Arduino Forum

Using Arduino => General Electronics => Topic started by: DucksandCo on Jun 14, 2019, 12:37 am

Title: Circuit Symbol
Post by: DucksandCo on Jun 14, 2019, 12:37 am
Hello all,

I am currently making a sprinkler system that waters its plants when the soil is dry enough. My teacher has drew in this diagram regarding how I should hook up my transistor. I dont really know what symbol this really is.

http://Resistor https://imgur.com/gallery/qd8FBSI


This is the actual arduino setup.

http://Ard
https://imgur.com/gallery/YCkygPm


Thank you.
Title: Re: Circuit Symbol
Post by: dl324 on Jun 14, 2019, 12:56 am
I am currently making a sprinkler system that waters its plants when the soil is dry enough. My teacher has drew in this diagram regarding how I should hook up my transistor. I dont really know what symbol this really is.

(https://imgur.com/gallery/qd8FBSI)

This is the actual arduino setup.

(https://imgur.com/gallery/YCkygPm)
I've found posting pictures on this forum to be somewhat cumbersome.  I see what appears to be two images, but nothing is visible.

EDIT: fiddling with images...
(https://forum.arduino.cc/index.php?action=dlattach;topic=621313.0;attach=312597)

No clue what your teacher is referring to.  We need to know the part number because there are three different pinouts for TO-92 transistors (2N, BC, and 2S).  Since one pin in grounded, I'm guessing it's an NPN transistor with the emitter grounded.
Title: Re: Circuit Symbol
Post by: Southpark on Jun 14, 2019, 02:05 am
My teacher has drew in this diagram regarding how I should hook up my transistor. I dont really know what symbol this really is.
https://imgur.com/gallery/qd8FBSI
Adequate information is required in order to make sense of a circuit diagram. In this case --- not enough information. Device details (eg. transistor model etc) is needed. Also - intended purpose --- ie. what is required for it to do --- should be understood in advance as well.

In this case, there's not enough details. More details are required.
Title: Re: Circuit Symbol
Post by: larryd on Jun 14, 2019, 02:11 am
Boy oh boy, looks like - GND to Emitter, + to maybe a solenoid then maybe the Collector, Dout from an Arduino to the Base.



Title: Re: Circuit Symbol
Post by: dl324 on Jun 14, 2019, 03:37 am
After looking at your second picture, I could see that you're using a transistor in TO-220.

This is the pinout:
(https://forum.arduino.cc/index.php?action=dlattach;topic=621313.0;attach=312612)
Your teacher should have drawn the schematic this way:
(https://forum.arduino.cc/index.php?action=dlattach;topic=621313.0;attach=312614)
Title: Re: Circuit Symbol
Post by: Southpark on Jun 14, 2019, 07:18 am
Could it be a logic level mosfet too?
Title: Re: Circuit Symbol
Post by: larryd on Jun 14, 2019, 07:23 am
Forgot to include a kickback diode.

:(







Title: Re: Circuit Symbol
Post by: Paul__B on Jun 14, 2019, 02:31 pm
Oh dear, pictures (clickable)!

(https://i.imgur.com/rpwBhlq.jpg) (https://i.imgur.com/rpwBhlq.jpg)

(https://i.imgur.com/RrM4ALr.jpg) (https://i.imgur.com/RrM4ALr.jpg)

(https://i.imgur.com/6gCjXVJ.jpg) (https://i.imgur.com/6gCjXVJ.jpg)
Title: Re: Circuit Symbol
Post by: dl324 on Jun 14, 2019, 04:51 pm
Forgot to include a kickback diode.
If your response was regarding my post, I redrew what the teacher drew, not what it should have been.
Title: Re: Circuit Symbol
Post by: dl324 on Jun 14, 2019, 05:30 pm
Could it be a logic level mosfet too?
The resistor on the lead marked Dout wouldn't be necessary and a resistor from gate to source would have been included so the gate wouldn't float when the GPIO port wasn't active.
Title: Re: Circuit Symbol
Post by: larryd on Jun 14, 2019, 05:35 pm
If your response was regarding my post, I redrew what the teacher drew, not what it should have been.
No, I was looking at the teachers image.


Title: Re: Circuit Symbol
Post by: Southpark on Jun 14, 2019, 11:43 pm
The resistor on the lead marked Dout wouldn't be necessary and a resistor from gate to source would have been included so the gate wouldn't float when the GPIO port wasn't active.
This is all based on assumptions, which is why it can be a time-wasting exercise if there's inadequate details to begin with.

Additionally, if you assume a BJT, then the input could become floating under those conditions you mentioned too maybe, right?

Also ----- using series resistor for gates of mosfets is not uncommon.

It may well be a BJT. And all I'm saying is - if there's not enough information to start with - then it's like a goose chase.
Title: Re: Circuit Symbol
Post by: Southpark on Jun 15, 2019, 11:10 am
Make sure your breadboard connections are correct too. Example..... hole j1 has an orange wire..... but the purpose of it is unclear. Same for hole c1.