User talk:Daveb: Difference between revisions
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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. | 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. | ||
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|'''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: | |||
memory use is O(N*S) | |||
cpu use is O(S*N*N) | |||
Other ideas: | |||
* 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? | |||
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==Dumb Ideas== | ==Dumb Ideas== | ||
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Revision as of 10:51, 6 October 2012
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:
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| 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 |
| Lowered Desk | project | Comfort requires a good desk:). Project:Lowered Desk |
Project Ideas
| 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
|
| 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. |
| 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: memory use is O(N*S) cpu use is O(S*N*N) Other ideas:
|
Dumb Ideas
| 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. |
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.
