User talk:Daveb

Dave Brown playing for a while:)

Project in slow progress

Project	Status	Notes
Reconfigurable sailing proa	mostly inactive, built small bits	Rob Denny at http://www.harryproa.com has some interesting things to say about Proas and how they could be the basis for a cheap, high performance, spacious sailing cruising boat. Perhaps the ideal cruising boat :). I want to explore the sailing characteristics in a model.
LED lights and lenses for my bike	active	http://pilom.com/BicycleElectronics/DynamoCircuits.htm explains the matching of LEDs to bike generators. I plan to have several strings of LEDs with different beam angles and aiming points - and the appropriate string of LEDs turned on for the current bike speed. Success criteria: generate some light at low speed generate more light at high speed get it too work don't break the bank
Visible surge arrestor	project	I want to know when power surges happen, and if possible stop them cheaply and quickly. Project:Surge Arrestor
Low viscosity blood	thoughts	I have some more reading to do; but am intrigued by http://customers.hbci.com/~wenonah/new/mcdaniel.htm and http://en.wikipedia.org/wiki/Integrated_Pulmonary_Index
Quiet boxed PCs	project	I want to run more than one PC, and the droning gets to me :( Project: Quiet Boxed PCs

Project Ideas

Project	Status	Notes
Power efficient raid	idea	Data needs to be written to multiple drives; so a single head-crash does not wipe it out. However, it could be staged to disks sequentially, remaining in memory until it has been written on the 2nd (or n'th) drive. The drives could be spun up more rarely, to simply update the file-store. Perhaps it can be done using two or more file systems and unionfs; with the data eventually residing on a spinning disk, but initially being saved on ssd. The spinning disk using btrfs to make a sequence of stable snapshots from changes preserved on the ssd. Maybe btrfs offers this sort of thing directly?
Make solar cell?	idea	Link http://www.freewebs.com/acselectronics/TiO2solar.html
Safe by design nuclear	meme	2 hour promo
bike trailer	sketches on envelopes	to carry standard building 2.44 x 1.22 M sheets, 2up kayak, etc. Considering extending the bike rack so the trailer can be carried inverted over the rack; wheel mounts that can be pivoted to vary the trailers wheelbase narrow for storage on bike wider for normal use extra wide to control the windage of a building sheet
tricycle	just a thought	Means of getting around...
hack caliphers	seen in sparkfun comments	Member #333257 If you measure current, you will see that the power off state draws 90% of the current of the power on state. For some reason, all electronic calipers seem to be this way- power off is actually display (only) off. THIS is why the batteries go bad quickly. I just open the caliper case, cut the battery trace (which one doesn’t matter), drill two holes to allow the fine (wire wrap) wire to come out the top to a micro-miniature slide switch glued to the top. I always turn the switch off, rather than press some caliper “off” button, and find that a button cell lasts for many years. I would attach a picture if Sparkfun allowed, but it doesn’t. Caliper thickness is unchanged, and the outline is very nearly unchanged.
temperature controller	plan	to control cooker for soldering SMD. ssr to control power to heating plate type k thermocouple to measure temperature attiny 84a dip usb/serial converter to talk to netbook solder-less breadboard with banana-sockets to link 2 through 4

Crazy Ideas

Project

Status

Notes

prime number generator

thought

Invert the sieve of Aristophanes, so the data structure holds primes and the next multiple of each prime. Keep the data-structure sorted by the next multiple. When a gap occurs between the current nearest multiple and the next nearest the gap contains prime number(s).

The algorithm requires sorting subsequent multiples into place. If N is the number of discovered primes N, and the size of the primes is S; then the memory used is O(N*S) and the CPU time used is O(S*N*N).

Other thoughts:

use wheel factorisation of the first M primes to compactly and efficiently represent the impact of these first M primes, where M is chosen so the product of these primes fit in a machine word, and so that the primes less than the product fit in affordable memory.
use interval arithmetic to keep track of the intermediate numbers.
can it be fitted to hardware?

factorisation

thought

By trial division using list of known primes; is exceedingly slow for large numbers; the number of potential factors is O(sqrt(N)) - if N is more than 100 bits that is a big number. However, can knowledge of the factors be used to restrict the search space usefully? What are the constraints on the factors imposed by PGP for example

Dead Ideas

Project	Status	Notes
mirrored coils	reinventing the wheel; already exists as a Common mode choke	wind two coils on the same core, one left hand the other right hand and link them together. I think they should act as a filter of some sort, because the emf generated by the first travels faster than the electrons and reinforces the current in the other coil, smoothing out the edges of each pulse. The filter frequency being related to the speed of light and electrons in copper and the coil winding length. Maybe there would be less energy lost in the filter? I need to learn some maths so I can understand the wiki explanation.

Completed projects

Project	Status	Notes
Lowered Desk	complete	Comfort requires a good desk:). Project:Lowered Desk

Project Status

See Speed Adjustable Bike Light

Parts Shopping

GDT 420v surge arrestor for 240v (if my calculations are right)

wire to board screw connectors 300V 20A

Electrolytic Cap 50v, 2200uF, 8k hours lifetime, 3A ripple current, 23mOhm inductance, ?ESR.