Paul Kleiner Posted March 24 Share Posted March 24 I have a klaxon horn I believe is from a 6v system. When bench tested with a battery charger at 6v boost, it sounds terrific. However at 12v, it sounds a bit fast and loud. We installed it on my 2018 Jeep. With the car not started the horn sounds about normal, however, when car is running, and charging at 14v, it’s too much for the horn. We reduced voltage to 6v but now it is definitely sluggish…. Can anyone help me out with this issue please??? I have no idea the brand of horn or what it came from. It is something my grandfather had. Link to comment Share on other sites More sharing options...
Dave Mellor NJ Posted March 25 Share Posted March 25 They have resistors to knock 12 volts down to 6 voltsyou probably need to experiment to see what gets you to about 8 Link to comment Share on other sites More sharing options...
wayne sheldon Posted March 25 Share Posted March 25 Those resisters have a need for a certain amperage draw to effectively drop the voltage to the proper amount. The horn may be drawing too much current for the resister to drop the voltage to the proper six volts. The actual voltage drop may be taking it to five volts or even less. One size does not fit all. Been too long since I played with that stuff. Ignition amperage draw is much lower than what the horn wants. I might misremember the adjustment? I believe you would need a lower Ohm resister (if what you are using has an Ohm value listed on it?), but it still has to be able to handle the current demands of the horn or it will burn out quickly. Used to use ceramic resisters for higher current circuits. Zener diodes used to be common to help regulate circuit voltages, but I never used any that would handle the horn's demands. Link to comment Share on other sites More sharing options...
Fordy Posted March 25 Share Posted March 25 There are DC-DC converters around fairly cheaply from hobby electronics retailers. I would be trying one of those. Steve 1 Link to comment Share on other sites More sharing options...
Paul Kleiner Posted March 25 Author Share Posted March 25 I was thinking the same thing, if I could get the voltage to around 8-9 it would be just right. Unfortunately the step down converters I’ve played with don’t just knock the voltage down 3-4 volts, they solely limit to just 6 volts only Link to comment Share on other sites More sharing options...
Lee H Posted March 25 Share Posted March 25 If you have a multimeter that will read amperage, the next time you hook the horn up to your 6 volt charger, run it through the meter, and find out the amperage draw (and also find out the voltage the charger is putting out while the horn is operating, it won’t be exactly 6 volts). After that, it is a simple matter to apply ohms law to determine the exact resistor value you’ll need on 12 volts (and I’ll be glad to figure it for you, if you like). Link to comment Share on other sites More sharing options...
Bloo Posted March 25 Share Posted March 25 Yeah, that's not going to work well with a resistor. A klaxon is a DC motor, and DC motors make maximum torque and draw the most current when they are stalled. That means the horn has a much lower internal resistance when the motor is starting than when it is running. The resistance of any resistor you use will be more or less constant. There is no way to cut it back to a constant 6 volts with a resistor. It is electrically impossible. The voltages will divide according to the resistances, but the resistance of the motor goes up when it starts spinning. That means most of the voltage will be across the resistor when the motor is not turning. When the motor needs a bunch of power to start, its probably getting 2 volts or something and the resistor is getting the rest. You can't fool mother nature. The best you can do in a situation like that is choose a resistor with a low enough resistance to get enough voltage so that the motor starts good, and hope the motor does not burn up. As soon as the motor starts it will be running on quite a bit more voltage than it is designed for. Maybe it will work acceptably without burning up and maybe it won't. I don't know. The only good way to fix it would be to rewind the motor for 12 volts. Link to comment Share on other sites More sharing options...
AzBob Posted March 25 Share Posted March 25 As for running a klaxon on higher voltages, those who run their 6 volt Model A Ford Sparton horns on 12 volts makes them sound terrible. The sound is more of a higher pitched screech than a proper Ahooogahh. In my case, I experimented with a resistor and was disappointed with the results. In the end, I ended up buying a horn wound for 12 volts as per Bloo's suggestion. Link to comment Share on other sites More sharing options...
Paul Kleiner Posted March 25 Author Share Posted March 25 Thank you all for the insights, you’ve all been very helpful and informative. I’m going to do some more testing and decide the proper direction Link to comment Share on other sites More sharing options...
dodge28 Posted March 26 Share Posted March 26 You need to test the horn in the invarament condition it would normally work in the car. Hod the horn in a vise and use a 6 volt battery charged about 6 and as half volts. There are 2 terminals. It does not matter which wire, negative or positive , touch the terminals . The horn should blow, at least make some noise. There is a adjuster screw at the back. Turn this screw back and forth until the argoogah sound is loudest with little screech as possible. Most of these horns needs service at that age. Some years ago some outfit were reproducing them 12 volts, a sort of no name brand. They were sold by Canadian Tire. If you need it restored send it too Jason at EAR restorations. 1 Link to comment Share on other sites More sharing options...
