The Ford Barn

Drbrown · 04-03-2016, 06:19 PM

My 6v horn relay was not working and prior owner changed system to 12v. Put in a '56 Ford 12v relay and have changed the 6v horns to work in-series to accommodate the 12v change. Each horn is mounted on a vertical metal strut that comes up thru the belly pan in front of the radiator. Those struts provide each horn with separate electrical ground connections.

Horns were made by Sparton and castings are imprinted "LO" (right side) and "HI" (left side). Main body is die-cast metal and dome covers stamped-steel. The die-cast body did not rust and mild surface rust on and inside the domes cleaned-up nicely.

Substituted the metal strut under the left horn with a matching home-made polyester piece (88 cents at Walley), eliminating its elec ground connection. Then connecting that horn to the right hand horn lets them operate in series. Although the voltage thru the circuit is dropped, I notice that the loudness of the right hand horn seems comparatively less .... no big thing .... one can switch the "HI" and "LO" pitched horns if desired.

Oddly, the horn trumpet opening faces upward. I thought that was an invitation to water damage but any water that leaked in was able to drain out an opening in the bottom of the assembly leaving limited damage. The manufacturer provided a durable design and brass nuts on all parts. (here come the playful comments)

koates · 04-03-2016, 06:58 PM

Horns cant work connected in series, have to be in parallel. Either run them on 12 volts for a louder and rough out of tune sound or with a resistor in series with each horn to drop the supply voltage to 6 volts for the correct in tune sound. Regards, Kevin.

Charlie Stephens · 04-03-2016, 07:18 PM

Quote:

Originally Posted by koates

Horns cant work connected in series, have to be in parallel. Either run them on 12 volts for a louder and rough out of tune sound or with a resistor in series with each horn to drop the supply voltage to 6 volts for the correct in tune sound. Regards, Kevin.

I may be wrong here but I assumed you could run two 6 volt horns in series with a 12 volt system. Each horn would see 6 volts across it assuming that they both had the same resistance. What am I missing? Of course the first horn would need to be isolated from ground so the current would flow through it to the second horn (and not to ground as normally encountered).

Charlie Stephens

ford38v8 · 04-03-2016, 07:20 PM

Kevin, Drbrown wasn't asking if it would work, he was telling how he made it work.

Kinda looks like the key to invention is to not have advance knowledge that it won't work.

Fordestes · 04-03-2016, 07:36 PM

I connected two 6volt horns to 12 volts in series by mounting on a wood insulator, had one a little louder so I switched positions and was so loud every neighbor on the block looked out their front door to se where the freight train was coming through, Had one hell of a shock when I touched the wires to the battery. I didn't use a relay I had just purchased them from a swapmeet and was testing them.I only had a 12 volt battery.

Fordestes · 04-03-2016, 07:39 PM

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when I use the horns I an going to ask some electrical guru what resistor I will need to connect them the correct way and drop them to 6volts.

19Fordy · 04-03-2016, 09:31 PM

When converting to 12V I used a 60 ohm resistor to make my stock 40 Ford BATT gauge operate on 6 volts. This may help.
https://www.fordbarn.com/forum/showth...rting+12+volts

flatheadmurre · 04-03-2016, 10:29 PM

The horn are a switch operated at a specific frequency so connecting 2 with different frquencys in series will not be working very good.
You get lower output and frequency cause they will "misfire" when one is open and the other doesn´t get any current.
Operating them at 12v for a short period will probably not burn them up but you get a higher pitch from them.
So a dropping resistor as stated above is the correct way.

fordor41 · 04-03-2016, 10:35 PM

I connected my trumpet style '41 horns in parallel and ran them on 12V for years. Of course I didn't blow them for extended periods of time. Finally burned one out when I hit a large pothole in Ohio and the relay stuck. Thought they were going to blow the paint off the hood before I could get them disconnected!

Drbrown · 04-03-2016, 11:22 PM

Quote:

Originally Posted by koates

Horns cant work connected in series, have to be in parallel. Either run them on 12 volts for a louder and rough out of tune sound or with a resistor in series with each horn to drop the supply voltage to 6 volts for the correct in tune sound. Regards, Kevin.

