Attention to people who know digital circuitry

I'm making a flashlight in my digital electronics class, and the circuit design we are supposed to use is pretty basic, so I took it up a notch and tried using logic gates to get a switch to control brightness.

This is all in theory of course.



Will this work? Essentially, if both switches are on, the AND gate should redirect the power through the resistor and (hopefully) slow the current and make the LEDs dimmer. However, if only the power switch is on, the XOR gate will direct power around the resistor, however, I assume that if the brightness switch is on and the power switch is off, the XOR gate will behave exactly the same.

I think the battery positioning is ****ed up.

This post has been edited by Ziso on Oct 8 2009, 07:24 PM

thats going to explode
i guarantee it

The 9 volt battery and the 3 LEDs work fine by themselves with one switch.

Is that porn?

now that you mention it
it looks like a guy with a gun to his head

Yeah, ban me.

fixed

so uh is your ground also the battery's negative terminal or what

EDIT: speaking of which, which end IS your negative terminal

This post has been edited by Xgoff on Oct 8 2009, 07:36 PM

That's my problem lol.

I might need two power sources for this.

This post has been edited by Ziso on Oct 8 2009, 07:39 PM

Solution?

uh

what if you connect the dimness switch directly to the power switch so that the dim switch is always off if the power switch is

EDIT: f' that would go the other way too dam

This post has been edited by Baroque on Oct 8 2009, 07:46 PM

double the power transmitted through the power switch

branch it in half and on one half put the dimness switch

connect both halves to the lights

Does boolean algebra essentially help you calculate how to do stuff like this, because I haven't learned that yet.

@Baroque, I don't know if I can do that, because 18 volts into those 3 LEDs might blow them. They are almost blinding with 9 volts in them.

This post has been edited by Ziso on Oct 8 2009, 07:49 PM

You can control brightness without logic gates, just put a switch in parallel with a resistor. But you should put a second resistor, also, to make sure it doesn't overload.

If you want to try a circuit that uses logic gates, you might want to try something else, I have a circuit diagram for a simple pause-system answering machine with only a few components (however it requires a external tape recorder).

well fine then don't double the power but you should still be branching the power switch and putting the dimness switch on one so that you cut half the power to the lights when you toggle it off

boolean algebra helps you simplify logic circuits

it won't really help you here (a flashlight really isn't something you'd use logic gates in anyway unless you were doing things like making it... flash)

I've still got to tackle one problem. The LEDs will turn on even if the main power is off, as long as the dim switch is on, thus my need for logic gates.

which is why i said, twice and now three times

make it so that there's only one power line from the power switch


then branch it in half and on one half put the dim switch

then when the dim switch is on, the first circuit from the power is broken but the second isn't

or w/e

Ok I understand you now.

I have trouble visualizing things like that.

EDIT:



There we go.

Condensed version with both switches actually within reach of the user.



This post has been edited by Ziso on Oct 8 2009, 08:13 PM