
---------------------- 
NOTES FROM THE BIKELAB 
Issue #2 -- 12/16/90 
by Steven K. Roberts 
----------------------

Copyright (C) 1990 by Steven K. Roberts.  All Rights Reserved.

	IN THIS ISSUE:
		A Booming Alias 
		Feedback and Questions 
		Snapshot of the Bikelab 
		LED Taillights 

	ROBERTS' LAW OF APPLIED MOBILE GIZMOLOGY:
	If you take an infinite number of very light things
	and put them together, they become infinitely heavy.

A Booming Alias 
---------------

	Well, this has certainly struck a chord!  As of this writing,
	367 people have responded to the announcement of reports from
	the bikelab.  This is gratifying, and a little scary:  now my
	blithe prediction of weekly publication has to be taken a
	little more seriously.  <gulp>

	You know, there is something subtle about this whole Grand
	Turing Machine project that I am just now beginning to
	appreciate.  I touched on it in issue #1 (where I commented
	that I am just project coordinator for the REAL wizardry that
	must be credited to industry), and it was brought into sharp
	focus by an article in the Oct 1 issue of EDN about Richard
	Stallman of the Free Software Foundation.  It spoke of the
	hacker ethic, which encourages cooperation and free sharing of
	information with the general intent of building the best tools
	possible, unhampered by legal constraints.

	I believe in this, but I've also seen the awesome power of
	competition.  It therefore seems that the best stance for me to
	take in publications about BEHEMOTH is to protect the
	intellectual property of my corporate sponsors, but otherwise
	disseminate the concepts and design details as widely as
	possible -- either for free, or in value-added form via the
	print edition of Nomadness <plug, plug>.  Industry has made
	this enterprise possible by contributing ideas -- and it's only
	fair for me to complete the cycle, so to speak, by freely
	sharing information in return.

	And this publication is the vehicle for that.  Enjoy, and
	please feel free to redistribute this without charge and write
	to wordy@bikelab.Sun.com with feedback and questions...

Feedback and Questions 
----------------------

	This regular column will present a few specific reader comments
	in each issue.  To maximize your chances of getting a letter
	published, please make your questions well-focused (I've had
	some that require about 10K of text for a cogent answer).  I do
	edit for clarity and brevity...

>From Brian Lloyd of Telebit:

	Last time I spoke with you, I enquired about sources for
	recumbent bikes.  I find the riding position on standard safety
	bicycles too uncomfortable (I have a neck and back malady that
	causes problems with the head-up riding position).  I would
	like to construct a smaller version of your bike without all
	the features you carry.  I would probably limit it to a single
	processor, cellular phone, and two meters.  There has to be a
	way for those of us without millions of $$$ to accomplish some
	of the same things that you have.

	One other item: the product that we (Telebit) have recently
	unveiled will be of interest to you.  It is an IP router that
	establishes its link with the network using on-demand dial-up
	links.  Imagine that someone in the Internet needs to establish
	a session with your bike (mail, transfer a file, etc.).  They
	simply route the packet to one of our NetBlazers and it calls
	your bike via cellular phone. Likewise you can initiate the
	connection via CellBlazer from your bike.  Imagine having your
	built-in SPARCstation on the Sun network wherever you go but
	having the phone connection active ONLY when there is traffic
	going back and forth.

				-- brian@robin.telebit.COM

Brian...

	Wow!  I want one.  I'm rapidly getting addicted to the Big
	Network... these are some pretty powerful tools.  They are
	changing my expectations about how datacomm from the bike
	should work:  stopping at the occasional pay phone and plugging
	in the cups no longer seems particularly appealing.  The
	product you describe sounds like pure magic, and the ideal
	solution for this nomadic application.  Where do I sign?  (NOTE
	to readers:  We have since spoken and this looks like it will
	indeed happen... watch future issues for details.)