The horns DO work when connected in series. At least mine do. To add .... my horn circuit is on a 30 amp fuse. A member in the forums tested his 6v horn circuit and found it didn't draw more than 20 amps. If the relay or horns malfunction and draw more current the fuse will blow.

Drbrown · 04-03-2016, 11:27 PM

Quote:

Originally Posted by Fordestes

I connected two 6volt horns to 12 volts in series by mounting on a wood insulator, had one a little louder so I switched positions and was so loud every neighbor on the block looked out their front door to se where the freight train was coming through, Had one hell of a shock when I touched the wires to the battery. I didn't use a relay I had just purchased them from a swapmeet and was testing them.I only had a 12 volt battery.

That's why a relay is used. Too much draw at initial connection i.e. like connecting a large motor. Relays help prevent "arching" at the connection point when heavy loads are connected.

Drbrown · 04-04-2016, 12:11 AM

Quote:

Originally Posted by 19Fordy

When converting to 12V I used a 60 ohm resistor to make my stock 40 Ford BATT gauge operate on 6 volts. This may help.
https://www.fordbarn.com/forum/showth...rting+12+volts

Reducing voltage for gauges is generally different. However regarding horns there is a 2015 thread on Ford V8 which recommends a 0.5 ohm 50 watt resistor on the feeder if that's the way one wants to go.

Drbrown · 04-04-2016, 12:27 AM

Quote:

Originally Posted by fordor41

I connected my trumpet style '41 horns in parallel and ran them on 12V for years. Of course I didn't blow them for extended periods of time. Finally burned one out when I hit a large pothole in Ohio and the relay stuck. Thought they were going to blow the paint off the hood before I could get them disconnected!

This I don't understand .... ? ? .... if the points in the horn, which are normally in closed position, "burned-out" it wouldn't work. But if the relay "burned-out" another words fused in its connected position, then the horns would sound continuously as described.

It was not uncommon in-the-old-days for a horn relay to freeze or malfunction, and the driver or mechanic would dash under the hood to pull the wires apart.

Flat Ernie · 04-04-2016, 08:39 AM

You can run the horns in series if one is electrically isolated. They will not be as loud as they could be. This is because they make/break each other's circuit, but it does help to keep the current down a little - start-up current will still be high though.

It is far easier to run them in parallel as original and have them be louder. If you still have a 6V horn relay, they are often better than 12V replacements because the contacts are often heavier. But I've found that aftermarket relays are better still.

The horns, which already draw high current, particularly on start-up, will draw double that on 12V.

I really like to find and use the 48-52 F1 dual trumpet horns - man are they loud on 12V. But most trumpet horns will be nice and loud. The other thing I like about the earlier horns is most are adjustable and the contacts can be cleaned. Pull the bell off the back and you can dress the points, replace any frayed wires, and adjust the tone/sound/volume.

Flat Ernie · 04-04-2016, 08:54 AM

Quote:

Originally Posted by 19Fordy

When converting to 12V I used a 60 ohm resistor to make my stock 40 Ford BATT gauge operate on 6 volts. This may help.
https://www.fordbarn.com/forum/showth...rting+12+volts

The 60 ohm resistor for the BATT gauge is a calibration issue. Although the BATT gauge acts as a voltmeter, it is still measuring current. Consequently, it's important to know the resistance of the entire circuit - in this case, the Ford service manual gave us the 60 Ohm value, so we double it to keep the current through the gauge the same (most voltmeters are really measuring current, just calibrated to show voltage).

Quote:

Originally Posted by Drbrown

Reducing voltage for gauges is generally different. However regarding horns there is a 2015 thread on Ford V8 which recommends a 0.5 ohm 50 watt resistor on the feeder if that's the way one wants to go.

Finding a high wattage, low ohm resistor is likely a challenge, but it might work - would need to know the impedance of the horns to say if that was the correct value or not. It's likely very close though, just by gut feeling...

flatheadmurre · 04-04-2016, 09:37 AM

How about a dropping resistor for an ignition coil ?
Is in the right range and should probably survive normal use...

Drbrown · 04-04-2016, 10:48 AM

Quote:

Originally Posted by flatheadmurre

How about a dropping resistor for an ignition coil ?
Is in the right range and should probably survive normal use...

