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961  Using Arduino / General Electronics / Re: Controlling a 5v relay, only getting 2.4v? on: June 28, 2013, 08:05:33 pm
Slightly more, not major.

Attached drawing.  Is yours set up accordingly?
962  Using Arduino / General Electronics / Re: Suggestion for a standard triac and triac driver ? on: June 27, 2013, 06:01:34 pm
Do you people know of a standard triac able to handle at least 10 amps with a trigger current of no more than 50 mA and a suitable standard triac driver without zero crossing detection for it?

random firing (non-zero) triac driver - MOC3023 (or any MOC302x)
BCR8_ - 8Arms; 30mA gate trigger
963  Using Arduino / Project Guidance / Re: Help a noob keep his dogs from stealing stuff from the dining-room table. on: June 24, 2013, 09:44:03 pm
Was looking for something a little more Arduino/electronics related, but it was still fun!

Like what?

What could possibly work?
1) something they would be averse to by nature
2) something they've been conditioned to associate with punishment (or reward, but not in this instance)
964  Using Arduino / General Electronics / Re: Soldering wire onto MOSFET on: June 24, 2013, 01:32:16 pm
You'll have to solder the wires to a ring terminal, first, and then fasten that to the heatsink.
965  Using Arduino / Motors, Mechanics, and Power / Re: Controling a 3.6V 1.2A Unipolar stepper motor on: June 23, 2013, 06:33:02 pm
$63 !

Forget all that ULN stuff. 
Get some logic-level MOSFETs (IRLZ44, STP40NF10L.)

For motor supply use 3 NiMH batteries (1.2V ea.)
966  Using Arduino / Motors, Mechanics, and Power / Re: Transistor Stepper Motor Driver on: June 23, 2013, 06:20:15 pm
To be practical, you can't do it all with only PNP transistors.
You'll need some NPN transistors, too.

967  Using Arduino / General Electronics / Re: High-side switching or low-side switching? on: June 23, 2013, 11:19:11 am
How about using a FET driver?

> > > When the camera is switched off then change the pinModes of the/any OUTPUT signal lines, as suggested in a similar discussion, to INPUTs (but not as INTERNAL_PULLUP inputs.)

968  Using Arduino / Project Guidance / Re: Using Arduino BT for bike odometer on: June 23, 2013, 11:03:50 am
Does the wiring on the breadboard look ok? I'm really not sure.   

Can't tell without the schematic of what it is you're supposed to have.
Don't forget to add links to any other devices (datasheets) you're using.
One picture showing everything is best: tidy wiring counts (for clarity), avoid having this or that going under a board or out of the shot, and use good lighting (my camera will take pics w/ inadequate lighting and they look fuzzy for it.)
969  Using Arduino / Project Guidance / Re: Using Arduino BT for bike odometer on: June 23, 2013, 09:35:13 am
I haven't seen an "Arduino Bluetooth" like what you have there before.
[It's an official product.]  There's no USB so you upload your sketch via BT or ICSP (or both)?  That's interesting.

I noticed it has screw terminals for power/+VIN and that you're using a dinky "transistor battery".
I'm going to go out on a limb and suggest that it needs a more substantial source, possibly by making your own battery pack or using a NiMH R/C battery.
(As you used "whilst": Maplin 6AA Battery Box, Order Code: HQ01)

I also found this interesting:
Communication between the BT module and the computer can be temperamental. You might want to open the serial monitor a couple of seconds after resetting the board.

[I don't have anything for MP4'ing with.]
970  Using Arduino / Project Guidance / Re: Help a noob keep his dogs from stealing stuff from the dining-room table. on: June 22, 2013, 08:45:52 pm
However, the little piezo chirps didn't impress the dogs at all. What I need is MORE POWER!

Exactly why would that "impress" them?
What's the basis?
Have they been trained (conditioned) to associate piezo chirps with punishment?
971  Using Arduino / Motors, Mechanics, and Power / Re: Question: Zero crossing triac driver on: June 22, 2013, 08:38:47 pm
I am aware.
The OP is asking about zero-crossing triac drivers, though his objective isn't transparent (no offence, void).
As far as SSRs go, I don't know about "most", but "most" available from surplus concerns are zero-cross.

If I wanted to get tricky and trigger only one alternation or something, I'd go full out with a random-type triac driver, that's what they're for.
If all I care about is turning a lamp on/off, it's not important if I miss an alternation before it goes on or if it stays on an alternation after I disable the driver's (DC) input.

Anyway, should a zero-crossing driver get an input tick (indeterminate) in the middle of one alternation, I don't know to a certitude whether the output latches and consequently triggers the triac that it's responsible for, at zero-cross, in the following alternation. 
I think that there would be a pulse-width (noise filtering) minimum for that just the same.

In any event, given a zero-cross triac driver, I would plan to have a solid input enable in anticipation of that zero-cross and hold it there till I required it to go off.

I haven't seen any zero-crossing triac drivers used in conjunction with a zero-cross detector, as in a random trigger, AC phase control situation, as the timing reference isn't required.
972  Using Arduino / Motors, Mechanics, and Power / Re: Can I control these 2 coolers via PWM??? on: June 22, 2013, 05:43:36 pm
They are not "ICs", they are semiconductors - the 2N3904 is an NPN transistor and the 1N4001 is a diode.
Generally speaking, look for an NPN transistor (described as 'general purpose amplifier') with a collector current rating greater than the fan's rated current.
As for the diode, practically any rectifier diode will suffice. there any risks to fry arduino board?

Only if you don't get the wiring right. 

Before you commit, get guidance from your friends here.
973  Using Arduino / Motors, Mechanics, and Power / Re: Question: Zero crossing triac driver on: June 22, 2013, 05:34:36 pm
Typically, I think, a zero-crossing triac driver is for simple on-off stuff.

So, maybe you're asking:
if the input got pulsed, say at line peak (90deg or 270deg), would the driver side sit "armed", as a latch, primed, ready for zero-cross, where it would turn the triac on?  Is that it?

I'm not sure the form of the zero-crossing circuitry (internal).  I haven't used one where half-cycles was an issue.
974  Using Arduino / General Electronics / Re: Npn transistor circuit [Solved] on: June 22, 2013, 12:25:12 pm

The + rail connects to collector
The motor goes between emitter and common ground

No, man, that's what you were doing before.
It should be as in the attached picture, but with the motor in place of fan.
(9V vs 12V, all these being equal, etc)
975  Using Arduino / General Electronics / Re: XBee Powering on through Serial line on: June 22, 2013, 12:21:32 pm
I also have the Arduino control the power going to the Xbee to save power.

How are you doing that?

Porting signals to an unpowered device is generally undesirable.  In this case, some of the XBee circuits are finding Ground through Dout/Din.
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