	As to the recumbent, a good approach is to contact Dick Ryan
	about the Ryan Vanguard recumbent.  It costs about $1,000 and
	is one of the best made commercial recumbents I have ever
	seen.  The company is in Malden, MA at 617-324-1921.

	Two other resources of note are the Recumbent Bicycle Club of
	America ($15/year to RBCA, 427 Amherst St., Suite 305, Nashua,
	NH 03063) and the International Human Powered Vehicle
	Association ($20/year to IHPVA, P.O. Box 51255, Indianapolis,
	IN 46251-0255).  Both have excellent publications.

				-- wordy

A brief comment on the bike's TCP/IP link from Courtney Duncan, N5BF:

	Yeah, Cellblazer-like things are leaving hams in the dust.
	You're going to be able to remotely mount just about anything
	in the world just so you can talk to me on e-mail about how to
	make an amateur 1200 baud twice-per-day satellite connection
	(that will only work after lots of trying).

Hmm.

Responding to my comment about starting the next journey with RAGBRAI 
(across Iowa in July), Chuck N6GAL inquired:

	Does this mean you're not starting the grand tour from here?
	Will there be no opportunity for those of us still chained to
	our desks to spend a few days riding with you?

Chuck...

	Actually, there will be some kind of shakedown in this end of
	the world before July.  I rode all the way to Sunnyvale last
	week to visit Trimble Navigation and do an open house with
	Ampro, and even that short flat ride demonstrated how badly
	I've gotten out of shape.  I'm planning a one-week loop to
	Pinnacles National Monument sometime in the spring, and
	everyone interested is invited... I'll post the details to this
	alias as they develop.  Hope you can come along!

				-- wordy

Now a power management question from Larry Fiedler here at Sun:

	I understand that you rip out the power supplies on the
	computers and use your own +5V supply from the bike.  Does this
	cause you any problems, or is it as straightforward as I think?
	I suppose you need to solder in a power switch.  Is there much
	voltage level fluctuation, and if so does this ever cause a
	problem?

Larry...

	Basically correct -- I run a raw +12 (more or less) battery bus
	throughout the whole bike, and then spot-regulate with
	dedicated DC-to-DC converters tweaked to each load (MAX638 for
	most of the 5-volt stuff).  It's hardware intensive, but
	maximizes conversion efficiency.  The switching is all
	electronic via FETs, under control of FORTH tasks in the 68HC11
	systems.  Another benefit of this is minimization of noise
	propagation -- trash in one area is not likely to become
	global.

				-- wordy

Finally, this from Joe Reed, N9JR, somewhere in Wisconsin...

	Thanks for issue 1 - it blew me away.  Sounds like a ham
	dream!  Now since you have the HF antenna problem licked, are
	you running PacketCluster and have you developed the ability to
	QSY to the DX spot frequency?  That might make mobile dxing a
	bit easier on a busy highway.  Depending on the transceiver you
	use it should be a fairly simple programming task

				-- 73, Joe N9JR

Joe...

	<grin>  Well, now there's an angle!  Actually, I'm not much of
	a DX chaser -- my pleasure in ham radio is making friends, and
	the frenzy of a pile-up seems to accomplish quite the opposite
	if you're not careful.  Being on the bike in strange places
	might put ME in the hotseat, come to think of it... and an
	endless succession of "QSL, you're 5-9 in Kamchatka, QRZed?"
	doesn't sound like much fun, especially if there's an
	expectation of QSL cards....

	Seriously, though -- automatic control of the transceiver (an
	Icom 725) is no problem... it all happens via a serial line
	reachable through the network by any of the console
	processors.  I'm sure some interesting applications for that
	will develop!

				-- wordy

Snapshot of the Bikelab
-----------------------

	I've had a number of questions about the project environment
	here, and before going into this week's feature tech article I
	think a quick description of the lab is in order.