In my case that's an interesting question. Seem to remember that those OE coil resistors only drop the voltage from abt 6v to 3 or 4 volts - but I could be wrong. My OE Circuit Breaker with its 6v coil resistor are unused (my coil was changed-out for a 12v coil with internal resistor). I can run some jumper wires and see what my meter reports. I'd either need to go back to a 6v relay or put the resistor on the horn-side of the 12v relay. However, that OE is an open-air resistor and probably not suitable exposed in an engine compartment.

Flat Ernie: www.digikey.com/products-search .... an on-line company that offers wide range of resistor sizes and types, as well as other electronic items at reasonable prices and shipping for small orders. They sell a "Dale #RW-50 50watt 0.5 ohm which is encased/mountable abt 2 inches long.

flatheadmurre · 04-04-2016, 12:20 PM

I was more thinking about the modern ceramic square ones usually around 0.5ohm.
The voltage drop is depending on the current going through the resistor so one dropping 3v in one aplication can drop 1v in another.

Flat Ernie · 04-04-2016, 05:43 PM

I'd just run 'em on straight 12V. They're nice and angry sounding.

fordor41 · 04-04-2016, 10:36 PM

Quote:

Originally Posted by Drbrown

This I don't understand .... ? ? .... if the points in the horn, which are normally in closed position, "burned-out" it wouldn't work. But if the relay "burned-out" another words fused in its connected position, then the horns would sound continuously as described.

It was not uncommon in-the-old-days for a horn relay to freeze or malfunction, and the driver or mechanic would dash under the hood to pull the wires apart.

When I hit the pot hole the horns started to blow. I disconnected them at the relay but one horn was no good after that. I used the other horn for about 10 yrs after that happened.

koates · 04-04-2016, 10:39 PM

Quote:

Originally Posted by ford38v8

Kevin, Drbrown wasn't asking if it would work, he was telling how he made it work.

Kinda looks like the key to invention is to not have advance knowledge that it won't work.

I will try to re answer this question. Two horns connected in series will work to varing degrees, but not in tune as originally designed by the OEM. The internal components of each horn have a coil winding and a set of contacts in series with the coil winding. Connect another horn in series with the first horn and you then have two sets of contacts opening and closing at a rapid rate and interfering with the current flowing in both horn coils. This does not make for an efficient operating set of horns. As I stated earlier a parallel connection is the CORRECT way to connect horn sets so that they do not interfere with each other. I guess that some people are happy enough that the horns just make some sort of noise. Macs and others do supply resistors capable of operating 6 volt horns on 12 volts. Other cases do arise where 6 volt electrical items can be connected in series to work well on 12 volts. These items are usually bulbs or electric motors etc which have a constant current draw. To ford38v8 s little statement about advance knowledge, yes a do have a little bit of that, about 55 years in the auto electrical trade !!! Regards, Kevin.

Graeme / New Zealand · 04-05-2016, 12:55 AM

My 48 is running the 46 trumpet style earlier horns on the inner fender under the hood ( because I like them). On one of them the guts was stuffed so I took the guts out of a 48 "snail" type horn I had lying around and got them both to work. I presume the electrical parts are interchangable as they looked the same. I presume it is not the electrical componant (the guts) but the length of the trumpet or twists in the "snail" type that detemines the note. Both mine are similar in note when I sound the horn although the horns are of two different lengths and they are both working. If I stuff a piece of cloth in the longer horn I get a beautiful definate 2 tone note that sounds better. Would i be able to adjust the contacts to get a better sound without the use of the rag?

GB

flatheadmurre · 04-05-2016, 01:34 AM

You adjust the points gap to set the frequency in a horn.
Longer gap will take more time to travel and give lower note.
Then theres a design limit on every horn...

koates · 04-05-2016, 05:14 AM

The tone of a horn is determined by several design features. As noted the length of the trumpet can have an effect on the tone. Take for instance horns that are marked "H" and "L" for high and low but look exactly the same as each other on the outside and the inside workings as well. Whats the difference here ? As an example 1933 to 1935 ford deluxe cars are like this, both exactly the same looking horns except for the thickness or gauge of the metal diaphragm which nobody usually checks. For correct operation and tone horns have to be wired in parallel. Regards, Kevin.

flatheadmurre · 04-05-2016, 05:45 AM

The difference in weight of the moving part or strenght of the diapragm acting as a return spring set the tone to.

rotorwrench · 04-05-2016, 08:31 AM

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A horn coil works as an electromagnet but it also works as a resistor for a component that might be connected in series with it. The first one connected in the series will be getting most of the current. The last in the series will be less so the current draw will never have a balance between the two. Using dropping resistors with horn connections in parallel would work better. At least there would be a tone balance if both are in similar condition.

