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Electronics => Projects, Designs, and Technical Stuff => Topic started by: DestinySpork on May 16, 2015, 09:01:51 pm

Title: 3 state me memory cell
Post by: DestinySpork on May 16, 2015, 09:01:51 pm
Could someone help with circuit design? What I need is a circuit that will toggle the state of 3 leds with 3 pushbutton switches. If it can be designed with cheap and common components it would be even better :) I know i t seems like a pretty simple thing, but help would be greatly appreciated.

The attached is what I have for switching 2 outputs, which will hopefully show what functionality I'm looking for as well as componentry
Title: Re: 3 state me memory cell
Post by: Zero999 on May 16, 2015, 09:46:52 pm
Is this the sort of thing you're after?
(https://www.eevblog.com/forum/projects/discrete-logic-design-vs-a-super-cheap-micro/?action=dlattach;attach=140783;image)
https://www.eevblog.com/forum/projects/discrete-logic-design-vs-a-super-cheap-micro/msg624939/#msg624939 (https://www.eevblog.com/forum/projects/discrete-logic-design-vs-a-super-cheap-micro/msg624939/#msg624939)

Obviously you need to add some series resistors and LEDs.
Title: Re: 3 state me memory cell
Post by: Rerouter on May 16, 2015, 10:13:14 pm
or if you want it in descrete components, here you go,

each cell has

1x NPN transistor
1x PNP transistor
3 1K resistors
1 switch to ground
1 diode
n-1 diodes, where n is the number of memory cells,
1 led,

This design is fairly immune to transistor gain variances,
Title: Re: 3 state me memory cell
Post by: Someone on May 16, 2015, 11:25:03 pm
Could someone help with circuit design? What I need is a circuit that will toggle the state of 3 leds with 3 pushbutton switches. If it can be designed with cheap and common components it would be even better :)
https://www.eevblog.com/forum/projects/discrete-logic-design-vs-a-super-cheap-micro/msg624939/#msg624939 (https://www.eevblog.com/forum/projects/discrete-logic-design-vs-a-super-cheap-micro/msg624939/#msg624939)
The 3 way solution I showed in that thread uses the same design pattern as the original here, adding ORing diodes to extend it. You could even use some of the ORing diodes as the indicators here saving a few more components.
Title: Re: 3 state me memory cell
Post by: DestinySpork on May 17, 2015, 12:44:07 pm
Thanks everyone for your contribution :) I will use rerouters design as it uses nice discreet components which I already have :)  :-+