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 by lyndon ¦  Thu Aug 07, 2008 5:40 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Small solenoid? ¦  Replies: 6 ¦  Views: 1529

I have a few Lucas solenoids a bit larger than that (1.5x0.75") and they are pretty strong.

Have you considered winding your own solenoid? For the amount of pull you describe it shouldn't take much.

 by lyndon ¦  Wed Aug 06, 2008 7:02 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Small solenoid? ¦  Replies: 6 ¦  Views: 1529

With such a small throw a servo with a short horn should work. Will also hold at end of travel.

 by lyndon ¦  Wed Aug 06, 2008 1:11 pm ¦  Forum: BatchPCB ¦  Topic: LB SMT Serivces ¦  Replies: 10 ¦  Views: 4636

OK, here's some feedback after I spent way too long on your site trying to figure out what it would cost: - Put some sample pricing ON THE FRONT PAGE. e.g., 20 parts, SMT on 10 boards costs $$$. This at least lets me know if I should look further or you're out of my league. - A link to a spreadsheet...

 by lyndon ¦  Fri Aug 01, 2008 3:26 pm ¦  Forum: Wireless/RF ¦  Topic: how to know my RN-41 works or not ¦  Replies: 11 ¦  Views: 2722

This is how my RN41 is configured: All GND pins to ground (I think there are 6 of them) Vdd to 3.3V CTS looped back to RTS (pins 15, 16) LED on pin 21 with 330ohm resistor to Vdd. Tx & RX to a microcontroller. All other pins N/C At power up the LED blinks quickly then slows down after 1 minute when ...

 by lyndon ¦  Fri Aug 01, 2008 6:30 am ¦  Forum: Wireless/RF ¦  Topic: how to know my RN-41 works or not ¦  Replies: 11 ¦  Views: 2722

Connect an LED to pin 21. It should blink on power up.

 by lyndon ¦  Thu Jul 31, 2008 10:24 am ¦  Forum: SparkFun Product Questions ¦  Topic: nimh battery charger ¦  Replies: 5 ¦  Views: 1707

The reason you shouldn't charge the cells in parallel is really because then it's harder to tell when the cell is fully charged and you should stop charging it. If you can monitor and control the cells individually there's no reason not to do it. There are two relatively simple solutions: 1) trickle...

 by lyndon ¦  Wed Jul 30, 2008 4:52 pm ¦  Forum: SparkFun Product Questions ¦  Topic: very thin mirror glass ¦  Replies: 3 ¦  Views: 1402

Anchor Optics sells Edmund surplus at much lower prices. Here are some thin first surface mirrors:

RN-xx external antenna?

 by lyndon ¦  Wed Jul 30, 2008 4:48 pm ¦  Forum: Wireless/RF ¦  Topic: RN-xx external antenna? ¦  Replies: 0 ¦  Views: 531

Has anyone removed the chip antenna on an RN41 and replaced it with a stub or dipole ant? How did it work? I can't find any reference to this on their site and I'm working on something that will be housed in a metal enclosure so it needs an external antenna. I'm looking at the Sena units with extern...

Soldering RN-41

 by lyndon ¦  Thu Jul 24, 2008 10:21 am ¦  Forum: Wireless/RF ¦  Topic: Soldering RN-41 ¦  Replies: 1 ¦  Views: 916

Any tips on soldering an RN41 to a PCB? I have one connected on a protoboard with point-to-point wiring dead bug style but I just finished laying out a PC board for the design. I'm planning on using the skillet method of SMT reflow with the module. It works fine for smaller components but I"m a bit ...

 by lyndon ¦  Tue Jul 22, 2008 9:47 am ¦  Forum: SparkFun Product Questions ¦  Topic: Wind power for a small MCU board ¦  Replies: 17 ¦  Views: 3102

I'd think that a mechanical device like the windmill would be even less reliable than batteries in that cold. Wires become brittle, need cold-rated lubricants, drifting snow to clog up mechanisms, etc... I looked into low temperature batteries before (I live in Minnesota and it drops to about -25F a...

 by lyndon ¦  Fri Jul 18, 2008 5:48 am ¦  Forum: SparkFun Product Questions ¦  Topic: battery "gas gauge" ¦  Replies: 4 ¦  Views: 2341

As bigglez said, there is no simple, accurate way other than a gas gauge IC and as far as I know, even those aren't very accurate because battery characteristics change over time. A simple, not very accurate way is to monitor the no-load voltage of the battery. Perhaps a comparator set to a voltage ...

 by lyndon ¦  Thu Jul 17, 2008 7:03 pm ¦  Forum: SparkFun Product Questions ¦  Topic: low cost DC water pump ¦  Replies: 39 ¦  Views: 18173

You can find battery powered (DC) aquarium pumps in most pet stores. I have one around here somewhere. Cost is about $10 or so.

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