> > Neurons don't say much to each other unless there is an error signal.
I am not even sure what would count as an "error signal" in the case of neurons. A neuron, in the generic case, fires when its membrane potential reaches a certain threshold value. /NJ/ On Tue, Aug 28, 2012 at 7:34 PM, Alan Grimes <[email protected]> wrote: > om > > The elemental unit of an analog computer, akin to an NAND gate, is the > operational amplifier. The canonical opamp is the LM741, which was > introduced in 1968 and is still the standard opamp that everyone uses. > The Japanese have an equivalent part which has pretty much identical specs. > > Better parts are now available but engineers usually start out with the > LM741 and chose a different part only if it can't meet their performance > goals. I'm kinda fond of the Jfet input opamps myself but they can be a > bit more fragile. > > I did some computer simulations of my father's stereo (made in 1974). > The power amplifiers are basically power opamps made with discreet parts. > > You think of an amplifier as conveying a signal from input to output. A > classic tube amplifier does exactly that, sometimes with 6-12 db of > negative feedback.The creepy thing about the simulation was that the > signal appeared to disappear in the middle of the circuit, so I had > trouble even figuring out which wire was even conveying it. > > Logically, the signal MUST pass from the collector of Q402 to the base > of Q410. However the voltage swing at that point is many decimal places > below the DC voltage at that point. > > But that's the thing. The amplifier doesn't amplify signal! The > difference between the voltages at the input parts, (Q402, non > inverting, Q404 inverting). is in the microvolts range. (Q406 is > basically a 2mA CCS with a 20-30 second time delay), so the input signal > to the amplifier is essentially null. > > But the circuit does work. It has a gain defined by R410 and R414. > > It is an error amplifier. The brain works in much the same way. Neurons > don't say much to each other unless there is an error signal. The > amplifier's output is your imagination and the input signal are your > sense organs. > > Anyway, just a different perspective. =P > > -- > E T F > N H E > D E D > > Powers are not rights. > > > > > ------------------------------------------- > AGI > Archives: https://www.listbox.com/member/archive/303/=now > RSS Feed: https://www.listbox.com/member/archive/rss/303/20912103-eed2d0e1 > Modify Your Subscription: > https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com > ------------------------------------------- AGI Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/21088071-c97d2393 Modify Your Subscription: https://www.listbox.com/member/?member_id=21088071&id_secret=21088071-2484a968 Powered by Listbox: http://www.listbox.com
