FRIDAY, SEPTEMBER 6, 2019
DIY custom deep red flashlight
I admire the Rigel brand red astronomy flashlights (or torches) particularly
the small form factor units with the compact rectangular case. They
use nicely coloured red light emitted diodes, a common 9 volt battery,
and are very power efficient. Adjustable in brightness. I saw some
with neck straps. I considered building my own which I knew would
be a fun and relatively easy DIY project.
The image above shows the initial build with a pair of LEDs and the
brightness control. Note the hook-and-loop material and strap for
wearing the lamp on one's head.
A compact size was important to me. I wanted it as small as possible.
And it was important that I could use it like a head lamp, say if
I was working and needed my hands free. Or if I was sketching. My
old MEC camping head lamp was long-dead. The "clip lights"
I was using were fragile...
The photo above shows the working circuit board. The power switch
is not yet installed. Also the perf board has not been cut down.
The colour was important, i.e. the colour of the light produced.
Some red flashlights are more orange. I was after a very deep red
colour. And no white light. There are a number of flashlight and head
lamp designs that have white LEDs on board. Some even make you cycle
through the white mode in normal operations. I wanted none of that!
The 1.5 year build time may seem odd but it was the head-mounting
issue that road blocked me for a long time.
The photo above shows the update, with 4 LEDs onboard, versus the
original two.
It works great! I regularly use it.
technical info:
- pulse-width modulation (PWM) circuit design for high efficiency
- adjustable brightness (via rheostat)
- germanium diodes for broad control range
- can be used in different configurations or ways
- held in hand
- draped from neck with lanyard
- worn on head with adjustable strap
- specifically uses dark or deep red coloured LEDs
- 660 nm wavelength 2800 mcd
- expandable design to suit a different number of LEDs
- initially two 5mm LEDs; now four
- removable or interchangable (!)
- no white bulbs!
- standard battery (not nasty coin-style)
- case dimensions 9.5 x 6.0 x 2.5 cm
- note: this is not water-proof
build costs:
A commercial unit such as the Rigel "Starlite mini" with
2 red LEDs costs USD $25.
- Sayal electronic parts CAD $20
- digi-key parts (including shipping and taxes) CAD $8
- bits and bobs in my parts bins - free kinda?
- Velstretch strap (building store) CAD $5
research and build time:
- start date 26 Nov '09
- finish date 7 Feb '11
- approx. 15 hours
references:
lessons learned?
- germanium diodes are sensitive to heat
- trialing the physical board layout is always illuminating and
revealed minor interference and network routing issues
- Hammond case 1591A is a little smaller but does not specifically
have a spot or space for a 9v battery—but you can get it in
a cool clear red colour!
- the Celestron Night Vision is similar to the Rigel
- the Orion RedBeam II is like the Rigel (who copied whom)
- the dimensions of a 9v battery are height 48.5 mm (including the
terminals), length 26.5 mm, and width 17.5 mm
things I might add or change:
The diagram above is from 123D and shows the first object I drew
as an exercise in my 3D printer class at the TPL.
- while happy with the result, it is about twice the volume of the
Rigel design, so I continue to think about a new version with a
small project box—or a custom 3D-printed one!
- when I showed Phil, he said "it's heavy," again an indicator
that the case is perhaps too large
- really didn't need the right-angle socket mount thingee
- I was future-proofing the project but can't fathom why I didn't
fully wire up the board for additional LEDs
FRIDAY, SEPTEMBER 6, 2019
everything needed
Parts for the flashlight build. Tools, equipment, supplies, etc.
used.
- parts
- U1 - 555 timer (Sayal)
- R1, R2 - 1k resistors (Sayal)
- R3, R4 - 210 ohm resistors (one for each LED)
- etched perf board or PCB (Sayal)
- Q1 - NPN transistor (Sayal)
- C1 - 0.1 µF regular capacitor (Sayal)
- C2 - 0.01 µF regular capacitor (Sayal)
- C3 - 470 µF electrolytic capacitor (Sayal)
- project box, with 9v battery compartment, screws (Sayal)
- D1, D2 - old school Germanium diodes (Sayal)
- right-angle 8-pin DIP socket, optional!
(Digi-Key Canada ed58408-nd)
- P1 - 100k tiny thumbwheel potentiometer
(Digi-Key Canada 3352t-104LF-nd)
- LED1, LED2 - "super red" waterclear 5mm
(Digi-Key Canada 67-1612-nd)
- SW1 - small slide SPST switch
- 9v battery snap clip
- copper wire, sheathed and bare
- clear plastic sheet, for the lens
- screws
- rubber grommet, for internal spacer
- Velcro hook self-adhesive pad, 5cm square
- Velcro Velstretch strap (loop), 27" long
- eyehook, small
- lanyard and clip
- case, for easy transport
- computer resources
- ExpressSCH for circuit schematic planning
- ExpressPCB for circuit board planning
- the world wide web
- amazing Evernote
- Microsoft Visio
- testing
- Maxitronix Electronic Lab with breadboard for prototyping
- digital multi-meter
- alligator jumper cables, for jumping
- tools
- soldering iron, adjustable
- desoldering pump
- sponge
- helping hands
- alligator jumper cables, for heatsinking
- side cutters
- wire strippers
- tiny screwdrivers
- hacksaw
- sandpaper
- cutting knife
- heat gun
- drill and small bit
- eye protection
- mouth mask
- supplies
And I used a digital camera to photo-document things...
WEDNESDAY, SEPTEMBER 4, 2019
blog links - the build
Scattered through the blog proper are detailed reports and updates
on the build with some posts showing photos. Reverse chronological
order.
- upgraded
deep red light, 11 Apr '18
- new battery while sorting
some issues, 17 Mar '18
- not ready design a new case; made
a cap, 14 Nov '17
- misplaced, found it ahead of DSOs
before fog, 1 Oct '17
- played in Express to re-work PCB, 17 Apr '15
- registered for 3D
printing course, 17 Mar '15
- played with a compact case design in Visio, 24 Mar '14
- searched for small project boxes, 24 Mar '14
- found
red box from Hammond, 11 Feb '14
- showed light during nova
imaging, 18 Aug '13
- sketched with light during a
little bit of everything, 5 May '13
- showed light during sketching
night, 6 Apr '13
- inspected
deep red light, 25 Jun '12
- showed light at pre-work
party, 13 May '11
- first test while getting
ready for the finish, 14 Feb '11
- flashlight, headlight, deep
red done, 7 Feb '11
- found Velstretch straps, did
2 pi R math, 1 Feb '11
- needed a red headlamp during sketching, 20
Feb '10
- finished
circuit board of deep red light, 17 Jan '10
- laid
out circuit board deep red light, 8 Jan '10
- designed
the PCB for deep red light, 7 Jan '10
- finished
schematic for deep red, 3 Jan '10
- gifted
a deep red head lamp from MEC, 30 Dec '09
- very
happy with Digi-Key Canada, 15 Dec '09
- considered the deep
red design, 26 Nov '09
- inspected Rigel
flashlights, 3 Aug '08
|
|
links
|
