Go to eBay or Google, search on 12 to 6 volt DC step down converter. Since a horn is basically a short circuit (low resistance) get one with a higher amperage rating. Say 3 to 6 amps. Since a horn is used only for very short durations, the electrical power is dissipated in the converter quickly and not burn it out. Follow the connection instructions and you should be good to go. Good luck on your project.
Dave W
email (option): dwdiak4@gmail com
Cheers Dave
I'll give it a go.
Dean
No problem. I did the opposite on my M20 for an upgrade to 12V LED headlamp bulbs and tail lamp bulb for improved visibility. 6V stepped up to 12V DC, 3 amp rating. Only 1/2 amp draw when all LED lights are on as opposed to about 4 amps with the old incandescent bulbs. An additional 1/2 amp draw for the coil ignition system. Does not even register on the ammeter when I turn on the lights. I can see better and others can see me better. I don't care much about originality when it comes to improved safety and reliability.
Regards
Dave W.
email (option): dwdiak4@gmail.com
Hi Dean,
recently I repaired my Lucas Horn and measured a current of 3 Amps while using 6 V power. http://tdvma.blogspot.nl/2017/09/how-not-to-disassemble-lucas-horn.html
so use the famous Ohms Law V =I x R ( volt= Current x Resistance) to calculate a the value of the resistor in series of your 6 Volt Horn
yo need a 6 Volt voltage drop while a current of 3 amps goes trough the horn (and the series resistor .
this give 6/3= 2 ohms.
the 2 volts resistor will dissipate 6 volts and 3 amps this ends up in 6x3 = 18 watts. (Watts= Volt x Current)
so a resistor of 2 ohms and 18 watts in series of the horn will do fine. most resistors are 2.2 ohm that are available.
Also you can use 2 resistors of 3.9 ohm (each 10 watt) in parallel . 3.9/2 gives 1.85 oms that can handle 20 (2x10) watts
an example is e.g. https://www.conrad.nl/nl/widap-160121-draadweerstand-22-in-behuizing-100-w-1-stuks-1525263.html
regards
Ruud
email (option): ruud.klaui@gmail.com
So Dave, you stepped up the voltage for the LED's, so I assume that it's also possible to step up the voltage and use a 12v Altette? I too consider electrics to be a black art!
I know that Taff the Horn sells kits to convert 12v Altette's to 6v - but advises strongly against doing this unless you're pretty competent in this department.
I would far prefer to use a 12v hooter rather than require it. I picked up a box of 12v items once, so rather than butcher them I'd rather use them if I can in their original state.
Bruce
Not sure if I understand your question. However, if the Q is to use a 6V DC battery and charging system system to drive a 12V DC horn, the answer is yes. Using a 6 to 12V step up converter. As long as you don't exceed the amperage of the converter for very long and risk burning it out. As a precaution, use the highest amperage converter (within reason) you can get, like 10 amps. Here are examples of high amp DC converters for negative ground:
https://www.amazon.com/DIGITEN-Converter-Regulator-Waterproof-Module/dp/B019GY2FLW/ref=sr_1_2/134-1823396-0744455?ie=UTF8&qid=1508422389&sr=8-2&keywords=6+volt+to+12+volt+converter
https://www.amazon.com/KNACRO-Converter-Regulator-Waterproof-Module/dp/B073GHM3QW/ref=sr_1_13/134-1823396-0744455?ie=UTF8&qid=1508422389&sr=8-13&keywords=6+volt+to+12+volt+converter
I don't necessarily recommend either of these, just using what I quickly found on the internet as examples of what to look for. Make sure you wire the converter according to the supplier's instructions.
Just make sure you get one with the proper ground polarity, either negative or positive. If you are not sure, inspect the battery post connections on your vehicle. The battery posts are marked (-) negative and (+) positive. Trace the wires leading from the posts and see where they go. The one that terminates to the bike frame and/or engine is the ground lead. If you are unsure, get someone to help you. That way you don't risk buying the wrong converter and burning it out, or rendering it inoperative. Also, on my M20, I use a common negative ground (the bike frame) for both the 6 and 12 volt wiring. It works without any problems for a year now. I originally thought to run separate ground loops for the 6 and 12 volt wiring, but it was proved unnecessary. Saves on running extra wires for separate ground loops.
The usual converter issue is: the larger the current rating, the larger the converter, and the more difficult it is to mount / hide on a motorcycle. Also the larger the unit, usually higher cost.
Good luck on your project
Dave W.
email (option): dwdiak4@gmail.com
Ruud
many thanks for the very helpful information.
I have already ordered a step down converter as suggested by Dave but I think I'll get some resistors and also try it that way as a mini-project (I must get out more!)
Hi Dean,
interesting subject isn't it ?
yesterday I got the idea of using two 6 volt batteries in series, you can charge them with a 12 volt regulator , and for the horn you use only one battery of 6v .
I have been in electronics more than 45 years and the problem is always the mechanical packaging ... The electronic function is not the problem, but the challenge is always to get it mechanical well installed and mounted. ( so a resistor is a crime to mount it on a bike)
2 x 6 volt batteries must fit into a dummy battery box..again a challenge.
I liked the idea of using the step up converter . By just using this one for the LED lamps which are widely available for 12 volt use. Benefit of the step up converter is that the voltage can drop down and the output stays the same . for LED lamps this is very important since decreasing voltage will result in a significant light output drop down.
another benefit is one can use the original 6 Volt dynamo unfortunately with the bad 6 volt regulators of Lucas. ( these are unreliable devices and so they destroy either your battery or/and the dynamo...)
I started long time ago on my matchless and triumph's to install a 12 volt battery with LED lamps. I "disconnect" the dynamo by removing the chain on the matchless ( terrible adjustment chain). Since the Alette Horn didn't work I have solved the 12 volt issue. So I charge from time to time the battery with a external charger.
and the TRW triumph I mounted a Triumph trident 12 volt horn that worked after it had been in parts for more than 30 years...
on my latest 3HW project I have to check if the dynamo works ( I am not going to spend a fortune in rewiring the rotor) , if not we go for 12 Volt battery and LED only solution without horn...
ruud
email (option): ruud.klaui@gmail.com
I run 12 volt electrics on my WM20. Have two 4.5 amp gel batteries fitted into old battery casing but still retain a 6 volt clear hooters horn been this way for 8+ years no problem.Also use 55/60w H4 headlamp bulb I can now see where I am going at night..
2 cyclone 6v batteries will fit in a dummy case and can be connected for 12v if required. They seem to hold a charge for ages when the bike is laid up.