Hi all, I just ordered the ir recievers and detectors that the nerdkits guys recommended on the theremin project. But I don't know if I should use a 9v battery or my 5volt, 1.5 amp power supply so I wont blow the transistor.

-missle3944

It's not voltage that blows things (normally) it is current so use recommended current limiting resistors.

Voltage gets blamed but higher voltage generally just gives you more ampacity to blow things.

Ralph

Hi Ralphxyz,

I am not worried about the voltage but I am worried about the current. I am afraid that the current from the power supply (1.5amps) will blow the transistor.

I have all of the correct resistors too. But I am confused if i can use my own supply or a 9vlt battery?

Hey Missle3944, Just because you power supply is rated at 1.5 amps does not mean that 1.5 amps current will be goign through the circuit. That just means your powersupply can suplly a maximum of 1.5 amps So just use the correct current limiting resistors and you will be fine.

To Find out what value resistors to use:

    USe the formula V=IR
    R=V/I.
    So plug in the Voltage rating for the led, and the current it consumes, that will give you the appropriate resistor values.

Finally, I got it to work! Thanks