How I Built My Own MTB Light

[BrewMaster]

Originally Posted by OffRoadie

You would need to find the voltage for NiMH that indicates that the battery is low. You then have a circuit that detects the low voltage and hits the LED. They might make IC's for this sort of thing.

EDIT: Here's one designed for Lithium Ion batteries, but might be able to be adjusted for NiMH.
http://www.linear.com/pc/downloadDoc...63,P2133,D1290
Linear Technology LTC1998

Another one: Single Supply Under-voltage/Over-voltage IC
http://www.linear.com/pc/downloadDoc...,P30132,D17418
Linear Technology LTC2912.

Both of those data sheets are way over my head. Thanks though.

Originally Posted by COLEKO

I whould use somthing like a deans plug.. If you come to the loop next Thursday Ill give a male female plug to try out.
http://www.wsdeans.com/products/plugs/index.html

They also make a Micro plug and you can pick those up at Hobby People or any hobby store.

If you could bring a male-female plug to the loop next Thursday for me to try, that would be awesome. Thanks.

[mcgyver0302]

Deans... definitely Deans... they won't come apart on you while you're mashing 40+ on those night downhill sessions... right Dino? And thanks for the mention of Ford electronics. I have been going to them since I was nine, great people. Just my .02

[92se-r]

None of these low voltage detectors are specific for any sort of battery. They say they are meant for Lithium Ion batteries, because they are usually what are used in 3.3V applications. That is why they are only rated up to 6V. These would not work for your batteries.

What I would recommend is use a LM317 or equivalent linear regulator for a regulated 5V output or something. Then use a LM139 comparator powered off this regulated output. Then use a voltage divider to set your reference voltage so that when your battery voltage dips below a certain voltage, it trips the comparator and drives a MOSFET to turn on a buzzer. That is what I am going to do on my personal light I'm building. There is no way you will even notice a little LED that turns on when your battery voltage is low while you are riding. I'm going to have a 100db piezo buzzer that I can manually override so I don't have to listen to it for the rest of the ride, but I know that I've got about 30-45 minutes of battery life left.

It only adds about 10 small parts that you could easily package.

Originally Posted by OffRoadie

You would need to find the voltage for NiMH that indicates that the battery is low. You then have a circuit that detects the low voltage and hits the LED. They might make IC's for this sort of thing.

EDIT: Here's one designed for Lithium Ion batteries, but might be able to be adjusted for NiMH.
http://www.linear.com/pc/downloadDoc...63,P2133,D1290
Linear Technology LTC1998

Another one: Single Supply Under-voltage/Over-voltage IC
http://www.linear.com/pc/downloadDoc...,P30132,D17418
Linear Technology LTC2912.

[OffRoadie]

You're right, I didn't notice the 6V supply maximum. However, the second one I posted shows that you can use it with voltages higher than 6V, if you put a resister into Vcc. Application shows an example with a 48V supply.

[Schecky]

Here's another design I am considering:

http://forums.mtbr.com/showthread.php?t=354430

[BrewMaster]

Originally Posted by 92se-r

None of these low voltage detectors are specific for any sort of battery. They say they are meant for Lithium Ion batteries, because they are usually what are used in 3.3V applications. That is why they are only rated up to 6V. These would not work for your batteries.

What I would recommend is use a LM317 or equivalent linear regulator for a regulated 5V output or something. Then use a LM139 comparator powered off this regulated output. Then use a voltage divider to set your reference voltage so that when your battery voltage dips below a certain voltage, it trips the comparator and drives a MOSFET to turn on a buzzer. That is what I am going to do on my personal light I'm building. There is no way you will even notice a little LED that turns on when your battery voltage is low while you are riding. I'm going to have a 100db piezo buzzer that I can manually override so I don't have to listen to it for the rest of the ride, but I know that I've got about 30-45 minutes of battery life left.

It only adds about 10 small parts that you could easily package.


Terrin

When you do this, can you please post up the parts and design you use? I may try to copy your work. Thanks.

Originally Posted by Schecky

Here's another design I am considering:

http://forums.mtbr.com/showthread.php?t=354430

Dude, these Cree LEDs look awesome!

http://www.dealextreme.com/details.dx/sku.1302

http://www.dealextreme.com/details.dx/sku.2394

Perhaps I will change LEDs on my helmet mount light that I will build soon.

[tkblazer]

yup i posted that scar thread in my other thread about the lupines...

i like this design as well, might have to copy it

http://forums.mtbr.com/showthread.php?t=248012

[Fired Yo Momma]

First of all cold job BrewM for your lights look good. You have inspired me, really!

Anyways you can also get parts at Mar Vac Electronics in Costa Mesa or Ford Electronics, I think they are in Anaheim or Fullerton.

[BrewMaster]

Nice find Nam. This would make a nice housing:

http://myfwyc.org/bikeled/ConstructionSteps.html

Chewyeti, do you have a band saw or other cutting implements? We could make some of these as helmet mounts. They look pretty sweet.

[spookydave]

Hey Brewmaster, I can help you out on a housing.
I have a few cutting tools over here.

[stjunkie]

Just thought I'd throw this out there for the STR DIY'ers. I have access to a PCB cutter at work and could make custom PCB's if you need them. I can only do double sidded copper boards with unplatted via holes. I would just need a hand drawn sketch or a .dxf file to make them. I have a bunch of different materials but the most common are .047 and .062 polyimide.

[BrewMaster]

Originally Posted by spookydave

Hey Brewmaster, I can help you out on a housing.
I have a few cutting tools over here.

Where are you located Dave?

At this rate, we may have STR lights on sale before we get another batch of jerseys made!

[tkblazer]

Originally Posted by spookydave

Hey Brewmaster, I can help you out on a housing.
I have a few cutting tools over here.

i was waiting on you machinist bubbs to come out of the wood work...

sam, that design is so simple yet seems to work really well for the original designer..

[spookydave]

Originally Posted by BrewMaster

Where are you located Dave?

At this rate, we may have STR lights on sale before we get another batch of jerseys made!

My shop is in Placentia.
I've been thinking about doing a run of lights for awhile now. Now with STJunky with the PC board hook up I bet we could really make something nice.

[tkblazer]

i'll post up when i am about to make an order on led's and crap, if people are interested they can PM me when the time comes to save on shipping.

[BrewMaster]

Originally Posted by tkblazer

i'll post up when i am about to make an order on led's and crap, if people are interested they can PM me when the time comes to save on shipping.

Good idea. I'd be in to save on shipping.

I think my next light is going to have 3 Cree LEDs on it. I will definitely use a wired buckpuck next time instead of trying to solder it all in such a small space.

This guy's DIY site is pretty thorough. I may have to copy his design with my own modifications.

[spookydave]

what about making the housings round kinda like these?
http://www.ayup.com.au/colours.html
Could do doubles, tripples and quads. Maybe a tripple (flood-spot-flood) on the bars with a double (spot - spot) on the lid.
Maybe mount the batts and buckpuck in a waterbottle and have some small switches on the bar.

[tkblazer]

that would be sweet dave, i'll have to look up the thread where this guy milled his own round housing.