# Led light and bridge rectifier on 10hp Tecumseh



## Coyotey (Oct 31, 2016)

Hi folks new here so please forgive me if this has been covered before.

I have an old Ariens ST1032 with a 2 year old 10hp Tecumseh Snow King motor. There is no battery. I want to mount a single 27w led worklight as a replacement to the old one from back in the stone-age.

I have a single yellow wire with a black sock ending in a single plasic plug sticking out of the motor. I understand that I will need to hook up a bridge rectifier between the light and this wire because it's AC coming from the motor and the LED will need DC. 

So here's the wiggle: there are 4 points on a bridge rectifier - 2 for AC and 2 for DC - so how do I hook this up given that I only have 1 AC wire out????

Any help would be appreciated!


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## classiccat (Mar 1, 2014)

Coyotey said:


> Hi folks new here so please forgive me if this has been covered before.
> 
> I have an old Ariens ST1032 with a 2 year old 10hp Tecumseh Snow King motor. There is no battery. I want to mount a single 27w led worklight as a replacement to the old one from back in the stone-age.
> 
> ...


the other AC lead would go to ground (i.e. your engine block).

double check that stator output to make sure it's pure AC... set your multimeter to DC and measure the stator output to ground. if you get any DC voltage, then you have a diode in there already (serving as a half-wave rectifier). that diode would have to be removed before installing a bridge (full wave) rectifier.


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## Coyotey (Oct 31, 2016)

classiccat said:


> the other AC lead would go to ground (i.e. your engine block).
> 
> double check that stator output to make sure it's pure AC... set your multimeter to DC and measure the stator output to ground. if you get any DC voltage, then you have a diode in there already (serving as a half-wave rectifier). that diode would have to be removed before installing a bridge (full wave) rectifier.


Thanks Classiccat for your response!

I just measured and I'm getting 14+ on AC at full revs and 0.1-0.2 on DC (so basically zero).

So then I need to get the bridge rectifier - and if I understand correctly, I connect the AC wire from the motor to it's appropriate place on the rectifier and then make a wire to ground from the other AC connection on the rectifier. Then the positive on the LED would connect to the appropriate spot on the rectifier and the other to ground?

Where is the best place to have a switch? Does it make any difference if it goes before or after the rectifier?
Also: what would be the suitable size of rectifier for this motor and for this 27w LED application?

Again, thanks for your insight!


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## scrappy (Dec 7, 2014)

Water proof rectifier, also has mounting hole. I think jeeps used this so mayb find at autoparts store.

Bridge Rectifier 50 Amp 1-1000 Volt- KBPC50A10 - TMC USA Aluminum Casing | eBay


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## EdwardC (Sep 26, 2016)

I don't think it would make a difference for which side of the bridge rectifier to put the switch.

I think that any bridge rectifier you find will be adequate for your application. 27W is just under 2A at 14VAC. Were you planning to put any filtering capacitors on the DC side? A full bridge rectified and filtered 14VAC input would be close to 20VDC (ignoring the voltage drop of the two diodes in the rectifier). I'd say any rectifier capable of 5A would do fine. The one scrappy found is overkill, but it's cheap, waterproof and easy to mount, so why not!


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## Coyotey (Oct 31, 2016)

Thank you for your help gentlemen. 

Part is orderred and I can't wait to see this LED work. We live so far to the north here in Norway that it gets dark at 2:30-3pm so most of snow clearing happens in pitch dark after work. So, let there be light then!

Cheers!


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## Coyotey (Oct 31, 2016)

EdwardC said:


> I don't think it would make a difference for which side of the bridge rectifier to put the switch.
> 
> I think that any bridge rectifier you find will be adequate for your application. 27W is just under 2A at 14VAC. Were you planning to put any filtering capacitors on the DC side? A full bridge rectified and filtered 14VAC input would be close to 20VDC (ignoring the voltage drop of the two diodes in the rectifier). I'd say any rectifier capable of 5A would do fine. The one scrappy found is overkill, but it's cheap, waterproof and easy to mount, so why not!


You mention filtering capacitors on the DC side...what function does this perform? Do I need one?


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## classiccat (Mar 1, 2014)

that smoothing capacitor takes the rectified sine wave and smooths-out the peaks; in the case of an LED lamp, it will minimize/eliminate any flicker.

you're opening a can of worms adding a switch to this circuit. The no-load voltage can spike very high causing premature failure of your LED lamp.


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## Coyotey (Oct 31, 2016)

classiccat said:


> that smoothing capacitor takes the rectified sine wave and smooths-out the peaks; in the case of an LED lamp, it will minimize/eliminate any flicker.
> 
> you're opening a can of worms adding a switch to this circuit. The no-load voltage can spike very high causing premature failure of your LED lamp.


Is it then best to just drop the switch and let it light constantly? I have only a rudimentary understanding of electronics - wouldn't the no-load current just stop at a turned-off switch - thus not affecting the light?


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## classiccat (Mar 1, 2014)

Coyotey said:


> Is it then best to just drop the switch and let it light constantly? I have only a rudimentary understanding of electronics - wouldn't the no-load current just stop at a turned-off switch - thus not affecting the light?


