GCSE Electronics

[frenulem - No.5417]

It's time for my coursework again, and i want to make a lamp........yes a lamp -_-

The details of what i wish to achieve is a RGB PIC programed multi colour lamp, so 1 green 1 red 1 blue, or 2 green, 2 red, 2 blue. then the PIC will then change the colors.

So to produce yellow the red and green LEDs will be lit, and then put through frosted plastic to give a nice affect.

For the input i want to use QTC (Quantum tunnelling composite) so the more pressure it will change colour

What i want to know is:
Is this possible?
What IC should i use?
What calculations i would need to do

Initial Design:

[FOOKz™]

Basically QTC is a material the exploits a phenomenon in quantum-electrical properties that electrons will always conduct in materials even when resistance is extreme.


just play around with the material. You'll need something like a diode ladder to drop a specific amount of voltage at a consistent rate.



hook each output of the diode to a pic I/O pin and program it to say if:

pin2 is high; pin3 is low; pin is low; you want green
pin2 is high; pin3 is high; pin is low; you want yellow
pin2 is high; pin3 is high; pin is high; you want red

edit: forgot to mention that diodes are like resistors that turn on when 0.6v to 0.7v is applied to the cathode.

diodes will always drop approximately 0.6 or 0.7 just like a resistor.

[frenulem - No.5417]

Allways DROP 0.6 to 0.7?

[FOOKz™]

Allways DROP 0.6 to 0.7?

Well you can argue that there are diode like zener, clamper, rectifier diodes that drop different voltages....

a 1N4001 diode normally drops 0.6 and 0.7 volts. *sometimes 0.8 if hot

Zener diodes are Tuned to drop a certain amount to regulate voltage... like 5.5v or 9.4v or even 0.2v

[frenulem - No.5417]

sorry i read it wrong, i thought you said it would drop 0.6v Down to 0.7v and i was like, surely thats going up. But i see what you mean now just trying to find the right PIC AXE IC Hyper said i needed 3 PWM and 1 ADC pin i think the PIC14M2 looks like it, right?

[hyper999]

well i wouldnt go 100% on my word as i'm not really very qualified but i'm assuming you would want a pwm chanel for each color led and an adc channel to get a reading from your QTC.

as for the pic14m2 i have no idea what that is as that is just the name gien to the pic after the PIC AXE company has loaded their bootloader on it not the name given by microchip

EDIT: also i cant find it on the picaxe website either?

[frenulem - No.5417]

http://www.rev-ed.co.uk/docs/picaxe_manual1.pdf PG 28

[hyper999]

looks ok to me

[Jeff Bobbo]

Surely when you remove the pressure from the QTC, there would be no increased resistance... So it would turn off instantly? You'd need some way of stopping that, could be purely software based within the PIC though.