have used a development board to create a small circuit containing a 12V supply plugged into an analogue development board which contains a 100mA fuse. After this i have attached an oscilloscope across the two inputs to complete the circuit and this created a sine wave image on the scope. When looking at the wave it has a peak voltage of 20V when surely it should be a peak of 12V? to confuse me even more when measured with a digital multimeter a reading of 14.8V was achieved. The teacher expected the readings to vary but i cannot provide an explanation as to why? been stumping me for days!
Any reasons for why my readings are like this it would be a terrific help!
What kind of circuit is it? A power supply from AC to DC? If an switching inductive load is switched on/off the overvoltage can be twice as much as the bvoltage on the inductance is.
thats great thanks. Just a final part to that, why is the wave showing a peak amplitude of 20V and a RMS value of 14.85 when the supply from the wall is a 12 volt adapter? or is that a potential mistake on my part in reading data etc!
A 12VAC transformer has an output of 12VAC only when it has its rated load. Its voltage is higher without a load or with a light load because its windings have resistance that reduces the voltage when it has a load.
The RMS voltage is something like an average since the signal swings from zero to peak.