Hello Everyone,
I was just thinking. If I build an Arduino UNO on a protoboard and I use two of the holes on the protoboard that are in line with say code pin 5, which is, pin 11 on the ATMEGA 328
those pinholes, in the same row, are in series, right?
If I want to light, "simultaneously", two 5mm red LED's, powered with 5v, with each at 2.2 fv, and 20ma current, on the same Arduino pin, pin 11,would I splice the two positives legs wires of the LED's into a 33 ohm resistor, which is for a series hookup as per this calculator. https://www.amplifiedparts.com/tech-articles/led-parallel-series-calculator
I hope this is clear, thanks for any useful comments.
I think OP wants to connect two 5mm LEDs with a Vf of ~2.2volt in series, with a 33ohm CL resistor. Yes, that can be done.
Note that 16-20mA is an absolute max specification for a 5mm LED. They are much happier with say 5-10mA. Try a 100 ohm resistor, which is also much safer for the Arduino pin.
Leo..
Ok, so you are saying each led should have its own resistor, right? So, 140ohm resistor for each RED led, right? Even if both are being fed by pin 11 on the atmega328
Pic shows Arduino UNO NOT "protoboard", with two red led's in series with 33 ohm resistor, they work
I am seeing the two LED’s on the left connected in parallel with a 36 ohm current limiting resistor. They are powered from pin 5 of the Uno.
In order to connect the LED’s in series you need to connect the cathode of the first LED to the anode of the second one. The cathode of the first is then connected to the resistor and the cathode of the second is connected to ground.
So starting from pin 5 of the Uno:
Pin 5 to
Resistor
Other end of resistor to
Anode of LED 1
Cathode of LED 1 to
Anode of LED 2
Cathode of LED 2 to
GND
I would have drawn the diagram but it would take me longer.
Your “33” ohm resistor is actually 36 ohms. Not that that makes any real difference. A 33 ohm will have orange-orange-black stripes, not orange-blue-black.
Ok, I just hooked it up in series and it's working. So tell me, I am confused, how do I do the same on a protoboard where you have 1 row of holes for each pin terminal using an atmega328 microcontroller?
Place discrete components in the open space "above" and "below" the atmega328p and run jumpers from the atmega328p pins to the components, or place discrete component legs in the atmega328p leg rows, then directly to Vcc or GND.
