Control 30 solenoids cheaply

I need to control 30x 25V, 2ohm solenoids from an arduino. (never more than 2-3 at once though, and usually only pulsed for ~100ms) Right now, the best solution I've come up with is just to use 30 BUK9535 (http://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&KeyWords=568-9730-5-ND), however that's also $30 worth of electronics. Is there any cheaper or more bulk way to do it? (I've got the pins, that's not a problem)

Not too bad. Look at AOI516 or AOI518, half the price. 30V max rating might be a little close.

I am just now assembling a board with 32 of them!

Maybe completed pictures tomorrow.
Power for each group of 8 comes from larger screw terminal at the end, wide power traces down the length of the screw terminals on the top & bottom of the board. Top layer left nice & wide for ground return path from the transistors back to the power screw terminal.
Sized for 8A of current, 25V pulses of 12.5A (?) should be okay. Can also add more wire in parallel with the traces.
May have to wire direct to the board too, the Phoenix brand 3.5mm screw terminals are only rated for 10A.
The 5.0mm power connectors from Pololu.com are rated for 16A.

The extra holes in the middle allow for an Uno on standoffs, and the boards may be daisy chained.

Only 2.5W max power? Or is that not something I should be worrying about? 30V would probably cut it, but I've been trying to at least double this sorta stuff, just in case :D

off topic, how much did it cost you to get that board printed?

Where did 2.5W come from? I was thinking 12V, 8A x 4 when I created it, 1 amp per transistor in each string of 8. Designed for long strings of LEDs, like 50 groups of 3 LEDs drawing 20mA each, per screw terminal. Kept fattening the power traces, doubling them up, breaking them apart (hence 4 power inputs) cleaning up the return paths so nothing acted like a fuse, while allowing room in the middle for the pairs of wires to connect up. Gonna be a weighty little board.

10cm x 10cm boards are $20 for 10 plus shipping at iteadstudio, so I have a box of 10 sitting here.

off topic, how much did it cost you to get that board printed?

It's your dime . (it's your thread). It's not off-topic if you're interested in your thread. Ask anything you want . A better question would be how much would he charge you for one of those boards .

2.5W on the AOI516

@raschemmel but designing the things is half the fun!

@raschemmel but designing the things is half the fun!

Why re-invent the wheel. You want to control 30 solenoids and he has a 32-channel Mosfet driver board. That sounds like a perfect match to me.

Ah - but the AOI516 will not dissipate 2.5W. It will dissipate IIRds watts.
As designed for, that’s 1A x 1A * .01 = 10mW.

I don’t have the AOI518 datasheet, the AOI516 is similar tho.

For 12.5A, that’d be 1.56W, and heat sink might be needed if the on times were longer.
100mS on time, maybe not.
I say 12.5A from 25V/2ohm coil if I read your original post correct.
You’ll also need diodes across the coil contacts that can handle that current.

AOI516.pdf (326 KB)

You'll also need diodes across the coil contacts that can handle that current.

I think you mean "across the coil" since solenoids don't have contacts. (unless you meant "across the coil terminals")

Either wording works for me. Got an inductor, get a diode across it.

zacaj:
I need to control 30x 25V, 2ohm solenoids from an arduino. (never more than 2-3 at once though, and usually only pulsed for ~100ms) Right now, the best solution I’ve come up with is just to use 30 BUK9535 (http://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&KeyWords=568-9730-5-ND), however that’s also $30 worth of electronics. Is there any cheaper or more bulk way to do it? (I’ve got the pins, that’s not a problem)

Surface mount MOSFETs in packages like DPAK and D2PAK might be cheaper,
you can get dual MOSFETs in SOIC8 (although I’d worry about those current
peaks in such a small package). You’ll need free-wheel diodes or equivalent and
some consideration of power (perhaps a large capacitor to help supply)