Can the MD24 be used to drive motors, solenoids, etc?

[John]

A common question is whether or not the MD24 can be used to control solenoids, motors, or other DC loads. The answer is yes--however, most motors or solenoids will exceed the current capacity of the MD24 output (and may require a voltage greater than 5V).

A nice article showing how to control an arbitrary DC load using a 5V output (like from the MD24) and an NPN drive transistor is here:

http://www.kpsec.freeuk.com/trancirc.htm#ic

Note: the page refers to "IC output" which is what the MD24 outputs are.

NPN transistors for this purpose are very common & inexpensive. A common type are parts TIP120/TIP121/TIP122.

If you'd rather not build your own transistor drive circuit, you can use the MSA-T, which has the drive transistors (TIP122) built-in.

[John]

Here's a diagram showing how an MD24 can be used to control a DC motor, solenoid, or relay. The diagram assumes that the motor/solenoid/relay can operate from 9VDC.

Instead of a coil/motor, this circuit could also drive a high-brightness LED. (A bright LED might draw too much current for the MD24 to drive directly.) Of course, add a current limiting resister in series with the LED.

[John]

If the coil requires a different power voltage than the MD24, or if a separate coil supply is needed for any other reason, the diagram looks like the one below.

Of course, the specs of the NPN transistor and protection diode must be considered in regard to the coil current and coil supply voltage.