I always loved the sound of a good working pair of OEM 6-volt horns. Nothin made now days does a good job of replicating that. Truly a blast from the past.

Flat Ernie · 04-05-2016, 09:02 AM

Quote:

Originally Posted by rotorwrench

A horn coil The first one connected in the series will be getting most of the current. The last in the series will be less so the current draw will never have a balance between the two.

That's simply not accurate.

The reason the second horn doesn't sound right is as koates described above. The contacts in each horn interfere with current flow through each other.

rotorwrench · 04-05-2016, 05:52 PM

I agree that the first vibrator coil making and breaking the circuit interferes with the current to the next & vice versa but there is a little more going on there in a series circuit. The statement is not totally inaccurate. There is more than one reason why one is louder than the other.

Flat Ernie · 04-05-2016, 08:42 PM

Quote:

Originally Posted by rotorwrench

I agree that the first vibrator coil making and breaking the circuit interferes with the current to the next & vice versa but there is a little more going on there in a series circuit. The statement is not totally inaccurate. There is more than one reason why one is louder than the other.

Whether you put the ammeter at the positive terminal, between the horns, or negative terminal, it will read the same - total current through the circuit will be the same regardless of where you measure it so long as the horns are wired in series.

The problem is, just as the second horn is getting its voltage, the first horn is opening its contacts, so it may not get enough TIME at full current to create a strong enough magnetic field to fully pull the contacts open. This is why it sounds weaker.

The voltage drop across the horns may be different if they have a different impedance/resistance in the coil, but the total current will be the same regardless of where you measure it.

Paul Bennett · 10-15-2016, 03:38 AM

Older electrical horns are non-linear electro-magnetic devices which are turned on by electricity then turn themselves off several hundred times a second. It's only actually on part time.

SERIES: Using one 6v horn to provide voltage for a second 6v horn requires the first horn to intermittently supply voltage to the second but the second must be on at the same time as the first to complete the electrical path. But the second also turns itself off cutting voltage to the first. This arrangement will make noise but not proper. When the first turns itself off the voltage is cut from the second. Since they are designed to operate at different frequencies, turning on/off at dissimilar times, there would be a sound. An odd sound indeed but it probably serve to scare little old ladies who accidentally venture into the street. Mounting anything on a piece of wood won't happen in my car, however.

Do what you will, but as an electrical engineer I say NO to series horns. Use readily available 12v horns available very cheap in junk yards. For new, consider the air variety which use a small air pump connected by hose to a trumpet. Their lower current draw and substantially less electrical noise to the radio and other audio devices make them quite attractive devices.

I have no clue as to peak current draw of the 6v horns soas to calculate a dropping resistor but I assure you the wattage would make them expensive (and large). One cannot use the average current unless a smoothing capacitor were also used. Just use a 12v horn for a cheap reliable component.

Paul Bennett · 10-16-2016, 05:09 AM

I just noticed that the 'EARLY FORD STORE' in San Dimas CA has a "Horn voltage reducer" for $28 ... pn A-13803. Specifically to reduce 12v for 6v horns. http://lbcunited.com/earlyford2/index.php/cPath/300

weemark · 10-16-2016, 05:23 AM

Quote:

Originally Posted by Paul Bennett

I just noticed that the 'EARLY FORD STORE' in San Dimas CA has a "Horn voltage reducer" for $28 ... pn A-13803. Specifically to reduce 12v for 6v horns. http://lbcunited.com/earlyford2/index.php/cPath/300

That's just a standard 12v - 6v reduced in an aluminium housing.

mrtexas · 10-16-2016, 08:24 AM

Quote:

Originally Posted by weemark

That's just a standard 12v - 6v reduced in an aluminium housing.

