Nuts and Volts - November 2013

deal only in batteries and they may be able to recycle. Many "big box" stores have recycling available for rechargeable batteries. You just have to ask at places dealing with products that are prone to battery power.

Dean Huster via email

#2 Visit your local Lowe's store. The ones in my area of the East Coast have a recycling bin near the returns desk that takes CFLs and rechargeable batteries. No muss or fuss, just drop them in!

Home Depot also takes them at the customer service desk. I just box them and mark the box 'Battery Recycling' and there has been no problem.

Len Powell Finksburg, MD

[#10134 - October 2013]

Can Resistors Make the Difference?

I'm working on an audiophile-quality all-transistor amp. I was told that carbon film resistors are less noisy than wire-wound precision resistors — which are more expensive. Could I hear the difference in resistors? Is there a theoretical noise difference?

Carbon composition resistors are THE WORST THINGS TO USE in an audiophile amp as their "absolute value" tolerances range from 10-20%. Plus, their "absolute resistance" values are very susceptible to heating and cooling effects (i.e., they get warm and their resistance changes — sometimes dramatically!).

Instead of using wire-wounds, use metal-film resistors. Their tolerances are 5% or less, they're very stable overall, and aren't as susceptible to temperature effects like carbons. Plus, they're much cheaper than wire-wounds.

Ken Simmons Auburn, WA

[#10135 - October 2013]

Audio Amp ICs

I need a good, single-source audio amp IC for a project. The LM-386 isn't powerful enough. Is there a 'super' LM-386 op-amp that's also single-source (only one power connection)?

Depending on your power and voltage requirements, I would suggest the LM380 or LM384. I have used

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