Sunday 22 May 2016

flash - How to make 1 bit permanent memory circuit?



I would like to make a simple circuit to store or save 1 bit of data. The circuit should be able to remember the state of an LED ( on or off ) even if the supply is disconnected from the circuit. I need it to work like a hard drive, flash memory or SD memory card of cell phones.


I made a circuit as shown in the picture, The output is an LED in series with 470 ohm resistor. I use two bush buttons to charge or discharge the capacitor so the output LED is on or off.


After disconnecting the supply or turning off electricity, The circuit was able to remember the state of the LED for few minutes.


After 2 or 3 minutes, the capacitor discharged completely and the circuit lost its data.


enter image description here How can I stop the capacitor from discharging ? or how can I slow the rate of discharging so that the circuit lose its data after a week or more ?


In this circuit I uses 555 as an inverter ( not gate ) but I may use any other IC's , My aim is just making a simple permanent memory.



Answer



The original electronic nonvolatile memory is based on ferrite cores. While it's relatively easy to magnetize such a core in one direction or the other to store a one or a zero, it takes some fairly sophisticated circuitry to read it back reliably.


Modern nonvolatile chips rely on charge storage, but in order to make this work, you need to be able to create a capacitor that has essentially zero leakage, and a way to read out that charge. This can only be done in the context of microelectronics, where the capacitor is a tiny piece of metal (the "floating gate") that's completely encased in glass (silicon dioxide), and is read out by means of its influence on a nearby transistor.


Another choice is ferrorelectric RAM (FRAM), which uses a special dielectric material that has two distinct, stable polarization states. Again, this only works in microelectronics.



Therefore, you need to pick some other physical phenomenon to store your bit of information. One obvious choice is the latching relay, which stores information in the physical position of its armature, which is held in either of two stable positions by a permanent magnet or a spring. The position can be changed by applying a relatively short pulse of current, and the readout is accomplished by attaching electrical contacts to the armature.


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