PWM control for B&D Grass Trimmer

[Moses_C]

Cheaper to just buy a better one

Yeah, i've considered that already long ago, to be honest...i was thinking of switching over to a small lawnmower instead of a handheld trimmer, as it aches my arms after each usage apart frm the numbing vibration..the only thing is, mowers are not cheap in my country and its actually sth like a specialty product...most people here like to do away with their lawn and tile it, to avoid the hassle of up keeping it. But love my little lawn... :-D

[underthetire]

Got a smart phone? There are some handy free apps that help balancing quite well. I have one I use to help balance my model jets.

[Moses_C]

Got a smart phone? There are some handy free apps that help balancing quite well. I have one I use to help balance my model jets.

Oh i see..however i dont have one. Thanks.

[Moses_C]

Ok guys, this it is the light dimmer i've bought and put togerther. I've attached some pictures of it...it is working well with a light bulb.

Now, i havent tested it with my trimmer yet...so, would like to know b4 hand, will it burn the trimmer or cause some serious problem with this type of dimmer? From what i do know is, if an electric motor runs too slow, it may cause the thing to burn..or sth bad may happen.

The dimmer is rated to handle 500W...while my trimmer is just 300W, running at 10000rpm at normal usage. As mentioned at the start of thread, i plan to reduce the speed to at least half, or to a level it wont generate numbing vibration.

Any suggestion or comment on this would be great...simply bcoz i dont wanna fry it so soon! ...that's all.

Thanks a lot again!

[Al_The_Man]

Probably the worst case scenario is the Triac in the dimmer would short or open, if so, either way it would not harm the trimmer?
Al.

[Moses_C]

Probably the worst case scenario is the Triac in the dimmer would short or open, if so, either way it would not harm the trimmer?
Al.

Hi Al! Good to hear from you again!

Thanks for telling...ok, i'll try later then.. ^__^

I just managed to resize and upload the photos...sorry bout that. There are some of the internal pictures of the dimmer assembly..hope it is somewhat useful to you and others. :-P

So, correct me if i'm wrong...when i use it, i should not turn it all the way down to zero...that is almost off, right? Also, how slow actually SHOULD i go? Is there a line i shouldnt cross??

Tq Al.

[keebler303]

If the motor has a fan on it, that is what is relied on to cool the motor. If you go too slow, the motor may still be drawing a large current, but the speed will be lower so the cooling will be less efficient and the motor will get hotter. I would say just monitor the motor and as long as it's not getting too hot you should be fine.

Matt

[Moses_C]

If the motor has a fan on it, that is what is relied on to cool the motor. If you go too slow, the motor may still be drawing a large current, but the speed will be lower so the cooling will be less efficient and the motor will get hotter. I would say just monitor the motor and as long as it's not getting too hot you should be fine.

Matt

Yep, thanks Matt...i did just that, and managed to reduce the speed to such a comfortable level. I'm so happy everything work out so perfectly...with no additional heat nor heated up odour coming from the motor! Yes, even after extended usage time...just so glad all the effort invested was not wasted.

Thanks to you Matt...and everyone who contributed to resolving my problem.

THANK YOU!