They work great. Marketed to Model A.

JSeery · 10-16-2016, 08:35 AM

Looks like a cool setup if it works.

flatheadmurre · 10-16-2016, 10:39 AM

It´s just a power resistor bolted to a heatsink no rocket science there.
You could probably bolt the resistor to the sheetmetal of the car and it will work as good.

JSeery · 10-16-2016, 11:07 AM

Didn't know anyone considered a resistor rocket science!

It's just a resistor of the correct value and wattage already mounted to a heatsink for the folks that have no idea how to calculate these things, nothing more.

drolston · 11-10-2016, 01:13 PM

A degree in electrical engineering proved to be of no help in the attempt to convert my '41 horns to 12 volts. Tried a range of high wattage resistors in series; tried a wound voltage tap resistor; tried a MSD DC/DC voltage reducer that worked on windshield wiper and heater motors. Nothing worked; mostly no sound. At the heart of the problem is the fact that you have an inductive coil that also presents a series resistance in a circuit that the make/break points cause to behave more like an alternating current circuit.

I just left mine on 12 volts. Sounds more like a freight train than a '41 Ford, but it gets the desired effect in traffic.

Someday I will get out the EE 201 text book and figure out what combination of resistor, capacitor and coil is needed to get the horns to behave as original.

rdmace1956 · 11-11-2016, 11:44 AM

I was thinking about the .3 to .6 ohm resistor to see how it works on the 41. Those big horns look so neat I want to try and keep them working. Was going to try them at 6v and try to measure the current draw just to make sure the resistor is reasonable. If the current flow is as high as I suspect, the usual 3 to 6 amp capacity dropping resistors in the catalogs probably will not be high enough resistance.

04-03-2016, 06:58 PM	#2
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,078	Re: Horns - 6 to 12 volt Horns cant work connected in series, have to be in parallel. Either run them on 12 volts for a louder and rough out of tune sound or with a resistor in series with each horn to drop the supply voltage to 6 volts for the correct in tune sound. Regards, Kevin.

04-03-2016, 07:20 PM	#4
ford38v8 Senior Member Join Date: Jul 2011 Location: SF Bay Area Posts: 6,634	Re: Horns - 6 to 12 volt Kevin, Drbrown wasn't asking if it would work, he was telling how he made it work. Kinda looks like the key to invention is to not have advance knowledge that it won't work. __________________ Alan

04-03-2016, 07:36 PM	#5
Fordestes Senior Member Join Date: May 2010 Posts: 886	Re: Horns - 6 to 12 volt I connected two 6volt horns to 12 volts in series by mounting on a wood insulator, had one a little louder so I switched positions and was so loud every neighbor on the block looked out their front door to se where the freight train was coming through, Had one hell of a shock when I touched the wires to the battery. I didn't use a relay I had just purchased them from a swapmeet and was testing them.I only had a 12 volt battery.

04-03-2016, 07:39 PM	#6
Fordestes Senior Member Join Date: May 2010 Posts: 886	Re: Horns - 6 to 12 volt Sponsored Links (Register now to hide all advertisements) when I use the horns I an going to ask some electrical guru what resistor I will need to connect them the correct way and drop them to 6volts.

04-03-2016, 09:31 PM	#7
19Fordy Senior Member Join Date: May 2010 Location: Coral Springs FL Posts: 10,921	Re: Horns - 6 to 12 volt When converting to 12V I used a 60 ohm resistor to make my stock 40 Ford BATT gauge operate on 6 volts. This may help. https://www.fordbarn.com/forum/showth...rting+12+volts

04-03-2016, 10:29 PM	#8
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Horns - 6 to 12 volt The horn are a switch operated at a specific frequency so connecting 2 with different frquencys in series will not be working very good. You get lower output and frequency cause they will "misfire" when one is open and the other doesn´t get any current. Operating them at 12v for a short period will probably not burn them up but you get a higher pitch from them. So a dropping resistor as stated above is the correct way.

