Search found 1191 matches

by MichaelN
Sat Feb 01, 2014 4:35 pm
Forum: Arduino
Topic: Power supply interference causing glitches?
Replies: 6
Views: 1222

Re: Power supply interference causing glitches?

We really need to know more about the sensors, and see a wiring diagram / schematic showing how everything is connected. These things can be subtle. Voltage spikes / dips on the power input may be causing problems, or it could be that adding the power connection allows noise to enter on the sensor i...
by MichaelN
Sat Feb 01, 2014 4:24 pm
Forum: GPS
Topic: Stolen bikes
Replies: 4
Views: 2150

Re: Stolen bikes

Definitely feasible - there are a number of products that do what you're after already (eg SpyBike, BikeSpike). If you want something cheaper, there are generic GPS tracking devices that you may be able to use eg: http://dx.com/p/portable-gps-gsm-gprs-personnel-tracker-silvery-grey-199123 If you rea...
by MichaelN
Sun Jan 05, 2014 7:46 am
Forum: SparkFun Product Questions
Topic: How do I power my BED?
Replies: 4
Views: 604

Re: How do I power my BED?

How about linking to the product you're talking about (or at least providing more info than "BED")?
by MichaelN
Tue Jun 04, 2013 8:06 pm
Forum: Arduino
Topic: Powering an Arduino in my car, full time?
Replies: 3
Views: 2856

Re: Powering an Arduino in my car, full time?

You probably want a switchmode step-down regulator, to minimise battery drain & power dissipation, unless you’re only drawing a small amount of current (code optimisation may mean that the micro spends most of its time in a reduced power state when the car’s ignition is off). Look at something like ...
by MichaelN
Thu May 23, 2013 5:12 pm
Forum: SparkFun Product Questions
Topic: RTC with Supercapacitor Recharge
Replies: 40
Views: 10601

Re: RTC with Supercapacitor Recharge

viskr wrote:You will need it to limit the current draw from the USB port, if you draw more than 500 mA the PC will disable the port...
In theory they should, but most devices will let you draw MUCH more than 500mA before they cut you off. Hence the proliferation of those ridiculous USB drink warmers etc...
by MichaelN
Wed May 15, 2013 7:24 pm
Forum: SparkFun Product Questions
Topic: Rotatory potentiometer reliability
Replies: 12
Views: 1337

Re: Rotatory potentiometer reliability

Note many of these I've seen don't use a potentiometer, but instead use a photo emitter/detector pair and a piece of plastic with an optical gradient from clear to opaque that moves through the gap between the emitter & detector Well this is interesting,i've already made the order for some potentio...
by MichaelN
Mon May 13, 2013 8:15 pm
Forum: PIC Microcontrollers - Software and Hardware
Topic: Microcontroller current draw is unusual?
Replies: 2
Views: 711

Re: Microcontroller current draw is unusual?

Have you read the datasheet? I assume the Supply Monitor is doing exactly what you've configured it to do, ie, hold the chip in reset until the supply voltage exceeds 3V! At this point, you'd expect the chip to draw more power.

http://www.atmel.com/Images/doc11011.pdf
by MichaelN
Mon May 13, 2013 9:08 am
Forum: SparkFun Product Questions
Topic: Rotatory potentiometer reliability
Replies: 12
Views: 1337

Re: Rotatory potentiometer reliability

@MichaelN: i was initially looking for an encoder,the problem is that they usually have few readings foreach turn (like 12-25) so,to get a good value range i'll have to use gear in order to increase the rotation of the encoder,and i'd like to avoid it. There are plenty of encoders available with th...
by MichaelN
Sun May 12, 2013 6:40 pm
Forum: SparkFun Product Questions
Topic: Rotatory potentiometer reliability
Replies: 12
Views: 1337

Re: Rotatory potentiometer reliability

Why not use a rotary encoder instead? Especially if you use an optical type, they'll essentially last forever, with no degradation.

If you do use a pot, look for a "conductive plastic" or cermet type - far more reliable than cheap carbon-film types.
by MichaelN
Wed May 08, 2013 8:19 pm
Forum: Arduino
Topic: EL wire jumpsuit project - where to start?
Replies: 4
Views: 675

Re: EL wire jumpsuit project - where to start?

...I explain what i want to build, you help me with the schematics and code, i put it together myself...i just need someone to design the schematics and code for me so i can build the thing because i generally learn by doing. any takers? I think you’ll find that people around here will be happy to ...
by MichaelN
Sun May 05, 2013 9:58 pm
Forum: SparkFun Product Questions
Topic: Cooling a safe w/ a Termoelectric Cooler
Replies: 5
Views: 730

Re: Cooling a safe w/ a Termoelectric Cooler

While other posters have a good point about it not being the best option, it certainly is feasible. There are plenty of small PCs that consume much less than 50W. Peltier coolers are not very efficient - at best, they only shift about as much heat as the power they consume. That is, if you have a 50...
by MichaelN
Sun May 05, 2013 6:18 pm
Forum: SparkFun Product Questions
Topic: on/off 220v Fan driven by arduino
Replies: 5
Views: 2105

Re: on/off 220v Fan driven by arduino

That first relay isn’t suitable – as per the datasheet, it needs at least 9VDC to turn on (this is the “pickup voltage”). The 5VDC min rating is for the LOAD (5VDC @ 10mA). Perhaps counter-intuitively, switches and relays often have MINIMUM as well as maximum load ratings. The second link would work...
by MichaelN
Tue Apr 30, 2013 7:38 am
Forum: SparkFun Product Questions
Topic: schematic check
Replies: 8
Views: 809

Re: schematic check

Hami wrote:Which LDOs are u using? May you recommend a LDO?
I've used LP2985 for quite a few years, but there are lots of others (eg MIC5203).
by MichaelN
Mon Apr 29, 2013 5:22 pm
Forum: SparkFun Product Questions
Topic: newbie making a 12 volt powered usb hub
Replies: 2
Views: 562

Re: newbie making a 12 volt powered usb hub

You could connect a 5V supply to the positive and negative of the input USB cable, but there are a couple of problems: - Since the hub cannot talk to the host (normally a PC), it might not allow the phones to draw any current - Even if it does allow the phones to draw current, as a self-powered USB ...
by MichaelN
Sun Apr 28, 2013 5:00 pm
Forum: SparkFun Product Questions
Topic: schematic check
Replies: 8
Views: 809

Re: schematic check

Those regulators are not designed to be used with ceramic output capacitors, which have very low ESR and can lead to instability. You can either use tantalum capacitors, or add small resistors in series with ceramic capacitors. Personally, I only use regulators designed for ceramic caps. The datashe...