| 39 | | **Exercise**: use the IRL3715Z N-FET transistor in your kit to allow your arduino to control the flow of electricity through a motor. Turn the motor on or off in response to a switch or to your ultrasonic controller. Use a protection diode (also in your kit) to prevent the back EMF from the motor from destroying the transistor (and potentially you Arduino). You can use the micro-motors provided (see a mentor if you don't have one) or you can use one of the gear-motors from the mini-bot kits (also ask a mentor). The first step in working with any electronic component is to review its [http://www.irf.com/product-info/datasheets/data/irl3715z.pdf datasheet]. The datasheet will give you all of the component's specifications and limits and will often give you examples of how to use it. The IRL3175Z datasheet tells you that it turns on when the voltage between the gate and source terminals is above 4.5 volts (our Arduino uses 5v), that the absolute maximum voltage that can flow between the source and drain (to the motor) is 20v and above that, the device will be damaged. It also tells you that the maximum resistance between the source and drain pins when the transistor is 'on' is 11 milli-ohms (very low), so if you used this transistor to switch 10A (a lot of current) to a motor, it would drop at most 10A * 0.011ohms = 0.11 volts and dissipate 0.11 volts * 10A = 1.1W as heat which is quite manageable. With a heat sink (metal fins attached to the transistor to give it more surface area for heat transfer), it can switch as much as 50A at room temperature. You can learn more about MOSFETs [https://www.youtube.com/watch?v=GrvvkYTW_0k here] how to use MOSFETs for motor control [https://www.youtube.com/watch?v=3tHIXPoKPNc here]. |
| | 39 | **Exercise**: use the IRL3715Z N-FET transistor in your kit to allow your arduino to control the flow of electricity through a motor. Turn the motor on or off in response to a switch or to your ultrasonic controller. Use a protection diode (also in your kit) to prevent the back EMF from the motor from destroying the transistor (and potentially you Arduino). You can use the micro-motors provided (see a mentor if you don't have one) or you can use one of the gear-motors from the mini-bot kits (also ask a mentor). The first step in working with any electronic component is to review its [http://www.irf.com/product-info/datasheets/data/irl3715z.pdf datasheet]. The datasheet will give you all of the component's specifications and limits and will often give you examples of how to use it. The IRL3175Z datasheet tells you that it turns on when the voltage between the gate and source terminals is above 4.5 volts (our Arduino uses 5v), that the absolute maximum voltage that can flow between the source and drain (to the motor) is 20v and above that, the device will be damaged. It also tells you that the maximum resistance between the source and drain pins when the transistor is 'on' is 11 milli-ohms (very low), so if you used this transistor to switch 10A (a lot of current) to a motor, it would drop at most 10A * 0.011ohms = 0.11 volts and dissipate 0.11 volts * 10A = 1.1W as heat which is quite manageable. With a heat sink (metal fins attached to the transistor to give it more surface area for heat transfer), it can switch as much as 50A at room temperature. You can learn more about MOSFETs [https://www.youtube.com/watch?v=GrvvkYTW_0k here] how to use MOSFETs for motor control [https://www.youtube.com/watch?v=3tHIXPoKPNc here]. This [https://www.youtube.com/watch?v=I1h-HZmIJ4E video tutorial] shows an N-Channel MOSFET being used to turn a large motor on and off and includes a good deal of information about MOSFETs and how they work. |
