LED Based Handycam Light Project, Aug '06

Sanjiv Dutta, B.Tech,

Senior Systems Analyst & District Informatics Officer,

Darrang District, Assam, India,

email: san011070@yahoo.com

 

Dedicated to :-

                  LIKU (wife), who kept me free of all domestic burdens & child-keeping to concentrate on my work...days after days!

 

Acknowledgement:-

                Dick Cappels & his website, and some other sites from which I collected lot of practical info. about LEDs and LED based Ckt. design.

 

  • Ckt. Components:-

  • Cells used:

  • The Challenge :- The LEDs I used found to have safe & fair ratings lower than its rated parameners. Again the input may vary form 3.6 v (When fully charged) to 3 v (after prolonged use). LEDs are very sensitive to voltage fluctuations. Secondly, you can operate an LED without damage at its maximum raings, but will not get proportionally more light, and it will significantly shorten its life. So its wise to use it under safe ratings and get fair light output rather. But I can't use a voltage regulator IC or Ckt.  to operate within such a small margin below 1 v! Kindly let me know if there is any, please.

     

  • The Solution:- I have come with a naive solution, but a working one. I put resistors to drop the supply voltage when needed, by means of a 3 position switch as described in the Ckt. below. (mail me for ckt. diagram)

              Now the next problem was, since it is very possible for someone to put new cells in, while the switch was in 'No Resistance' or 'Full Voltage' position. So LEDs will receive over voltage! That may partially damage the LEDs or atleast shorten their lives. So I made a mechanically coupled that Switch and the battery compartment lid, in such a way that the lid gets locked when the switch is in 'No Resistance' or 'Full Voltage' position.

 

 

Tools used:-

         Hacksaw, Chisel, Wire cutter, Tools form Biology Tool Box, File, Sandpaper, Soldering Iron, Hand-driller, Adhesive.

 

 

The Project Cycle - Captured in Video Stills

My workstation!

A 4" x 4" plastic switch-board

Hole on backside for battery compartment

 

the 3 cell battery compartment, hard to find. Found from a telephone receiver set. Cut with hacksaw & filed.

This weird looking part lying near the battery compartment is a lever and should slide into the notch of the opening lid of the battery compartment, and thus lock it.

 

This Ckt. has an On-Off switch (Red one), and a 3 position switch (black one) which will determine the resistance level:-  and thus the input voltage to the LEDs.

Interesting Fact: The Red cap of the On-Off switch was actually made from a red toothbrush handle.

The lever fitted into the voltage limiting switch. To open the battery lid, the switch must be  positioned in '1 Ohm' position.

White LED Array. 5 rows. 4 in a row. Total 20.

LED Ratings: MAX : 30 mA, 3.6 v.

There was no ratings info. available. So found by experimenting only (and blowing out a few :-( ).

 

The jumpers were made out of trimmed LED legs!

 

Some small parts made of flat bottom of the telephone receiver (Cutting with hacksaw, heating & bending, drilling, filing). These parts are brackets to hold the Ckt. boards

 

 

 

 

The flash hot-shoe!

Again made from flat bottom of the same receiver. The front side was narrowed & smoothened to allow easy insertion into the flash-mount.

Things are getting into places...

 
 
 
 

A CD jewel case will be our light's front cover

Cut, filed & pasted into place.

 

Let there be light!
 

Results:
Dummy, with Ambient Light only:-

 

 Dummy, with Ambient Light & LED Light:-

 

At 1 Mtr

 

At 2 Mtrs.

 

At 3 Mtrs.

 

'Orchid' Without LED Light

'Orchid' with LED Light at 1.5 Mtr.
 

Conclusion

 

        The LEDs available commonly here in INDIA are cheap and unbranded. And actual LumiLEDs are too costly for amateurs like me ! Anyway, the light is working fine as a filler upto 3 Mtrs., though not as the main source.

"Bye bye!"

 

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