	It's wonderful!  Sun has provided about 1200 square feet of
	windowless lab space in the relatively unpopulated MTV-4, along
	with all necessary hooks to the outside world.  The windowless
	part is not as bad as it sounds -- it keeps me from getting
	seduced by sunny days.  Lighting is a blazing array of
	FLUORESCENTS (inevitably, an acronym:  Fiendish Lights,
	Uniformly Obnoxious Retina-Eating Soporific Cylinders of Evil,
	Noxious, Toxic Substances), though I do have a few normal
	lights to soften things -- like now, when I'm bathed in the
	glow of a SPARCstation 1+ at 3 A.M., trying to push buttons in
	the right order while listening to jazz.

	The computer room is a cubicle in the corner, with three
	systems -- the SPARC, a Mac SE/30, and a generic 386 DOS
	machine.  Fortunately, the chair has wheels -- I use all three
	machines daily and am wearing a delta-wye-shaped path in the
	carpet.  A folding futon stashed under one of the worksurfaces
	gives me a break now and then.

	Next to the office is the machine shop, dominated by Cecil
	(Cecil be da' Mill).  This is a classic 1960 Rockwell knee-type
	milling machine I bought via misc.for-sale, and next to it are
	a grinder/sander, vise, and the other tools of a basic
	beginning machinist's shop.  I try to keep metal bits from
	sailing over the partition to mingle with the electronic ones...

	Along one long wall of the lab proper are four lab benches,
	astrewn with all the usual clutter of hardware hackerdom.  Test
	equipment -- scope, distortion analyzer, SCSI bus analyzer,
	power supplies, and the like -- is scattered around, along with
	various laptops and other development tools.  A variety of
	cabinets and shelving units spill over with inventory and far
	too many magazines, antennas lie about on the floor, a
	camping-gear area overflows one corner, and in the middle of it
	all is a 12-foot BEHEMOTH -- sometimes linked via umbilici with
	the benches.

	It's quite a playground, but I still have tire itch.  31 weeks!

LED Taillights
--------------

	One of the classic concerns about bicycle touring, for lots of
	good reasons, involves lighting and safety.  If you look at the
	situation statistically, it's terrifying:  even if only one in
	every 100,000 drivers runs over you, it's still going to happen
	eventually if you spend a few years on the road.  It thus makes
	sense to make every effort possible to be VISIBLE, and I don't
	mean just screwing on one of those dinky commercial bicycle
	taillights that runs on a few penlight cells.

	My overall lighting system consists of a 4" 20-watt sealed beam
	quartz-halogen fixed to the bike, a Night-Sun dual-beam unit on
	the helmet (with 8 watt flood and 30-watt spot), a yellow 7"
	highway barricade flasher behind the seat, a round bicycle
	taillight, and a pair of 2-section taillights on the trailer to
	provide steady-on, turn signals, and hazard blinkers.  There
	are also reflectors all over the place, an orange safety
	triangle on the back of the trailer, two gaudy flags, a couple
	of utility lights for the operating position, and possibly
	front turn signals if I'm feeling ambitious when I re-do the
	fairing.

	This article is about the taillights... how to make them bright
	and reliable while drawing a minimum amount of power from
	precious and heavy batteries.

	Recent developments in optoelectronics have made this possible
	-- with Hewlett-Packard (408-435-7400; Mark Hodapp), Stanley,
	and Ledtronics offering high-brightness LEDs with intensities
	ranging from 3 to 15 candela at 20 mA.  Viewing angle is
	relatively narrow (typically 7 degrees between half-intensity
	points), but otherwise they behave like any other LED, dropping
	about 2 volts and getting brighter for a given voltage as the
	ambient temperature drops.

	Many automakers, including Nissan, are using these for
	taillight and high-mounted stop light (CHMSL) assemblies -- for
	good reason.  Basically, why start with a lot of radiation
	(heat) that happens to include some visible light, then throw
	away most of the visible stuff to get red?  A typical single
	taillight bulb, like the GE 1816 I used for 16,000 miles, draws
	about 330 mA; a brighter LED cluster draws 50 mA.  The choice
	is obvious.