That's correct; it's easiest to let that thing shine its butt of even in broad daylight 

It's not a matter of current...but rather potential (voltage). You could install a voltage regulator to peg the voltage below the maximum LED voltage however there's no real need for that added cost / complexity.


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## EdwardC (Sep 26, 2016)

I tend to agree with classiccat. If not only for the no-load protection, just to make it simpler with less points of failure. If anything, attach the LED with a connector so that you can disconnect it before you start the blower if the light being on is an issue for any reason.

As for the filter capacitor, depending on the LED light you use, you may notice flicker, so it doesn't hurt to add a capacitor across the + and - of the rectifier output. Just curious, what LED unit are you using? Can it handle ~18VDC?


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## Coyotey (Oct 31, 2016)

Ok I'll drop the switch! I completely agree about one less point of failure!

The LED light is rated for 12-24V and 27W.


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## Taurus04 (Dec 10, 2014)

Don't want to hijack the thread, but I am in the process of doing this as well. I have hit a snag in that the "deck' where the shift plate is on my Craftsman 10/32 is too low and the light is blocked by the discharge chute as the only hole is on the left. I believe the Craftsman blowers used a handlebar mount. Has anyone who has added the LED light come up with this issue and found a bracket?

Thanks.

Please delete if I am hijacking.


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## Coyotey (Oct 31, 2016)

Taurus04 said:


> Don't want to hijack the thread, but I am in the process of doing this as well. I have hit a snag in that the "deck' where the shift plate is on my Craftsman 10/32 is too low and the light is blocked by the discharge chute as the only hole is on the left. I believe the Craftsman blowers used a handlebar mount. Has anyone who has added the LED light come up with this issue and found a bracket?
> 
> Thanks.
> 
> Please delete if I am hijacking.


Hi! I don't know about the bracket, but have you considerred mounting 2 lights - one on each side? The shadow from the chute wouldn't be an issue then? Just drill a new hole?


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## Kiss4aFrog (Nov 3, 2013)

Or if you want to switch it off during the day make sure to turn it on or off BEFORE starting the engine. You could mount it under the dash in a slightly inconvenient location just to make sure you don't bump it during operation.

As for the 27 watt light, are you sure the Tec engine will run it ?? What was the stock bulb your replacing running ?? I know my older Tecumseh only supports 18 watts.


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## Coyotey (Oct 31, 2016)

Kiss4aFrog said:


> Or if you want to switch it off during the day make sure to turn it on or off BEFORE starting the engine. You could mount it under the dash in a slightly inconvenient location just to make sure you don't bump it during operation.
> 
> As for the 27 watt light, are you sure the Tec engine will run it ?? What was the stock bulb your replacing running ?? I know my older Tecumseh only supports 18 watts.


I'm pretty sure it will run a 27W. Apparently this 10hp Tecumseh is one of the last ones ever produced. I deduce this from youtube and others that have done the same, either by combining two lights which add up to 27W or a single. "Doniboy" also has a video out where he's mounting a 27W. Keeping my fingers crossed - Getting the bridge rectifier next week sowe'll see soon enough


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## dbert (Aug 25, 2013)

Coyotey said:


> So then I need to get the bridge rectifier - and if I understand correctly, I connect the AC wire from the motor to it's appropriate place on the rectifier and then make a wire to ground from the other AC connection on the rectifier. Then the positive on the LED would connect to the appropriate spot on the rectifier *and the other to ground*?


To utilize the full wave you need to keep your AC and DC grounds isolated. Meaning you will run both the pos and neg (DC) wires from the rectifier to the LED.

AC (stator) wire to AC+
Chassis ground wire to AC-
LED positive wire to DC+
LED negative wire to DC-


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## Ferret (Oct 4, 2016)

classiccat said:


> that smoothing capacitor takes the rectified sine wave and smooths-out the peaks; in the case of an LED lamp, it will minimize/eliminate any flicker.
> 
> you're opening a can of worms adding a switch to this circuit. The no-load voltage can spike very high causing premature failure of your LED lamp.



I understand the voltage for the capacitor, but what mfd am I looking for?


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## Kiss4aFrog (Nov 3, 2013)

It's in the first post about 5 or 6 photos down. http://www.snowblowerforum.com/foru...rading-your-snowblower-lights-led-lights.html


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## Kiss4aFrog (Nov 3, 2013)

Taurus04 said:


> I have hit a snag in that the "deck' where the shift plate is on my Craftsman 10/32 is too low and the light is blocked by the discharge chute as the only hole is on the left. I believe the Craftsman blowers used a handlebar mount. Has anyone who has added the LED light come up with this issue and found a bracket?.


You can pickup a piece of square tubing at a box store and lay it across the handlebars at a height where the light gets the best chance to clear the chute. You can use self tapping screws to attach it or use small U bolts like on a cars exhaust system to fasten it. Depending on the power you have one in the center or one at each end.
You might also find something at a bike store or online relating to mounting something to a bikes handlebars that might work out. I used the square tube and U bolts to mount twin lights on one I had and it worked great. I was copying the way Snapper did the headlights. On my Snapper it uses a flat bar, U bolts and little risers at the end for mounting the headlights.
Photo is my 1030 missing the lights. Will be mounting LEDs.


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