Hey, this is my first time jiggling around with electric components and i basically have zero idea.. I want to use a potentiometer to dim 6 x 12V leds.. i consulted an electrician and he gave me a slight overview of the circuit: use an Arduino board, 12V dc power supply, tip31 bipolar npn transistor, potentiometer (not sure which one) and the LEDs
am not sure of how to connect the circuit and what codes to input into the arduino..
NEED HELP! many thanks
Hi, to advise, we need to know more about these leds. Can you post a link to some data about them, eg. current requirements?
Tip31would work, but there are better options these days, like logic-level FETs. These will waste less power and stay cool.
Do you want to fade each led separately?
For the pot, just a 10K linear would be fine.
Paul
Now here's a point:
Why do you want to use a potentiometer? They are becoming obsolete; wall dimmers use "up" and "down" buttons and other functions to allow automatic smooth fading, remote control, timer programming and such.
Thanks for the replies, here's the link to the details of the LEDs I want to use:
I want to fade all LEDs together
OKs so that's 120mA per led, 720mA in total. No problem at all.
Hardly seems a worthy use of an Arduino, you could do it with a 555 timer chip. Unless its the learning experience you are after. In which case you could prototype it on the Arduino and then load the sketch into an ATtiny45/85 for the final version.
OK, but how does the 555 timer work? do you connect the mains to the chip board and LEDs on the other side? and how can I use a potentiometer to adjust the brightness? for the project am working on, I need like a switch that can adjust the brightness and has a knob on it as the knob is going to be attached to a rig provided by university..
Decades before Arduino, the amateur electronics enthusiast's chip of choice for many projects was the 555 timer. It wasn't a microcontroller, but you could use it for making sounds, flashing lights, timing all sorts of things, including pwm.
Paul
I checked for the 555 timer: http://www.maplin.co.uk/p/555-monostable-switch-kit-n32fl
You reckon this can work to power 6 12v leds? And it has a potentiometer built on the chip..can that be used to alter the brightness of the LEDs?
Hmmmm.
I am very suspicious of a component labelled "107D" which bears an uncanny resemblance to a capacitor. (The black thing is clearly a bridge rectifier.) Just what "dimmable" means in this context is unclear, but I strongly suspect they do not mean by PWM.
Alright.. Which one would you recommend that i can use?
Build that first circuit on the link I gave you. You won't need diode D3 as you load is not reactive like a motor is. See the note lower down about using germanium diodes to get 1% to 99% dimming.