	BEHEMOTH now carries three LED taillight assemblies.  The
	simplest one is on the back of the RUMP (the fiberglass
	enclosure behind the seat) -- two parallel chains of 7 LEDs
	each, packaged on perfboard in a 2.5" diameter Peterson marker
	light assembly from an auto parts store (I just clipped out the
	original incandescent mounting hardware).  Ten of the LEDs aim
	straight out through the lens; four aim sideways to increase
	visibility from wide angles.  The fresnel-like lens adds enough
	dispersion to yield a very satisfying and bright light.

	The trailer lights are a bit more complicated, and are built
	into Peterson PM-13812 clearance lights, designed for two
	bulbs.  Each .7X1.4" perfboard cluster of 14 LEDs (top steady,
	bottom flash) is fixed to the body by Panduit foam mounting
	tape and a little spacer of lexan Thermoclear (very light
	double-wall glazing), and four wires are routed through the
	trailer wall.  A clean mounting to the curved trailer surface
	was achieved with a gasket of half-inch Poron cellular
	urethane, belt-sanded to shape.

	Electrically, we now have two LED clusters (each consisting of
	2 parallel chains of 7 junctions, totaling 50 mA) in each
	trailer taillight, plus the one on the bike.  Now what?
	Hooking them directly to a lead-acid battery bus would be a
	disaster -- voltage varies all over the map with temperature
	and charge conditions.

	The answer is a small controller board.  A major component is a
	little DC-to-DC converter (in this case, an adjustable-output
	"DC Battery Adapter" made for the laptop market by Product R&D
	at 805-546-9713).  I set this to about 13.25 volts, which
	remains constant over an input voltage range of 10-15V.  It is
	turned on via 1N5817 schottky diode switching whenever any
	light switch is activated that calls for LEDs (trailer tail,
	bike tail, hazard blinkers, or either turn signal).

	In the case of steady-on lights, that's all that happens:  DPST
	light switches source +12 to the supply and ground to the
	associated LED cluster.  But any of the three blink conditions
	power up another part of the board -- a 7555 CMOS timer with
	steering logic to let turn signals override blinkers.  This is
	set to about 1 second with a 50% duty cycle, and yields a nice
	stable flash, switching ground to the appropriate LED clusters
	via IRFD113 N-channel power MOSFETs in mini-DIP packages.  When
	a turn signal is active, the flash signal is also passed to a
	piezoelectric beeper.  (All electronic parts were from Halted
	Specialties in Santa Clara -- 408-732-1573).

	This circuit was a handy place to control the yellow barricade
	flasher, as well.  Originally, this light was a product from
	Bicycle Lighting Systems of Falls Church, VA (though everyone
	seems convinced I stole it from a construction project
	somewhere along the way -- I look like a roving hole in the
	road), and it came with a little 2-transistor oscillator
	board.  It worked pretty well, but is old, corroded, and
	generally un-hackable -- so the bulb is now driven by the
	opposite phase of my 7555 timer, giving the whole system a
	nicely coordinated look.

	Overall efficiency is excellent.  The CMOS is basically free,
	and the DC-to-DC converter costs about 260 milliwatts in
	exchange for about 1.2 watts to a pair of LED clusters.  Not
	perfect, but still well below the wasted power in the
	incandescent units (about 8 watts per pair).  In other words,
	we're getting brighter light, better aesthetics, a crisper
	blink, and much higher reliability for about 1/6 the power.
	Such a deal...

				* * *

	That's it for this week -- I'm trying to keep the length of
	these reports under control.  This week I'm off to Novato to
	pick up a printed-circuit-board milling machine from Instant
	Board Circuits, meaning quick-and-hopefully-easy prototypes

         Cheers from the Bike Lab!

		Steven K. Roberts 
		Nomadic Research Labs 
		P.O. Box 2390 
		Santa Cruz, CA 95063

		wordy@bikelab.Sun.com 
		GEnie, MCI, or AOL:  wordy

