Are 2 watt resistors interchangeable with lower wattage?

Team Toothpaste · Joined: May 06, 2010 Posts: 25 Location: London

Hey all, I'm currently working on a little op-amp project using a 741 run on 9v batteries. When buying some 1M resistors I accidentally bought some enormous 2W ones. Will these work o.k in the circuit?

slacker · Posted: Tue Apr 26, 2011 12:21 pm Post subject:

Yeah they'll work fine.

Team Toothpaste · Joined: May 06, 2010 Posts: 25 Location: London

thanks slacker!

bubzy · Posted: Tue Apr 26, 2011 11:45 pm Post subject:

The wattage of a resistor is based on the amount of heat it can dissipate, as slacker has rightly said you can replace a small wattage resistor with a larger one, but on the other hand, you cannot replace a 2w resistor with a 1/4w resistor as the 1/4w resistor just cannot dissipate enough heat and will burn out releasing all the important magic smoke.

i know your question has already been answered, but i find that understanding something is more valuable than being told the answer Smile

Team Toothpaste · Joined: May 06, 2010 Posts: 25 Location: London

Thanks bubzy, yea I had a feeling that replacing a high wattage with a lower one would be a bad idea, just wanted to double check about the other way around though. Didn't seem like it would be dangerous but I wondered if it might simply not work. Don't think I'll be building any circuits that require a high wattage for a long time, I'm happy with batteries, and not getting electrocuted for now. Very Happy