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Coil replacement

wdariusw

Nov 10, 2014
149
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Nov 10, 2014
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149
Hi all. I have a headache.. o_O I need to find replacement for car transponder coil... Original coil have about 920uH inductance and about 30 Ohm resistance. There are "replacements" from aliexpress (http://www.aliexpress.com/item/10-p....q90jxt&ws_ab_test=201407_5,201444_6,201409_4) , but when i have bought it, replacement coil have 2.65mH inductance and about 300 Ohm resistance. Transponder do not work with that replacement. There are also one capacitor in paralel without wich transponder do not work with original coil. It is possible to make transponder work with different ( 2.65mH instead 920uH) inductor and parralel capacitor combination than original ? Thanks !
 

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wdariusw

Nov 10, 2014
149
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Nov 10, 2014
Messages
149
I'm trying to fix my another renault laguna key card with broken coil.
 

wdariusw

Nov 10, 2014
149
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Nov 10, 2014
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149
You do not understand. I want to solder other coil, but THERE ARE NO EXACT REPLACEMENT.
 

Martaine2005

May 12, 2015
4,932
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May 12, 2015
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4,932
Hi,
I think Colin is saying to open the coil in the key fob that is not working.
It may be broken at the pin connection.
You may even be able to re-solder it there.

Martin
 

Colin Mitchell

Aug 31, 2014
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Aug 31, 2014
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You cannot buy the component. It is called a "HOUSE'" component and its value may be very critical. It could be 100kHz or higher transfer.
You have to do as I say.
I have not fixed 35,000 electronic devices because I am stupid.
 

AnalogKid

Jun 10, 2015
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Jun 10, 2015
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The economics of large-volume manufacturing are working against you. While it can cost thousands of dollars to have a manufacturer create a custom or modified-standard version of something as simple as an inductor, the custom part might reduce the overall cost of the circuit, and saving only a few cents per assembly can add up to tens of thousands of dollars in savings over a multi-year production run. Because of this, the odds that you will find a drop-in replacement part off the shelf are virtually zero. Try looking for a used device on ebay and scavenge what you need from it.

ak
 

Nanoamps

Feb 14, 2011
6
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Feb 14, 2011
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6
Not sure how you know what the correct inductance value is supposed to be, but its not all that difficult to wind your own inductors / coils. There is much information on the web to that. One might need a method of testing your home-built coil to see that its final value is close to your intended spec.
 

Colin Mitchell

Aug 31, 2014
1,416
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Aug 31, 2014
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Inductance is only one attribute to a coil.
I have an outdoor solar light with two coils (inductors) 0.47mH. One is 4R9 the other is 10R. They cannot be swapped over.
Inductance means nothing.
The wire size and ferrite core may also have an effect. It is much quicker to pull the coil apart and find the ends of the wire.
 

Nanoamps

Feb 14, 2011
6
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Feb 14, 2011
Messages
6
Agreed that coils aren't defined by a single attribute. I think your advice to try to ressurect the existing part is sound repair advice. The poster apparently believes he/she has damaged the part beyond repair.
There's a few million engineers, however, that wil be quite surprised by your newly defined law where inductance is irrelevant. Not to mention all those R/F circuits that now have to quit working.
 
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