Take a feed from the battery, that has to be DC. I assume it does have a battery? An alternator rectifier for a few $ would change the AC to DC for you.
Car systems generally go 16v and higher too. I used this super cheap and simple diy driver for several off-road headlights and it works good. I use a different regulator though, the LM1084IT-ADJ. You need a small heatsink for the regulator.
EDIT: you don’t want too much of a voltage differential though. You would probably want 3 led’s in series. Voltage drop out is 1.25v. So 3 typical leds and the regulator would consume 10.25v. The regulator would burn up the rest of the voltage.
I’ve used that too, is simple and works well…
Edit, reading the comments, a 10 watts resistor is need it to drive 3x 3 watts Leds, so, maybe a large one to drive 10 watts Leds like the XM-Ls
I was looking at that one. It doesn't specify AC voltage though, so is AC input ok for that one? What about it's limit of 16v whereas I'm measuring up to 18.25v? It's also a little pricey.
I wondered about a feed direct off the battery (though that is much more involved as far as routing wire). Some sort of regulator "module" that I could mount to the frame and utilize would be ideal. Any links to a pre-made one of these?
-Garry
I think you would need a 3.75 watt resistor (1.25v x 3 amps). The amps don’t multiply in series. I would use a larger resister though. 5 amps. Some people like to use double the size calculated.
I dont think that this driver can handdle with AC, you must use a Diode bridge before the driver,
I have a few of this that I think can do the job, but I am not sure if can handdle more than 12volts, maybe 16volts, maybe can do the job if we add some diodes to the input to down a little the voltage
http://www.fasttech.com/products/1612/10001423/1110710-12v-3x1w-constant-current-led-driver-2013
Anyway we need more power, so lets try another, this one can drive just one Led and 650ma
So, I think that this one will be the right one, you can adjust the output voltage and get 3amps for the 3 Leds in serie
This one work too
But, because their are DC/DC you will need to add a diode bridge retifier first
Looking for a respond I ask my same dude…
I will choice this options best…
Oh, the driver I spoke of was for dc only. I’ve never done it, but I’ve seen very simple dc converter circuits using just 4 diodes.
EDIT: So is your rectifier in the same location as the battery?
EDIT2: The above post is the diy rectifier I was speaking of.
You talkin' to me? (Said in my best Brooklyn accent.) Does my mower even have a rectifier? I don't know. Where would I find it?
I like those modules, but wish they incorporated AC to DC (or that I could simply). Guess I would just adjust those blue pots for an output voltage within range of my driver's input range (the 3v to 15v). Now the problem is having all of this circuitry put into some sort of case that I can have semi-waterproof. I'd still prefer something "plug-n-play".
-Garry
The rectifier is the thing that converts AC to DC. It is usually inside the alternator. You all are talking about AC. Somewhere, the AC has to be converted to charge your battery.
Ok, so I need to find my alternator (is that likely under the engine shroud driven by the flywheel?) and tap off the line between the rectifier and battery? What kind of voltage should I expect coming out of the rectifier? 12v? 13.8v? 14.4v?
Why on earth did they run AC to the headlights in the first place? Seems like DC would have been easier.
Thanks,
-Garry
I don’t know. It sounds unusual. I would think the rectifier would be somewhere away from engine to reduce vibration and heat exposure. Probably on the frame.
I just seems weird. I would expect the whole vehicle to be 12vdc based.
I just perused some lawn mower forum posts (yes, there are even "tractor-aholics") and my head is spinning a little. Seems a dual stage AC & DC output system is common, although I am still not understanding why the AC. Apparently sometimes the DC output is only half-wave (think that's what I read) and simply pulses DC current. One guy mentioned when he rewires a mower he installs a full-wave rectifier for better charging and higher output which can even run at least a single 55w halogen light bulb. He suggests checking Ebay for used motorcycle or ATV rectifiers.
Perhaps I'm best to just wire from the battery! But will my driver work okay that way with DC voltage fluctuations and such?
-Garry
It should be ok. Probably won’t last as long with all the fluctuation. A diy rectifyier like ChangChungLeds was talking about is cheap and real easy. Basically just 2 diodes connected opposite on each of the 2 feed wires. Since diodes only let electricity flow one way, you can combine the 2 positive rectifier outputs to get DC+ and the 2 negative facing diodes to get DC-. Probably want to add a capacitor between the 2 DC lines to smooth out some noise.
I would like to adress this point since I cannot see a response. Automovite supplies are really evil. Quote from Linear Technology datasheet :“remember: you are plugging into the power supply from hell!”
This is very true. They are quite big currents in the system, sometimes connected with screwing connectors which might move unseen an can cause load dumps which lead to mean voltage spikes etc. Ignition might add to that.
If you want to use modern electronics on such a supply, please use at least an inductor (47µH+, adequate saturation current) followed by a bidirectional supressor diode as input protection.
It might work for years without, but it might also turn into a ball of fire after the first cranking. I would not save on that two bucks worth of parts.
Ok, point taken. I need a simple plug-n-play setup then. I'm no electrical engineer.
-Garry
I would just custom make a ghetto flashlight mount out of a tubular pool floaty and stick it in one of the beer holders .
You did buy a lawnmower with at least one beer holder didn't you ?
Building it is thankfully not more complicated than soldering a few wires together (3 solder joints ). But I have no clue about US based electronic part suppliers. I first thought of radioshack, but they seem to have mostly consumer electronics.
He he he! Well, I was trying to avoid the ghetto look . . . this time around!
-Garry
Beer holder? This is a family-friendly forum. Those are for holding tea. Long Island Ice Tea.
The super simple diy driver I linked is 2 components and costs very little. I would try it and if it fries, C’est la vie.
What type of led and what amperage do you want to drive them at?