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241  Using Arduino / General Electronics / Re: Good quality cheap multimeter on: March 06, 2014, 12:19:37 am
Do yourself a favor, only get a meter that is autoranging.

And I strongly suggest that you do NOT buy any Cen-Tech meters. The last five I bought there were filled with solder balls and bits of wire. Sad, because they used to have some decent cheap DMMs.

I bought a Craftsman meter from Sears a few years ago. It just started malfunctioning, indicating 85Vac on a 120Vac circuit even after replacing the battery. I opened it up to find several capacitors with the heat shrink labels half off and one missing the label entirely. It was NOT inside. Additionally, whomever had trimmed the 10A shunt by half cutting through it had taken a big chunk out of several nearby parts. Several solder balls, way too much solder on the joints.

This was NOT a cheap meter. Very disappointing.
242  Using Arduino / Sensors / Re: battery temp sensing on: March 05, 2014, 01:46:30 am
Figure 3.8.3.

http://en.globtek.com/nimh-battery-safety-notes.php#
243  Using Arduino / Sensors / Re: RPM Sensors on: March 05, 2014, 01:35:53 am
Yes, you can.
244  Using Arduino / General Electronics / Re: PCB question on: March 04, 2014, 04:57:58 pm
Since a schematic is merely a representation of the parts and what they are connected to, and not meant to be an accurate image of exactly how much wire is connected where, no, there is no difference between those.

As for actual circuit placement, it depends.
245  Using Arduino / General Electronics / Re: Power Supply on: March 04, 2014, 02:42:14 pm
If a given power supply using a single diode is rated for, say 9V at 500mA, then yes, it'll put out 9V at 500mA. The current rating is a function of the resistance of the transformer wires and the size of the core.

But for a given transformer and smoothing capacitor, it can put out more current with a 4 diode bridge rectifier. Both because there is only 1/2 the time between charging peaks into the smoothing capacitor, and because the maximum current through the winding resistance is drawn 2x as often to charge the smoothing capacitor and therefore provide power.
246  Using Arduino / Sensors / Re: RPM Sensors on: March 04, 2014, 08:03:26 am
You don't need the gear to be magnetized to use a hall effect sensor. Position a magnet and hall effect sensor so that the path of the magnetic field through the sensor is affected by the position of the teeth.

Maybe like this, or perhaps with the sensor near the teeth and the magnet next to it.



247  Using Arduino / Sensors / Re: The three stages of Promimity on: March 04, 2014, 07:55:48 am
Broadcast at three power levels. Send a code to be picked up on the receiver. If it picks up one, you are at the farthest distance, two, getting closer, three, very close.
248  Using Arduino / Sensors / Re: Vibration ( noise ) from motors. on: March 04, 2014, 07:53:29 am
Are your props balanced?

You attached a docx file, which I think can only be opened by the latest version of Microsoft Office.
249  Using Arduino / Sensors / Re: Simple angle measurement on: March 03, 2014, 06:40:13 pm
So you can't attach anything to the balloon?

If you can, why not a pendulum and optical encoder? Gravity provides the reference, then.
250  Using Arduino / Sensors / Re: Platinum Rtd resolution on: March 03, 2014, 06:37:54 pm
http://datasheets.maximintegrated.com/en/ds/MAX31865.pdf
251  Using Arduino / Sensors / Re: help using analog inputs as an ohm meter on: March 03, 2014, 05:32:18 pm
Schematic? Much more helpful than a pictorial.
252  Using Arduino / Programming Questions / Re: Servos stop working with Delay on: March 03, 2014, 04:34:04 pm
 smiley-red Um... sure, I knew that....
253  Using Arduino / Programming Questions / Re: general c question on: March 03, 2014, 04:33:05 pm
Erp! I screwed up... I meant to type 3/2 = 1.

2/3 does indeed return a value of 0 when using integers.
254  Using Arduino / Sensors / Re: Which type(s) of sensors for a project like this on: March 03, 2014, 04:30:39 pm
If you can find one of the Hot Wheels Radar Guns, you can hack that:

http://www.instructables.com/id/Radar-Gun-Hacked!/

Unfortunately, the price is about $100.

http://www.amazon.com/Mattel-J2358-Hot-Wheels-Radar/dp/B000EHLB0M

For that, you can get a real (cheap) radar gun, too.

http://www.amazon.com/Bushnell-Speedster-III-Radar-Speeds/dp/B00439V84G/ref=pd_sim_sbs_t_2?ie=UTF8&refRID=11R1T6Y0CCND9YTXHSMN
255  Using Arduino / Sensors / Re: help using analog inputs as an ohm meter on: March 03, 2014, 04:25:13 pm
Schematic? Code? Please use code tags, and make your schematic images less than 1000 pixels wide.
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