04-03-2016, 10:35 PM	#9
fordor41 Senior Member Join Date: Oct 2011 Location: elmira,ny Posts: 1,516	Re: Horns - 6 to 12 volt I connected my trumpet style '41 horns in parallel and ran them on 12V for years. Of course I didn't blow them for extended periods of time. Finally burned one out when I hit a large pothole in Ohio and the relay stuck. Thought they were going to blow the paint off the hood before I could get them disconnected!

04-04-2016, 08:39 AM	#14
Flat Ernie Senior Member Join Date: May 2010 Location: 74FL Posts: 323	Re: Horns - 6 to 12 volt You can run the horns in series if one is electrically isolated. They will not be as loud as they could be. This is because they make/break each other's circuit, but it does help to keep the current down a little - start-up current will still be high though. It is far easier to run them in parallel as original and have them be louder. If you still have a 6V horn relay, they are often better than 12V replacements because the contacts are often heavier. But I've found that aftermarket relays are better still. The horns, which already draw high current, particularly on start-up, will draw double that on 12V. I really like to find and use the 48-52 F1 dual trumpet horns - man are they loud on 12V. But most trumpet horns will be nice and loud. The other thing I like about the earlier horns is most are adjustable and the contacts can be cleaned. Pull the bell off the back and you can dress the points, replace any frayed wires, and adjust the tone/sound/volume. __________________ Daddy always said, "If yer gonna be dumb, you gotta be tough" and I'm one tough sumbitch! T5 Tech

04-04-2016, 09:37 AM	#16
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Horns - 6 to 12 volt How about a dropping resistor for an ignition coil ? Is in the right range and should probably survive normal use...

04-04-2016, 12:20 PM	#18
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Horns - 6 to 12 volt I was more thinking about the modern ceramic square ones usually around 0.5ohm. The voltage drop is depending on the current going through the resistor so one dropping 3v in one aplication can drop 1v in another.

04-04-2016, 05:43 PM	#19
Flat Ernie Senior Member Join Date: May 2010 Location: 74FL Posts: 323	Re: Horns - 6 to 12 volt I'd just run 'em on straight 12V. They're nice and angry sounding. __________________ Daddy always said, "If yer gonna be dumb, you gotta be tough" and I'm one tough sumbitch! T5 Tech

04-05-2016, 12:55 AM	#22
Graeme / New Zealand Senior Member Join Date: May 2010 Location: Lower Hutt , New Zealand Posts: 2,126	Re: Horns - 6 to 12 volt My 48 is running the 46 trumpet style earlier horns on the inner fender under the hood ( because I like them). On one of them the guts was stuffed so I took the guts out of a 48 "snail" type horn I had lying around and got them both to work. I presume the electrical parts are interchangable as they looked the same. I presume it is not the electrical componant (the guts) but the length of the trumpet or twists in the "snail" type that detemines the note. Both mine are similar in note when I sound the horn although the horns are of two different lengths and they are both working. If I stuff a piece of cloth in the longer horn I get a beautiful definate 2 tone note that sounds better. Would i be able to adjust the contacts to get a better sound without the use of the rag? GB __________________ "you can't make honey out of dog sh*t" "You're a long time looking at the lid"

04-05-2016, 01:34 AM	#23
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Horns - 6 to 12 volt You adjust the points gap to set the frequency in a horn. Longer gap will take more time to travel and give lower note. Then theres a design limit on every horn...

04-05-2016, 05:14 AM	#24
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,078	Re: Horns - 6 to 12 volt The tone of a horn is determined by several design features. As noted the length of the trumpet can have an effect on the tone. Take for instance horns that are marked "H" and "L" for high and low but look exactly the same as each other on the outside and the inside workings as well. Whats the difference here ? As an example 1933 to 1935 ford deluxe cars are like this, both exactly the same looking horns except for the thickness or gauge of the metal diaphragm which nobody usually checks. For correct operation and tone horns have to be wired in parallel. Regards, Kevin.

04-05-2016, 05:45 AM	#25
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Horns - 6 to 12 volt The difference in weight of the moving part or strenght of the diapragm acting as a return spring set the tone to.

04-05-2016, 08:31 AM	#26
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,422	Re: Horns - 6 to 12 volt Sponsored Links (Register now to hide all advertisements) A horn coil works as an electromagnet but it also works as a resistor for a component that might be connected in series with it. The first one connected in the series will be getting most of the current. The last in the series will be less so the current draw will never have a balance between the two. Using dropping resistors with horn connections in parallel would work better. At least there would be a tone balance if both are in similar condition. I always loved the sound of a good working pair of OEM 6-volt horns. Nothin made now days does a good job of replicating that. Truly a blast from the past.

