Controlling / driving solenoid valves

dberg

Hello,
I would like to control 8 solenoid valves. They are rated at 28 watts 12vdc so they will draw about 2.33amps each. What is the best choice of driver circuitry for these solenoids? I am using a BS2. Thanks!

Mike Green

Look at Nuts and Volts Column #6 (go to main Parallax webpage, select the Resource tab, then choose the Nuts and Volts Column). It discusses controlling solenoids, relays, and small motors using a Stamp. You could also choose a ready-made solid state relay. There are a number of them made by companies like Crydom and made for voltages and currents on this order. A simple power junction transistor or power MOSFET (with a protective diode) can also do the job as shown in Column #6. The "Industrial Control" tutorial that you can download here (www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/List/1/ProductID/142/Default.aspx?txtSearch=industrial+control&SortField=ProductName%2cProductName) has examples of this including the use of an MOSFET like an IRL510 (not the same as an IRF510) which can easily handle this sort of load.

Post Edited (Mike Green) : 6/2/2008 8:02:39 PM GMT

dberg

The MOSFET solution is much more cost effective for me than the solid state relay. Are you suggesting I use the IRF510?
I really appreciate you help. Thanks!

Mike Green

DO NOT USE THE IRF510. It will not adequately switch on with a 5V input. The IRL510 is a similar device with a lower input threshold typical for logic circuitry. Look at the graphs on the datasheets for the devices for the gate voltage vs. drain current. You'll see that the IRF510 will only provide about 0.5A of drain current with a gate voltage of 4.5V while the IRL510 will provide about 5A with the same gate voltage.