If it were possible to give objective values to the parameters in your equation it might make sense and be useful. But since many of the parameters are, if not subjective, certainly dependant on circumstance your conclusion that e(opto) > e (relay) cannot always be true. For example: if physical_volume is of little or no account e(relay) tends to infinity as it does if the price is zero (when you have surplus stock) effectiveness(x) =3D simplicity(x) * ruggedness(x) / ( physical _volume(x) > * price(x) * power_consumption(x) ) > > effectiveness(opto) > n * effectiveness(relay); n > 1 > > > > Em 27/03/2016 09:40, David C Brown escreveu: > > I prefer simple solutions and the simplest solution is a relay > > > > I like "clever" solutions, > >> Isaac > >> > >> -- > > __________________________________________ > > David C Brown > > 43 Bings Road > > Whaley Bridge > > High Peak Phone: 01663 733236 > > Derbyshire eMail: dcb.home@gmail.com > > SK23 7ND web: www.bings-knowle.co.uk/dcb > > > > > > > > > > *Sent from my etch-a-sketch* > > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb *Sent from my etch-a-sketch* --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .