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Author Topic: adapter usb 5v ok, adapter 9v causes problems  (Read 577 times)
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Hello,

When i connect my arduino by usb to my pc or to the iphone adapter (5v 1a) my arduino works as aspected. But when i use a adapter with 9v 1200ma i have some problems: a piezo buzzer sounds bad and when i put a pin high for opening a transistor the arduino resets.

With the 5v adapter i measured about 4v from the pin which is connected to the piezo buzzer, with the 9v adapter i measured about 3,5.

Does anybody what i'm doing wrong?

Regards,
Thomas
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Which Arduino board are you using ?

It is probably a heat problem of the voltage regulator.
The voltage regulator on the Arduino board makes 5V. If the input is 9V, the 9-5 = 4V is turned into heat.

Solution:
(1) Don't use the voltage regulator of the Arduino to power a lot of things, only a few leds and sensors. Use a seperate power supply for the components.
(2) Lower the input voltage to 7V or 7.5V.
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To me, it sounds like excessive ripple is getting through. Can you try a different adapter?
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Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

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