Paul Kleiner Posted March 26 Author Share Posted March 26 Dodge 28… realizing the screw on the back is for sound adjustment was a huge difference. Horn sounded totally different between a bench test and mounted in the car. Adjustment is very sensitive as a sixteenth or eighth inch makes all the difference Link to comment Share on other sites More sharing options...
Paul Kleiner Posted March 26 Author Share Posted March 26 Link to comment Share on other sites More sharing options...
Terry Bond Posted March 26 Share Posted March 26 12 Volt horns are readily available. Check Evilbay. Terry Link to comment Share on other sites More sharing options...
Paul Kleiner Posted March 26 Author Share Posted March 26 Also do you have a website for EAR? When I search that I only got sites for ear surgery’s. Lol Link to comment Share on other sites More sharing options...
Paul Kleiner Posted March 26 Author Share Posted March 26 12v horns just don’t sound the same and this was my grandfathers. Link to comment Share on other sites More sharing options...
ABear Posted March 26 Share Posted March 26 12 minutes ago, Paul Kleiner said: 12v horns just don’t sound the same and this was my grandfathers. There are cost effective "buck/boost" converters that you can adjust the output voltage. These are modern "switching" power supplies and typically have a wide input and output voltage like the one in the link below which can take 6V DC-40V DC input and output 1.2V DC to 36V DC. The one in the link is good for up to 300W or around 20A.. $10 here https://www.amazon.com/dp/B0CSZ39XKV/ref=sspa_dk_hqp_detail_aax_0?psc=1&sp_csd=d2lkZ2V0TmFtZT1zcF9ocXBfc2hhcmVk You will need to watch with the switching buck/boost converters, some may have issues between positive ground and negative ground systems and that isn't always spelled out until you hook it up. A low tech way to reduce the voltage for variable current draws is to use a high wattage light bulb, may take some trial and error and may need to parallel a few bulbs to get it to work or try a variety of bulb variety's and wattages. Several high wattage 6V filament bulbs in parallel might work. The filaments in incandescent bulbs actually changes resistance from cold to hot so it tends to act as a current and voltage regulator. 1 Link to comment Share on other sites More sharing options...
Studebuddy Posted March 26 Share Posted March 26 ABear could be right about a step down module. That looks like it could work, but you should definitely build a box around it. But Dave is also right, you may just need to try a resistor in series. If you think you have the resistor right and it is still sounding sluggish, maybe it is time to service your horns internals. See if it is dragging on the bushings. Any resistance that slows the mechanical parts from spinning freely or a poor electrical connection caused by worn springs or brushes will affect the horns performance. When these horns are due for service, they can run a little slow. Maybe check/replace the springs and brushes. One other thought, did you wire your horn in with wire that will support the current draw of a 6-volt system? 6-volt wiring is thicker than 12-volt. If the gauge of your wiring isn't up to snuff, your horn won't receive the resources it needs and you run an chance of melting your wires. Link to comment Share on other sites More sharing options...
dodge28 Posted March 28 Share Posted March 28 If the 6 volts horn which is what you have does not croak well it may need servicing . Inside it has brushes and springs just like a generator .the armateur needs cleaning. There is a possibility the winding wires may be burnt and in that case have it rewired. Check the diapharam for rust and holes. Link to comment Share on other sites More sharing options...
Dipityro Posted April 16 Share Posted April 16 (edited) Dealing with voltage can be tricky, especially with older equipment like your klaxon horn. It's cool that it has sentimental value from your grandfather! So, here's a little story that might help. I once found this vintage radio at a flea market. When I plugged it into a modern outlet, it crackled like crazy. Turns out, it was designed for a lower voltage system. I ended up using a voltage regulator to get it just right, and now it plays my favorite tunes perfectly. For your horn, have you considered using a voltage regulator or maybe even a resistor to fine-tune the power? It could help balance out the speed and volume, making it just right for your Jeep. Oh, and I stumbled upon this cool train horn online (https://bosshorn.com/products/milwaukee-train-horn) that might give you some insights too. Edited April 18 by Dipityro (see edit history) Link to comment Share on other sites More sharing options...
ABear Posted April 16 Share Posted April 16 10 minutes ago, Dipityro said: So, here's a little story that might help. I once found this vintage radio at a flea market. When I plugged it into a modern outlet, it crackled like crazy. Turns out, it was designed for a lower voltage system. I ended up using a voltage regulator to get it just right, and now it plays my favorite tunes perfectly. Early vintage tube radios for homes can be found that use multiple battery voltages, use 115-130V AC OR 32V DC. The 32V DC versions were designed for rural homes and farms that did not have commercial grid power and often the rural homes and farms would have a DC generator which typically the output was 32V DC.. One must be careful when dabbling in old vintage radios and study up on the models before committing to powering it up. Generally not a good idea to randomly plug them in and power up until all the old dried out caps have been assessed and/or replaced. Link to comment Share on other sites More sharing options...
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