61 A10 electrickery

[Chrisf1]

Hi again everyone my dynamo has died so when I have it rebuilt I am thinking of going 12v the only problem is my newly fitted 6v altette horn is there a way round this? Thanks Chris

[admin]

I came across this interesting site 'LUCAS ALTETTE ORIGINALS ONLY'
http://www.taffthehorns.com/

Looks like they supply parts for 12v conversion, or maybe do a swap ?

e

[Chrisf1]

Unfortunately mine is not an original just exspensive repro Chris

[Triton Thrasher]

It won't matter, for all the time you have the button pressed.

[rocket man]

another idea put a 12 volt horn someware you carnt see it like under the tank
you could use the bar which goes across drill a hole in the centre  and mount your horn on it
and disconect the 6 volt horn no one will knowe were the sound is coming from
only you 

[Beezageezauk]

Hi Chris.

I was going to convert one of my 6v bikes to 12v a few years ago and the instructions I was given didn't even mention the horn.  When I enquired about it the reply was as Triton Thrasher states.  It shouldn't matter putting 12v through your 6v horn for the amount of time you will have the horn button pressed.  I would tend to agree with the statement but I am sure that some electrical wizard on the forum will be able to advise if this is true.   

I didn't carry out the conversion in the end so my bike is still running on 6v.

Beezageezauk.

[dpaddock]

Place a resistor in series with the horn having the same value of resistance as the horn and a wattage value equal to 144 divided by the resistance.

David

[trevinoz]

David, where does the 144 come from? If you divide 144 by the horn resistance, typically 0.6 ohm, you will need a huge resistor or bank of resistors.
The horn should be happy with 12V, it may need to be adjusted but I don't know how it is done on the repros as I haven't had the pleasure of playing with one yet.
I would ensure my horn wiring was up to scratch to handle the extra current.
Trev.

[BSA_54A10]

I used a resistor from an old ignition coil as I have a box load of old car coils.
Seems to work so for but then the only time I use the horn is to get a roadworthy or at a static display for some fun.

I also know a few upgraded bikes that have the original 6V hornl sans resistor.
Seems to work OK.
Remember that you should only be using it for very short burst so as long as you don't ride like an Italian (hand perminently on the horn) it should be ok as is although the note is horrible.

[Chrisf1]

Hello again everyone after discussing this with Tony Cooper who in my opinion is the best for electrical rebuilds (mags or dynamo's) he has convinced me to stay with 6v so I apologise for wasting your time but it has been nice talking thanks Chris

[a10gf]

Agree, with a good working system, a good battery and one of those nice halogen in front, 6v is fine. But it was an interesting discussion, always nice to read the opinions and ideas. And found this fascinating Altette specialist site in the process.
e

[beezalex]

As thrasher said, a 6V horn works just fine with a 12V system.

[dpaddock]

Trev, the point I was trying to make is that when you double the voltage, you increase the power dissipated by four. Chrisf1 is concerned that his new 6v horn might be damaged by going to 12 volts. I got sideways with the math but if Chris wants to protect his horn, he'll need to put an equal resistance in series with it; if it's a 0.6 ohm horn, the power rating of the resistor should also be equal and that calculates to 60 watts.
Without that resistor, the horn's going to draw 20 amps and dissipate 240 watts. I believe it's capable of that for short bursts, but "short" is a relative term.
David