hi
im building an auduino project, im trying to switch 2 * +5v into two pins not having much luck in my circuit, this is the circuit im using seems to do the opposite when the switch is made ive got a 0v to pin could someone please check my circuit thanks

 

Maybe I'm just tired, but I don't know what you are trying to do....

Your circuit will only have 5V on the output when the input to the 2N7000 is below the threshold voltage(logic 0) as the transistor will not be conducting. The 1kΩ resistor pulls the voltage up to +5V.

When the input to the MOSFET is above the threshold voltage, the transistor will conduct, pulling the output to 0V.

Why not simply use the switch? Why is the MOSFET there at all?

 

Why would you expect it to be otherwise? When you apply 5V to the gate the transistors turns on and pulls the pin low.

 

i thought it would be interesting to try another way to switch a +5v instead of a button
ok i understand now, why im getting a gnd when +5 is present at the gate

how else could i get a +v to my pin instead of using a push button / switch?

thanks

 

how else could i get a +v to my pin instead of using a push button / switch?
thanks

A wire.







Any other method is really just using a variation of what you would be doing with a switch. A transistor, a relay, a transmission gate, etc. will all require you to switch an input, which will probably be... a switch...

 

The single Mosfet is an inverter. Add another transistor or Mosfet to make it invert twice then when the input from the auduino is high then the output is also high (but with fairly low current provided by the 1k output resistor) and when the input is low then the output will also be low.

 

You are not using a Vgs TTL level MOSFET, so the output may not as your expected.
You may try to use a transistor to be your switch:
http://www.electronics-tutorials.ws/transistor/tran_4.html

Or you can search on google :
1. Using a transistor as a switch.
2. Using a MOSFET as a switch.

You can learn more about how to using a transistor or MOSFET to be a switch.

 

You are not using a Vgs TTL level MOSFET, so the output may not as your expected.
You may try to use a transistor to be your switch:
http://www.electronics-tutorials.ws/transistor/tran_4.html

Or you can search on google :
1. Using a transistor as a switch.
2. Using a MOSFET as a switch.

You can learn more about how to using a transistor or MOSFET to be a switch.

A MOSFET is a transistor, I think you mean BJT....

 

A MOSFET is a transistor, I think you mean BJT....

Yes.
Although the BJT and MOSFET are all belongs to Transistor, but BJT is the abbreviation of Bipolar Junction Transistor, normally when we say transistor that is talking about BJT, and say MOSFET is talking about MOSFET.

If you type 'transistor' to search on google then you will know what I mean.

 

And MOSFET stands for Metal–Oxide–Semiconductor Field-Effect Transistor..
What google has to say about this is irrelevant, this is a site dedicated to electronics in detail, so when you make a distinction about types of transistor I think you should say "bjt or mosfet", not "transistor or mosfet".

 

With a 5V supply and a 1k output resistor then the max output current is only 5mA. the 2N7000 Mosfet is spec'd to conduct very well when its gate-source voltage is only 4.5V so it will work fine.

But why is the output resistor chosen with such a high value (1k) that the max output current is nearly nothing? The arduino can supply much more current WITHOUT the Mosfets.

 

And MOSFET stands for Metal–Oxide–Semiconductor Field-Effect Transistor..
What google has to say about this is irrelevant, this is a site dedicated to electronics in detail, so when you make a distinction about types of transistor I think you should say "bjt or mosfet", not "transistor or mosfet".

The first transistor is the BJT, so the transistor is represent the BJT as the Ancestor of transistors, use BJT that just emphasize the transistor which talking to is a BJT, sometimes I also do that.

Although there are many kinds of transistors developed, but when I say transistor that is point to a BJT, when I say some other transistors then I will type the name of that kind of transistor as MOSFET or JFET or UJT.
Although we discussing on this site, but If you want to get some more infos then you can't just search on this site, that is not enough, so when you search the EE infos on google, if you use bjt to search will get less info than transistor.

Here is some search compared form google.
using bjt as switch - About 405,000 results (0.35 seconds)
using transistor as switch - About 14,300,000 results (0.17 seconds)
bjt - About 10,900,000 results (0.17 seconds)
transistor - About 63,800,000 results (0.20 seconds)

Don't tell me that you don't want to search on google.

So when I say transistor and MOSFET, I don't think there is nothing wrong, it's very clear that is pointed two different parts, I think there are many people will doing the same thing as I did.

 

The first transistor is the BJT, so the transistor is represent the BJT as the Ancestor of transistors, use BJT that just emphasize the transistor which talking to is a BJT, sometimes I also do that.

Although there are many kinds of transistors developed, but when I say transistor that is point to a BJT, when I say some other transistors then I will type the name of that kind of transistor as MOSFET or JFET or UJT.
Although we discussing on this site, but If you want to get some more infos then you can't just search on this site, that is not enough, so when you search the EE infos on google, if you use bjt to search will get less info than transistor.

Here is some search compared form google.
using bjt as switch - About 405,000 results (0.35 seconds)
using transistor as switch - About 14,300,000 results (0.17 seconds)
bjt - About 10,900,000 results (0.17 seconds)
transistor - About 63,800,000 results (0.20 seconds)

Don't tell me that you don't want to search on google.

So when I say transistor and MOSFET, I don't think there is nothing wrong, it's very clear that is pointed two different parts, I think there are many people will doing the same thing as I did.

Actually, FETs were the first transistors. They were patented and described in depth well before a BJT was ever created. The BJT was the first one created, but was only by accident while waiting for the technology to create a FET.

It doesn't matter what misrepresented data there is on the internet a transistor is not a BJT. A BJT is a transistor.

This would be like saying I you need to pick between a fruit and an orange.

So when I say transistor and MOSFET, I don't think there is nothing wrong

I'm glad we can all agree!

 

Actually, FETs were the first transistors. They were patented and described in depth well before a BJT was ever created. The BJT was the first one created, but was only by accident while waiting for the technology to create a FET.

Thanks.
I thnk many people will treat the BJT as the first transistor like me.
This is the missing part of the transistor developing history to me.
Can you get some more infos about this?

 

Thanks.
This is the missing part of the transistor developing history to me.
Can you get some more infos about this?

The patent

An improvement on it

http://www.todaysengineer.org/2003/May/history.asp

A book to read

 

The patent

An improvement on it

http://www.todaysengineer.org/2003/May/history.asp

A book to read

Thanks.
The linked pages of the first and second lines that it looks like using the french.
So I will see the three and four.

 

What? All four are in english. Maybe try setting the language in the top right corner on the first two links?

 

What? All four are in english. Maybe try setting the language in the top right corner on the first two links?

Thanks.
I recheck the links, the first link is english info.
The second link on the page is english, but the data looks like french.

This page has two files,FR786454 (A), BE408194 (A)
http://worldwide.espacenet.com/publ...&DB=&locale=en_EP&CC=GB&NR=439457A&KC=A&ND=1#

 

Those are french and belgian applies for the same patent, see the "Also published as:" line right next to it?
Click on "original document" in the menu on the left.
If you cant navigate a web page, do you think you will understand the language of patents? I rarely have the guts to read them all the way through.

 

Those are french and belgian applies for the same patent, see the "Also published as:" line right next to it?
Click on "original document" in the menu on the left.
If you cant navigate a web page, do you think you will understand the language of patents? I rarely have the guts to read them all the way through.

Thanks.
I get into the web pages as you mentioned, and choosing the Original document to see, there are so many english documents , the last times that I get into the same page, but I didn't choose the original documents.

I want to know about what tshuck mentioned that FET is the first transtistor, I would like to know the history like a story.