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slowing time constant(discharge) for cap

so....I'm back again!...

I have a small question,

I have finished a perfect classical conditioning analogue circuit for an AI, now i am gonna be using 4 "lobes" for the brain, i.e, touch sensor, colour sensor, memory bank, and output load. I am gonna be using the 2 different sensors for the stimulus(reward and neutral) and the output load for the response...of course,

so, I am gonna be using some arrays of capacitors as the memory bank, but a capacitor dishcarges fast...1.how do i slow the discharge?

I have a solution that I don't know if it will work, here's an example circuit that I crudely drew :P ....btw, this is not the memory bank of course, just an example to slow down the discharge...2. will this work?:

btw, to operate the circuit above, first charge the caps using the charging switch, then turn it off, then turn the main swith of the transistor......(note: transistor is used as a switch here)will the time constant slow down because of the resistor and the sum of the parallel capacitor? and will the amount of the resistance and the capacitance will be directly proportional as the time? (i saw  a subject saying that t=r.c....(t=time constant in sec.)


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Try playing around with this calculator.

Yes, in general a larger resistor will stretch out the RC constant on a given capacitor value, and capacitors in parallel like you have them sketched will act as a single one with their values added.  Keep in mind that usually the Constant is the time it takes for the capacitor to go through 63.3% of its charge (whether charging or discharging.)  

Whether that means the circuit you've drawn will do what you're thinking it will, I'm still unclear on and probably depends largely on the values and types of components you can round up.  As always, keep us updated though.  Your explorations are always fascinating and artful!

I will try that calculator, I realy hope this capacitor will really slow down it's discharge.

but of course, that's why there is experimentation! I will experiment and see the results

Hi, MetalmonkeeLad. I started to answer this, but there is something I am not sure about. Since you mentioned both a memory device and slowing down a motor, I am thinking of these as different things. As a memory bit, I am thinking you would want to have the transistor full on, as long as the cap is charged, and at a certain point of discharge, have it switch off, with no inbetween values.

For the motor speed control, I am thinking you mean you want to use the charge level to let the motor slow down as the charge drops.

These would be done slightly differently. Could you elaborate a wee bit more?

In leiu of further explanation, if you need a memory device that will hold the same level until switched, I would point you to a flip-flop circuit which needs 2 transistors (or more).

The circuit you have will essentially work for motor speed control, but I might suggest an FET instead of a bipolar transistor, since FETs switch according to voltage at the input (gate) and the resistor (tied between gate and ground) will still drain the charge from the cap(s) but may be a much higher value for a longer time before the cap is completely discharged.

no, I am not thinking of motor speed control....or slowing down the motor, I am thinking of slowing down the discharge of the capacitor since capacitors discharge fast.

the picture above is not the memory array....that's just to demonstrate if that schematic is  good thing to slow down the discharge...

I don't want to use a flip-flop since i am using my own circuit .....

and I am gonna be using a regular bipolar transistor because I am aiming for simplicity and will only use the things I can find inside our house :P

Oops, I posted my answer the wrong place.  See above...