I have 3 dozen 5mw laserpoints. They each draw 3v. I want to turn them all on and off in certain sequences. I've done some basic sketches before but I have no idea how to set up the power for multiple things. I want the hardware to be as simple as possible. So I think that leads me to pre made H-bridge modules? Or BS170 MOSFETs ? If someone could be so kind as to draw me the circuit that would be most helpful in getting me started. Will I need a mega since I will have a total of 108 volts running when they are all on? also, I'm using the lasers with it's control board from the laserpointer. I'm planning to solder a wire on the spring and a wire to the other terminal on the laser board for each laser. The button of the laser pointers will be stuck in the on position. Thank you!
Hi,
Welcome to the forum.
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http://forum.arduino.cc/index.php/topic,148850.0.html
How much current is needed for the laser units?
I think you need to learn some basic electronics.
Current flows and is measured in Amps, Voltage is potential difference.
108V indicates you are going to connect them all in series?
How are you going to control them individually.
Link to data/spec of the laser unit please.
Can you tell us your electronics, programming, arduino, hardware experience?
Thanks.. Tom... 
Will I need a mega since I will have a total of 108 volts running when they are all on?
It is hard to get more things wrong in a sentence than that.
- the voltage will not add up to 108V, you power the devices from the voltage it needs and wire them in parallel.
- why is this elevated by a Mega?
I think crawling before flying would be a good idea. Get some basic knowledge first then you can ask sensible questions.
here are the laser units. http://www.ebay.com/itm/201570864314
I will wire them in parallel. I need to control them individually. saying 108v was a mistake. The lasers currently run on 2 x AAA.
Ive done software programming all my life and have built very basic arudino projects.
If you want to control each individual laser, you will need a switch for that laser capable of carrying the required current. You can buy ICs that contain arrays of transistor switches.
What is the required current for one laser module in mA?
So I think that leads me to pre made H-bridge modules? Or BS170 MOSFETs ? If someone could be so kind as to draw me the circuit that would be most helpful in getting me started.
If you have laser pointers, they will already have a power supply built-in* and you can switch them on & off with a transistor, MOSFET, or relay. A relay is an electrically-controlled switch, so if you have an unknown circuit and you want to duplicate the function of a manual switch, a regular-old electro-mechanical relay is the "safest" solution. (Relays with the Arduino require a driver circuit so you might want to get a relay board with the driver built-in.)
But if you need to switch them on & off quickly and "cleanly", you'll have to do some experiments because the characteristics of an unknown-random power supply are... unknown. (And, relays are not as fast as transistors/MOSFETs.)
- Laser diode power supplies are tricky so I recommend that you don't try to build one yourself. [u]Here[/u] is some information.
I've measured similar laser modules, and they take about 400mA at 3v each.
to drive 36 you'll need a supply of 36 x 0.4 or 14.4 amperes at 3v. That's a big psu.
And to drive each one individually I suggest logic level MOSFETs.
You will need either a small Arduino with port expanders, or a large one - eg mega or due - to drive that number of outputs.
Any help?
regards
Allan
Also, when you dig into the devices to modify them, do so delicately. I buy these exact pointers for use in class. They aren't made very well, and tend to break easily.
allanhurst:
I've measured similar laser modules, and they take about 400mA at 3v each.
How can a 5mW laserpointer consume the above 1.2W ?
They're very inefficient?
Correct!
Inefficient and complex! Green lasers are a three stage optical device. It starts with an IR diode laser at about 810nm, which pumps a niodymium:yttrium orthovanadate solid state laser, which in turn is frequency doubled by a potassium titanylphosphate crystal to the visible green (532nm) beam that you see.
All these non-linear optical transitions soak up the energy.
OP wants to sequence the LEDs, so parallel as requested is out.
I'd start with some variation of 74595 / TPIC 595 shift registers in a chain, some 2N7000 if needed, and power supply.
Current sink is distributed (at most with 8 LEDs per driver), so powering may be easier. Still need the source total TBD later.
Code is then relatively trivial with one byte of shadow storage for each 8 LEDs... push them out whenever you want a change.
so parallel as requested is out.
Given you can only wire things in seriese or parallel, and you can't use seriese because of the voltage required and the fact you want individuals control, parallel is not at all out.
Parallel = a boatload of wiring!
What's the issue of serial and voltage? Run an overvoltage supply bus, and regulate down locally for each shift / laser cluster.
What's the issue of serial and voltage
I said seriese not serial. Given the number of posts you have I think you are misunderstanding what is being asked.
- good catch!
Autocorrect changed series into serial !
Im still not sure why there's a benefit to wire & drive so many devices in parallel unless really needed.
lastchancename:
- good catch!
Autocorrect changed series into serial !Im still not sure why there's a benefit to wire & drive so many devices in parallel unless really needed.
Parallel because the OP wants to have individual control.
Tom...
That's why (back in reply #12), i suggested serial. (not series!)
Single over-spec power rail, daisy-chained shift registers.
Still seems like the easy way out to me, unless i'm missing a chunk of the requirements.