10. Output Devices

This week we looked at output devices. We were taksed with measuring the power consumption of a output device.

You need to make sure the power supply the current required by the motor, it can be easy to go too large and find it difficult to power it.

Ways to Measure Load

1. Bench supply that has a meter for voltage and a meter for current. Connect it to the load. When you set the voltage it will tell you how much current its drawing.

2. Connect a supply to the load and put a 1ohm resistor going to ground and then measure the voltage going across that say by using a analogue input into a microcontroller. You can then sense the current going through it.

3. Connect a supply to the load. The current through the wire makes a magnetic field. If you have a DC current and put a magnetc field sensor next to it, you can calibrate the strength of the magnetic field and get the current. If you have a AC load thats varying. You can wind a coil around it and the varying magnetic field will induce a current in the coiled wire and then you can sense it.

We went with method one and also used a multimeter to varify the values.

We used the desktop multimeter just above it to comfirm it was drawing 0.114-0.117 Amps.

We also used the handheld multimeter to measure the current.

We then switched it to measure the amount of voltage and the multimeter confirmed the desktop power supply was providing 5v.

You can also see this on the handheld multimeter.