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Author Topic: Lack of sleep (Fuse or not to fuse?)  (Read 9327 times)

Colin Bishop

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #50 on: August 27, 2008, 08:56:19 PM »

No need to apologise. It's been an interesting excursion but having read all the pros and cons I'll just stick with the standard fuses on the main battrey and motors as I've always done.

Colin
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #51 on: August 30, 2008, 06:30:12 AM »

Well Dicky you were so right what a load of twaddle that guy posts I think it is a sad case of you will listen to what i say and do as I am right all the time,funny thing is we have not seen one of his installations or even a boat!!!!!!!!!!!!!!!!!!!!!!!



Stavros

Stavros,
 you asked to see one of my installations.

I'm heavily influenced by three leading British installation artists. I've incorporated elements of all three.
decomposing fruit by Sam Taylor-Wood
the upstairs room by chris ofili                ( 3 1/2 lbs of elephant dung)
my bed by tracy emin                           (the kid's and not mine)

I found some real twaddle too. "rewinding dc motors" in http://www.modelboatmayhem.co.uk/forum/index.php?topic=10984.0
Regards
Barry Park
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Proteus

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #52 on: August 30, 2008, 09:25:30 AM »

wow is that a DEMON speed controler in the middle, I still have a couple and even one with the extra TURBO..


Proteus
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #53 on: August 30, 2008, 09:36:20 AM »

Banana
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John W E

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #54 on: August 30, 2008, 09:47:07 AM »

Ah, this proves this man has a wicked sense of humour; I LIKE IT  {-) {-)

I can see a couple of 'ancient' Electronize speed controllers there, and, possibly one or two Maplins' so it proves he has been or is a Member of Time Team and been on an archaeological dig  O0 {-) {-)

All we need to do now is extract his information in a clear and easy format - so that those with little knowledge of electronics can gain unwaffled knowledge  :D :D ::) ;D {-) {-)

aye
john e
bluebird
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OMK

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #55 on: August 30, 2008, 09:49:02 AM »

More goodies than you can shake a stick at, but nope - definitely a banana SKIN.
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #56 on: August 30, 2008, 09:55:12 AM »

It's black now!
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John W E

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #57 on: August 30, 2008, 10:00:15 AM »

Must be 3 days old and on the 27MHZ band that  banana {-)
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #58 on: August 30, 2008, 10:03:31 AM »

I'm trying to make a serious point!
You can avoid all that if you use a fuse.

......and also remove the cover of Electronize ESC's.

Heat build up melts the relay plastic & shorts out the relay.
They can be fixed if a fuse blows but not after 100 Amps  fries the pcboard.

Barry Park
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wombat

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #59 on: August 30, 2008, 10:11:19 AM »

Hey Wombat,  more info please!

For those old codgers who use braces ,but no belt, here's my definition of your "string"

A big shunt diode will protect an ESC , in conjunction with a fuse ,where the person is COLOURBLIND i.e. prone to connect the battery the wrong way round.
A reverse-polarity induced fault current is likely to destroy fully electronic (non-2-pole relay ESC's ) on 12 volts even when a fuse is present.
An alternative is a low resistance FET transistor to block reverse voltage altogether.

My semi fuse ref was only because Martin said he heard polymer PTCC's were faster than fuses (I think thats what he meant)
Like you, I know (i squared t) and have used up a few sheets of log graph paper too! :)


What more information, Barry, you sure like to get your thrupence worth. 

Liked the installation - though the banana was perhaps gilding the lily (unlike my more normal practice which seems to be more akin to polishing a 'xxxxx')

I have a reluctance to put in series diodes to protect the user from connecting the unit up incorrectly as they suck up power. A parallel diode when used as a flywheel protection device is fine. I have had to do this on one case because the the built in flywheel diodes in the FETs weren't up to the job when used with some rather hot motors. The thinking on the three fuse system was this:

1/. Main line fuse - last ditch protection when all else fails to prevent the possibility of fire
2/. Fuses on each motor line to protect the ESC in the event of a motor jam - I would suggest this even if the ESC has protection itself after seeing a few protected ESCs let out the magic smoke given that encapsulated ESCs do not have a smoke reinstallation valve.
3/. Fuses on the input to each ESC - really only needed in a multiple motor application - if one of the ESCs goes PHUT, this fuse should fail leaving the rest of the system operational allowing you to limp back to the shore.

Polyfuses -  I suspect the characteristics will be similar to Varistors - I use those for mopping up the energy from lightning strikes along with spark-gaps and transient diodes - on the higher current ones the thermal mass could make the characteristic a bit soggy on marginal overloads . My preference is still for something that gives you a clear indication of a problem. Polyfuses ISTM are for applications where overload is to be expected (for instance finger trap protection on car winders or surge protection on a telecomms line) rather than where it is a sign of an abnormality on the the system.

Wom

The Prat-in-the-hat's trivia
Banana error - one of the classic programming errors - when you fail to terminate a loop correctly. From the little girl who stated "I know how to spell banananana, I just don't know when to stop"
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #60 on: August 30, 2008, 10:17:03 AM »

Sorry Wom, but I skip long posts and I advise anyone to do likewise.
1 Do you recognise the 3 1/2 lb tome? You have the switchgear one I bet! (fuses )
2 You and Malcolm missed the deliberate mistake on the "anti-shuffle" circuits
3 What is all this c..p about increasing motor torque by rewinding?  Seriously!

Barry Park
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #61 on: August 30, 2008, 10:21:55 AM »

What more information, Barry, you sure like to get your thrupence worth. 