04-05-2016, 05:52 PM	#28
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,422	Re: Horns - 6 to 12 volt I agree that the first vibrator coil making and breaking the circuit interferes with the current to the next & vice versa but there is a little more going on there in a series circuit. The statement is not totally inaccurate. There is more than one reason why one is louder than the other.

10-15-2016, 03:38 AM	#30
Paul Bennett Senior Member Join Date: Sep 2016 Posts: 628	Re: Horns - 6 to 12 volt Older electrical horns are non-linear electro-magnetic devices which are turned on by electricity then turn themselves off several hundred times a second. It's only actually on part time. SERIES: Using one 6v horn to provide voltage for a second 6v horn requires the first horn to intermittently supply voltage to the second but the second must be on at the same time as the first to complete the electrical path. But the second also turns itself off cutting voltage to the first. This arrangement will make noise but not proper. When the first turns itself off the voltage is cut from the second. Since they are designed to operate at different frequencies, turning on/off at dissimilar times, there would be a sound. An odd sound indeed but it probably serve to scare little old ladies who accidentally venture into the street. Mounting anything on a piece of wood won't happen in my car, however. Do what you will, but as an electrical engineer I say NO to series horns. Use readily available 12v horns available very cheap in junk yards. For new, consider the air variety which use a small air pump connected by hose to a trumpet. Their lower current draw and substantially less electrical noise to the radio and other audio devices make them quite attractive devices. I have no clue as to peak current draw of the 6v horns soas to calculate a dropping resistor but I assure you the wattage would make them expensive (and large). One cannot use the average current unless a smoothing capacitor were also used. Just use a 12v horn for a cheap reliable component.

10-16-2016, 05:09 AM	#31
Paul Bennett Senior Member Join Date: Sep 2016 Posts: 628	Re: Horns - 6 to 12 volt I just noticed that the 'EARLY FORD STORE' in San Dimas CA has a "Horn voltage reducer" for $28 ... pn A-13803. Specifically to reduce 12v for 6v horns. http://lbcunited.com/earlyford2/index.php/cPath/300

10-16-2016, 10:39 AM	#35
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Horns - 6 to 12 volt It´s just a power resistor bolted to a heatsink no rocket science there. You could probably bolt the resistor to the sheetmetal of the car and it will work as good.

10-16-2016, 11:07 AM	#36
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Horns - 6 to 12 volt Didn't know anyone considered a resistor rocket science! It's just a resistor of the correct value and wattage already mounted to a heatsink for the folks that have no idea how to calculate these things, nothing more.

11-10-2016, 01:13 PM	#37
drolston Senior Member Join Date: Jun 2014 Location: Williamsburg, VA Posts: 1,627	Re: Horns - 6 to 12 volt A degree in electrical engineering proved to be of no help in the attempt to convert my '41 horns to 12 volts. Tried a range of high wattage resistors in series; tried a wound voltage tap resistor; tried a MSD DC/DC voltage reducer that worked on windshield wiper and heater motors. Nothing worked; mostly no sound. At the heart of the problem is the fact that you have an inductive coil that also presents a series resistance in a circuit that the make/break points cause to behave more like an alternating current circuit. I just left mine on 12 volts. Sounds more like a freight train than a '41 Ford, but it gets the desired effect in traffic. Someday I will get out the EE 201 text book and figure out what combination of resistor, capacitor and coil is needed to get the horns to behave as original.

11-11-2016, 11:44 AM	#38
rdmace1956 Member Join Date: Jun 2014 Location: Hope, Indiana Posts: 32	Re: Horns - 6 to 12 volt I was thinking about the .3 to .6 ohm resistor to see how it works on the 41. Those big horns look so neat I want to try and keep them working. Was going to try them at 6v and try to measure the current draw just to make sure the resistor is reasonable. If the current flow is as high as I suspect, the usual 3 to 6 amp capacity dropping resistors in the catalogs probably will not be high enough resistance.