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Topic: Difference between Arduino 5V power and output of 7805 5V power (Read 5298 times) previous topic - next topic


It shows 0.25A @ 20m setting and 0.2 at 200m .... i'm not sure about Ampere setting on multimeter !!! there is 2000u, 20m and 200m really sorry for that but reading site suggested by JimboZA but due to non-electronics field, it takes much time than required....

If the current is unknown you usually you start at 10A and work downwards. The reason is that many meters have 250mA fuses in them which blow and leave you wondering why the meter isn't working. Make sure you've got less than 200mA before you use any scale other than 10A.

So...put the meter on the 10A scale and insert the meter between the resistor and the LED. What does it say?

a) You usually have to swap the 'positive' (red) multimeter lead to another connector on the meter to use the 10A scale (this bypasses the internal fuse).
b) You have to measure amps with the meter in series with the components, eg. between the resistor and LED. Break the connection between them and connect them through the meter.

If the meter says less than 0.2A, swap the red lead back to normal position, switch to 200m scale and read it again. If it reads less than 0.2, switch to 20mA scale, etc.

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)


The capacitors on the Voltage regulator is to stabilise it. The capacitor acts like a reservoir of power, so it takes out small fluctuations in the power. Said shortly it helps the V-reg hold the voltage steady and accurate.

If You want more explanation, read a datasheet for a 78xx regulator.

// Per.

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