Liked the installation - though the banana was perhaps gilding the lily (unlike my more normal practice which seems to be more akin to polishing a 'xxxxx')

I have a reluctance to put in series diodes to protect the user from connecting the unit up incorrectly as they suck up power. A parallel diode when used as a flywheel protection device is fine. I have had to do this on one case because the the built in flywheel diodes in the FETs weren't up to the job when used with some rather hot motors. The thinking on the three fuse system was this:

1/. Main line fuse - last ditch protection when all else fails to prevent the possibility of fire
2/. Fuses on each motor line to protect the ESC in the event of a motor jam - I would suggest this even if the ESC has protection itself after seeing a few protected ESCs let out the magic smoke given that encapsulated ESCs do not have a smoke reinstallation valve.
3/. Fuses on the input to each ESC - really only needed in a multiple motor application - if one of the ESCs goes PHUT, this fuse should fail leaving the rest of the system operational allowing you to limp back to the shore.

Polyfuses -  I suspect the characteristics will be similar to Varistors - I use those for mopping up the energy from lightning strikes along with spark-gaps and transient diodes - on the higher current ones the thermal mass could make the characteristic a bit soggy on marginal overloads . My preference is still for something that gives you a clear indication of a problem. Polyfuses ISTM are for applications where overload is to be expected (for instance finger trap protection on car winders or surge protection on a telecomms line) rather than where it is a sign of an abnormality on the the system.

Wom

The Prat-in-the-hat's trivia
Banana error - one of the classic programming errors - when you fail to terminate a loop correctly. From the little girl who stated "I know how to spell banananana, I just don't know when to stop"
Right!
Read your post as far as line 4
shunt diode.....What series diode are you on about?
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #62 on: August 30, 2008, 10:26:24 AM »

Wom, I've just finished reading that and I now understand what they were all on about!
I've now rejoined huminity.
You might be out of date on "Polyfuses"

Barry Park
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #63 on: August 30, 2008, 10:34:48 AM »

OK,see what you mean now.
 There is no diode forward voltage drop on the "anti-shuffle" The transistor is enhanced and about .01 ohm if the battery is connected right.
The mistake is on the P-fet version,by the way.

Barry Park
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OMK

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #64 on: August 30, 2008, 10:43:22 AM »

Oh, I geddit now!........

The 3.5lb tome is there to denote your loathing of long posts (not your own long post - just those from other members), and the banana could signify someone either slippery or cowardly, and all those broken gadgets are to show your affinity with rubbish.

The floozy I'm with this weekend, she just said: "I much prefered his old signature... skin as tough as a rhino' ass."
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DickyD

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #65 on: August 30, 2008, 10:50:46 AM »

Does this bloke not know when to stop, or have we got to put up with this twaddle clogging up the postings for ever.

What do you reckon PMK ?
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wombat

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #66 on: August 30, 2008, 11:02:36 AM »

Hi Barry

OK I will keep this short in deference to your limited attention span  :P

Don't recognise the tome...."Power Electronics Handbook" - but whose, couldn't quite make out the publisher. The book of reference for my generation was Lander - came with a pink cover. Surprisingly, don't have a handy tome on switchgear but since part of the company designs the stuff, there is no substitute for a bit of face-time.

Anti-shuffle circuit - didn't really look at it if truth be told.

Hey don't get me started on motor torque and model boats - if it can spin the prop in a bucket of water it has got enough torque AFAIC.

Polyfuses - have to admit my use of them is limited - they still fall into a gap for my (professional) applications - really need a higher voltage rating in most cases and a higher energy rating. A self resetting fuse is no good if you end up picking bits of it out of your teeth each time it is triggered. Also looking at some of the higher voltage ones they are pretty slow responding - time to trip on a 10* overload on the ones I looked at are of the order of 1 second. I note that the smaller ones do not specify a trip time - biggest disincentive for me though is the thermal derating curve - over the expected temperature range the trip current varies by 30% from the nominal.

If it is still too long just drop every other word.

Wom
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #67 on: August 30, 2008, 11:10:45 AM »

Wom, I didn't read that one either.
PMK,
You see the problem in ping-pong emails and message boards ? {-)
Nobody has a clue what anyone is on about!

I've got to go now! But I'm posting a question in Electrics and all things and I'll see how sharp or completely random the answers are.
There were no posts in this section for 24 hours. Did you notice?
Who scared everyone away? :embarrassed:
Come back! I love to read all these crazy but helpful tips like "got a metal to metal joint somewhere?"  It's payback for the hours learning a craft repairing tight fisted old pensioners' write-offs.
There must be 100+ commonly occuring R/C faults so diagnosis requires logical deduction and eliminating half known issues at a time.

Barry Park
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malcolmfrary

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #68 on: August 30, 2008, 11:24:48 AM »

Quote
2 You and Malcolm missed the deliberate mistake on the "anti-shuffle" circuits
3 What is all this c..p about increasing motor torque by rewinding?  Seriously!
I learnt on valves, the instructors were struggling with the new-fangled fad of transistors, so what I did pick up was all about bipolar types, silicon transistors were a thing of wonder, and FETs happened after I had moved on.  Humorous FET drawings therefore pass me by.  Sorry.
Taking all the wire out of a motor and replacing it with a similar volume of different thickness wire will alter the motor characteristics.  Easy for those practised in the art, potential disaster for those who aren't.  The curly wire part of C&G co-incided with finding out about booze, bikes and birds.  No contest.
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