Changing HIGH voltage value of digital pins

Hello,

I am working on a project that involves controlling a bunch of different pneumatic valves. The state of each valve is controlled by a DC signal: 6.0 volts means the valve is open, 0 volts means it is closed. I would like to build a control system to interface with my computer using a prefab Arduino and the digital pins are almost perfect for the task...the only problem is that the voltage they provide when set to output HIGH is 5.0 volts. The specs on these solenoid valves cite 5.4 volts as the operating minimum. Is there any clean way of getting these digital pins to puts out 6.0 volts instead of 5.0, or should I look for an alternative solution? I could build some external circuitry which uses the digital signal to switch a 6.0 volt circuit, but this adds more complexity than is justified by the project...the point is 5 volts is so close to 6 that it would be nice to just get the virgin Arduino working.

Any thoughts would be greatly appreciated.

Thanks, Josh

You're probably going to run into trouble on two fronts: 5V being too low a voltage, and the valve demanding too much current. You can't draw too much current directly out of an Arduino pin, and the more current you draw, the lower the voltage goes (it only outputs near 5V at 0 current).

If you point us to the datasheet for your valve perhaps we can look at it more closely, but my guess is you'll be needing some external hardware.

-- The Rugged Circuits Yellowjacket: 802.11 WiFi module with ATmega328P microcontroller, only 1.6" x 1.2", bootloader

Short answer is no; you'll need additional circuitry (a ULN2003 or similar driver would be workable - depending on current needs). It really wouldn't add that much more complexity or cost to add a driver IC to the design - likely you'd spend as much for an alternate solution.

Hello,

Thanks for the very quick replies, guys!

I am inexperienced with all of this stuff...I am just roughing things using my physics training. This ULN2003 device seems like just the thing, actually. I am looking up the specs now and it should work well - my current needs are quite small: .1A per valve.

Josh

First off 1A is not a small current it is quite large. Next you can't switch that much from UNL2003. Each channel can switch up to half an amp, but you have a limit of about 650mA being on at any one time.

get a transistor that can handle > 1 amp. power it with 6 volts and use PMW from pins to control it

Grumpy_Mike: First off 1A is not a small current it is quite large. Next you can't switch that much from UNL2003. Each channel can switch up to half an amp, but you have a limit of about 650mA being on at any one time.

That was 0.1 amp