Where would a transistor be put??

[Neutrideo]

Please check the pic below and maybe tell me where a transistor would go, Thanks all, By

[vanished]

-moved to electronics-

[Himommies]

Wtf is even going on here

labels?

[vanished]

I googled this image and it appears it's a design for how to output text to that LCD display.  I also noticed that in none of the instructions did anyone mention a transistor anywhere, so I don't know where you've got the idea you need to add one.

[sazrocks]

Why would that project need a transistor?

[Neutrideo]

I was trying the project and my it teacher suggested a transistor, but he didn't know where. Because the screen wouldn't power on.

[MadModder]

It needs a transistor for the LCD to be backlit. You want to connect the "Base" to the Arduino PWM (#3), the "Collector" to the Arduino 5V, and the "Emitter" to the Arduino GRND. Kind of a BS schematic though, since it's missing resistors, diodes, etc. that are definitely needed for this type of circuit.

I know all of the basic stuff is confusing at first, but stick with it. Soon it will become exciting, and instead of doodling, or doing crossword puzzles, you'll be drawing out circuits you never intend to build. You'll do it just for the fun of it, and to create puzzles to solve.

P.S. You might want to throw an Attenuator in the mix to control the brightness of the LCD.

 

[Neutrideo]

1 hour ago, MadModder said:

It needs a transistor for the LCD to be backlit. You want to connect the "Base" to the Arduino PWM (#3), the "Collector" to the Arduino 5V, and the "Emitter" to the Arduino GRND. Kind of a BS schematic though, since it's missing resistors, diodes, etc. that are definitely needed for this type of circuit.

I know all of the basic stuff is confusing at first, but stick with it. Soon it will become exciting, and instead of doodling, or doing crossword puzzles, you'll be drawing out circuits you never intend to build. You'll do it just for the fun of it, and to create puzzles to solve.

P.S. You might want to throw an Attenuator in the mix to control the brightness of the LCD.

 

I dont know how to read this

[MadModder]

Well, your question was where a transistor would be connected. If you're just trying to connect an LCD to a Arduino, then this article might explain things to you. However, it's using an attenuator to control the LCD lighting.

 

http://www.instructables.com/id/Connecting-an-LCD-to-the-Arduino/

 

 

[vanished]

2 hours ago, Neutrideo said:

I was trying the project and my it teacher suggested a transistor, but he didn't know where. Because the screen wouldn't power on.

lol  sounds like they have no idea what they're doing.  Seriously, try to name any situation where it makes sense to say "I think you need <blank> but I have no idea where".  If you knew it was needed, you'd know where, and vice versa.

[Neutrideo]

4 minutes ago, Ryan_Vickers said:

lol  sounds like they have no idea what they're doing.  Seriously, try to name any situation where it makes sense to say "I think you need <blank> but I have no idea where".  If you knew it was needed, you'd know where, and vice versa.

he is quite stupid, but from my research it you do need it for the lcd to be backlit as the previous person said

[vanished]

1 minute ago, Neutrideo said:

he is quite stupid, but from my research it you do need it for the lcd to be backlit as the previous person said

I'll let you try to work it out with @MadModder then since I have no idea either tbh.  As far as I can tell from the quick search I did, this should function as shown.

[MadModder]

Sheesh!  I thought he was throwing a problem at you, and making you find a solution. Not all LCD's need to be backlit, and some you don't want to be backlit. If this is not just on paper, what LCD are you trying to use? Manufacturer, and part/model # ? I've used/programmed a few different types, so if you can give me some info I can tell you how to proceed, and if you need a transistor, or not. I just assumed you were supposed to include a transistor. It could be as simple as not providing enough power for the LCD you're trying to use.

I'm off to try some new stuff just released on the PUBG beta server, but I'll check back later.

[Neutrideo]

1 hour ago, MadModder said:

Sheesh!  I thought he was throwing a problem at you, and making you find a solution. Not all LCD's need to be backlit, and some you don't want to be backlit. If this is not just on paper, what LCD are you trying to use? Manufacturer, and part/model # ? I've used/programmed a few different types, so if you can give me some info I can tell you how to proceed, and if you need a transistor, or not. I just assumed you were supposed to include a transistor. It could be as simple as not providing enough power for the LCD you're trying to use.

I'm off to try some new stuff just released on the PUBG beta server, but I'll check back later.

i will check next lesson, thx!

[You_are_a_cunt]

10 hours ago, Ryan_Vickers said:

lol  sounds like they have no idea what they're doing.  Seriously, try to name any situation where it makes sense to say "I think you need <blank> but I have no idea where".  If you knew it was needed, you'd know where, and vice versa.

I think you need RGB but I have no idea where. ('cause everything is already RGB!)

 

[mariushm]

The Arduino can output reliably up to 40mA through most pins, and up to 200mA in total.

If the voltage is lower than 5v, then the current may be a bit lower.

 

The LCD display has a backlight, but the leds may use more than 40mA or quite close to 40mA so maybe you could just connect the backlight of your LCD display to one of your Arduino pins. By sending a digital 1 on that pin, you would send power to the leds and the backlight would be lit.

 

As an alternative, you can use a transistor as a on/off switch. When a bit of current goes in the base pin of a transistor, the transistor turns on and current flows between collector and emitter.  So using less than 1mA of current (from the Arduino pin into the transistor), you can have more than 40mA going into the LED backlight.

 

You can learn a lot about transistors watching this video ... for your needs, you can just replace the solenoid valve with the  led backlight (the + and - pins of the led backlight)

 

 

A more advanced application would be to use a transistor in its "between fully off and fully on" state to control the amount of current the backlight gets.  By replacing the resistor on the base pin of the transistor with a potentiometer, you would be able to control how much current goes in the base pin, which in turn will control how much current will flow between collector and emitter, so the led backlight will vary in brightness.

 

But this is really tricky and not recommended, because that range where the transistor is between fully off and fully on... that range is quite small in the first place but can narrow or enlarge depending on how warm the transistor is, and also varies from transistor to transistor even if it's the same model of transistor.

 

edit:

 

If you have RGB backlight, it's an even better case for using transistors (or mosfets) to control each color in the backlight. If each color uses 30-50mA, then when you want a white backlight on the lcd display, you'd send 90-150 mA to the led backlight through Arduino pins, which may be a bad idea or even impossible. Instead, you could use 3 transistors and the Arduino will use only a few mA of current and you power the led backlight directly from the power supply.