19 on: April 16, 2009, 04:26:32 PM »

Thirty quid, eh? Bargain! Nice  mark-up (if you can get it).
 
Me? I'd rather save the money and just spend a couple of minutes checking my connections before putting a battery in circuit. That's why we pragmatists down here at the bottom of the techno-pond favour polarised plugs and sockets, and why we tend to colour-code our wiring. But hey - it's a big world and a broad church, isn't it?

Just remember to connect your new RVP the right way around to the speed controller before you try it out, and you'll never blow a 10p fuse again.

Now - about those polarity-sensitive auto blade fuses  %)

FLJ

(Just to add that any tendency towards humour detected in this posting is entirely without coincidence)
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Peterm

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Re: fuse
« Reply #20 on: April 16, 2009, 06:29:21 PM »

FLJ,  Its easy, my old friend, just turn the fuse around.   Pete
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wombat

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Re: fuse
« Reply #21 on: April 16, 2009, 09:22:07 PM »

Hi Chris,

Fuse - as an absolute minimum, a fuse should be placed between the battery and the ESC. Rate the fuse at around 2/3 the rating of the ESC. If you have space, I pprefer to have a fuse on the input of the motor (output of the ESC) to protect the ESC in case the motor stalls, then a fuse (larger rating than the first) between the ESC and the battery - this protects the boat from turning itself into a funeral pyre if there is a fault in the ESC. Better to place the fuse as close to the battery as possible to protect aganist wiring faults.
Conventionally the fuse goes in the positive line for a negative earth system. On a model boat, probably does not make a great deal of odds, though it is helpful to stick to convention especially if you have to call on others to help

I would suggest including a switch rather than pulling the fuse - fuse holders and plugs/sockets are designed for a relatively limited number of insertion/removal cycles. Switches are designed for more cycles and will give reliable operation over a longer period.

Reverse polarity connectors - don't bother with them, just do the wiring properly - they just waste energy. They are designed for muppets that cannot be ar**d to do the job properly and check before switching on.

Wom
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DickyD

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Re: fuse
« Reply #22 on: April 16, 2009, 09:29:32 PM »

Thats a bit rich, a bloke called Wombat calling me a muppet. ok2
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John W E

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Re: fuse
« Reply #23 on: April 17, 2009, 10:19:42 AM »

Dicky I wouldn't regard it as an insult being called a mup by the Wom - when ya take into consideration - if everyone on this Forum pooled their electronics knowledge together - the Wom forgets that amount of knowledge when he blinks his eyes.   He is a sheer genius - I havent met him yet, but I have seen some of his electrical work.

Anyway I live with Miss Piggy!  :embarrassed: :D

aye
John e
bluebird
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DickyD

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Re: fuse
« Reply #24 on: April 17, 2009, 10:32:48 AM »

Remind me to have a word with your other half John  %)
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