Electronics, Lighting, & Gadgets - My updated Instructable for a DIY Halogen Light

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samsmeg
01-30-09, 05:48 PM
Hi guys,

just wanted to share my updated DIY light. I started out using left over R/C racing pack batteries but I think they were pretty dead and so I left the project for a while. Then I started commuting again- 14miles. The route is mostly country roads and I felt I would much more comfortable with more light.

So I got two new 7.2v 2000mah batteries. I changed the connectors on them to banana-esque terminals so that they could be linked series for 14.4V. I found a water bottle that would hold both batteries but I still need to make a hole for the battery wires to protrude. I've also still only got a flood pattern bulb which is a nuisance- will be changing that shortly to a narrow beam (spot or something).

This thing is bright though! Check out my shoddy phone pictures on the Instructables website for an idea----->

http://www.instructables.com/id/Homemade-Halogen-Bike-Light/?ALLSTEPS

cod.peace
01-31-09, 08:35 PM
Have you thought about adding an NTC thermistor inside the light housing for a simple soft-start to protect the bulbs?
samsmeg
02-01-09, 04:12 AM
No I haven't actually,

I was thinking about that but I was unsure of how to get the soft start. So its a NTC Thermistor? Soldered in series with the circuit? I have a few electronics stores around so I could probably get the component

Sam

ellerbro
02-01-09, 08:00 AM
The light looks good. I love DIY stuff. One issue caught my eye though. I wouldn't use phone connectors for power because positive/negative can briefly short together when inserting/removing them. Their current rating may also be inadequate. I'd use barrel connectors (DC power connectors), for example:

Plug (http://www.mouser.com/Search/ProductDetail.aspx?qs=yPI4UV3pIw3RhLPOoItSzw%3d%3d)
Jack (http://www.mouser.com/Search/ProductDetail.aspx?qs=I3kMT7EEIOXXob2Ub%2fzU5g%3d%3d)

I might have to use your PVC pipe approach for a DIY rear light I'm working on. Thanks for sharing.
cod.peace
02-02-09, 09:01 PM
No I haven't actually,

I was thinking about that but I was unsure of how to get the soft start. So its a NTC Thermistor? Soldered in series with the circuit? I have a few electronics stores around so I could probably get the component

That's right - they're rated by their room temperature resistance, say 5 ohms, which then drops to maybe 0.05 ohms or something when they're hot. It's not going to be as effective as a real electronically controlled softstart, but for a bike light though, at around $0.50 ea they seem like a good solution. Here's a website for one brand: surge-gard (http://www.rtie.com/ntc/surggard.htm)