On 2011-12-29 17:01 +0000, Justin Owen wrote: > 4) dB = 20 log10 (Vout / Vin) Looks like you want a gain, so this one. Careful when measuring small AC voltages. Some otherwise good DMM can be pretty poor at that. Mine reads 10 mVAC with the leads shorted ! -- André Majorel http://www.teaser.fr/~amajorel/