Hey guys hope that im putting this into the right catagory. I’m working on a project that needs to fire 8 relays (on/off and then one right after the other) 3 times as fast as i can. Can the Arduino handle this?
Sure. But it depends on the relays you plan to use if the Arduino can handle that without extra transistors and resistors. You will need a diode whenever you are using coils like those in relays.
i will use the 8 channel relay board that has the solid relays thats for the arduino. The max voltage is shooting for is 18vdc and the relays can handle 240v so i should be good there.
Here is the board http://www.amazon.com/gp/product/B006J4G45G/ref=s9_simh_gw_p147_d0_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-3&pf_rd_r=1Q630VRD12BW29C7RJPR&pf_rd_t=101&pf_rd_p=470938811&pf_rd_i=507846
This is not a relay, it is a complete board. Therefore you will be able to use this for what you asked.
However, don't assume you can use a relay that can switch an AC at a certain rate, you can switch the same in DC. It then is about the maximum current that can be switched, which will be lower on DC as it is on AC for most relays. So check the current you will be switching and look up the capabilities in the datasheet of those omron relays (it's not printed on it).
Actually those kind of solid state relays can't be used at all for DC voltage switching as the internal switching element used are thyristor based (back to back SCRs or a Triac) which can only be turned on by the trigger pulse but rely on the load AC current passing through zero (every 8.333 millisec at 60Hz power) to turn off. So if used with a DC load you could turn it on via program control but would not be able to turn a channel off without turning off the DC source power.
Solid State Relay Module Load voltage range: 75 to 264VAC (50/60Hz); Load current: 0.1 to 2 AMP
A true relay module would be more suitable for your DC circuit switching:
If you are looking to switch 18VDC fast and frequently, then I suggest you use power mosfets instead of relays. What is the load that you will be switching?