Question about transistors

Hi . I decided to make an awesome transistor driver for direct drive dc motors without PNP transistors . Simple but effective . On top of that , I wanted to use it with arduino and the digitalWrite() ; function (doesn't support PWM) but the problem is that I my design is a bit 'weird' and works with the technology of changing polarity (lets say you want your motor to spin . You use digitalwrite and power a bunch of transistor bases and as a result , external power supply's + goes to motor pin A and - to B . Then you want reverse , you digitalWrite ANOTHER pin and - goes to A and + to be .
Now the problem :
Don't know if the base and collectors current get 'mixed up' or not : Arduino digitalWrites output is positive while I want GND to pass from collector => emitter ; is that possible ?
Basically , can I give positive to base while collector receives negative and emitter emits negative ?
Thanks in advance .

If you are asking for advice on what you believe to be a novel circuit, you will need to post a schematic. Your verbose description does nothing to make someone unfamiliar understand how you intend to wire it.

Hi . I decided to make an awesome transistor driver for direct drive dc motors without PNP transistors.

So you mean you want to use only NPN transistors?

Then you want reverse...

Without taking the time to draw-up a schematic and analyze it myself I'm not 100% sure about this..... I think it can be done but I think you'll need a positive & negative power supply if you are only using NPN transistors.

Don't know if the base and collectors current get 'mixed up' or not...

If you look at the schematic of a transistor, current flows from positive to negative in the direction of the "arrow". The current is controlled by the base-emitter voltage, with the base current also flowing from positive to negative in the direction of the arrow. (The emitter current is the sum of emitter-collector current and the base-current.)

Simple but effective

That's a bold claim for something that hasn't been shown to work yet! :smiley:

Actually, the simplest way to reverse a motor is with a DPDT relay. You'll need another transistor or relay to turn the motor on & off.

Ok . I’ve attached a fritzing schematic (.fzz) file below . Here’s an image if you don’t like to download the (.fzz) file :

(Image made using the fritzing application)
Basic idea :

So my question is that , can I pass GND from collector => emitter whilst the base is powered with +5v ?
thanks in advance !

Motor Driver.fzz (7.64 KB)

Simple but effective

That's a bold claim for something that hasn't been shown to work yet! :smiley:

Simple but effective idea XD

With all respect to those who love Fritzing, it’s not a schematic. That’s a jumble of wires.

THESE are schematics…

robn2 tutorial v1.4.bmp (403 KB)

38k generator receiver.bmp (102 KB)

sounds like an h-bridge..

no that's not a scehamtic! that's a picture with lines on it :slight_smile:

Hi again . I made something you might call schematic . I used colored wires so it wouldn’t be confusing (I hope THAT’S not related to being a schematic or not ? :smiley: )
Files are attached . Didn’t put a picture because it’d be a big one and the page would get ‘ugly’ and confusing (and hard to navigate in)

This can or cannot be an H-Bridge . Usually , any circuit that drives motors in both directions is called an H-bridge . So Yes, this is an H-bridge . But some say any circuit that drives is an H-bridge . Then again it is . But some believe it should have both PNPs and NPNs , if so , this won’t be one .

Besides , my question isn’t involved in the circuit in any way , I’m just asking can I give +5v to BASE and GND to COLLECTOR ? (And not burn the arduino)
Thanks in advance !
(I bet I should use PNPs for GND connection and NPNs for Voltage connection)

Technical schematic.fzz (4.14 KB)

Nothing is attached.

Thanks XD forgot . Fixed .

can I give +5v to BASE and GND to COLLECTOR ? (And not burn the arduino)

As a circuit designer, you should already know the answer to that question. But, no.

Some of us don't have Fritzing and don't want it. Could you post a screenshot?

Hi , ok thanks . problem solved . So I guess I should use PNPs for the GND connection , right ?

No, you normally use PNP for connection to the positive connection, but please draw a schematic.

Pelle

Here's the 'wrong' schematic .

So how do I switch GND (= control the GND current with a transistor ?)

That does not work.
Q3 and Q4 have Collector and Emitter reversed
The motor don’t get current at all or you make an short.

This is an design witch work with all power voltage.

H-Bridge-5.gif

So far the only schematics I can see are those you've labeled 'wrong' schematic .
I can also see some "jetScreenshot" logos (presumably because you have not made those images available to the public.)

In the wrong schematic, you show the emitters and collectors quite clearly YET you treat them as though they're interchangeable. The reason that all three connections on a transistor have different names (and symbols) is that each leg has it's purpose.

I'd suggest you do some reading on the use of transistors and how they work.

'Jetscreenshot' is the app used to take screenshots and upload them .
'wrong schematics' - they say it's wrong , I don't know .
'transistors' - I'm using them to allow or not allow current , and I'm stuck how to allow/not allow the GND connection . My question from the beginning . I know the basics , why we use them and how . And no , I don't know WHO made them , HOW are they made , WHAT other purposes they have or etc etc etc .
No , the connection of transistors are somehow what I want them to be : 2x A transistors' base tied together to digital pin X and 2x B transistors tied together to digital pin Y . Arduino digital output turns 2x A transistors on => GND goes to motor's first pin and + to it's second . Arduino digital output turns 2x B transistors on => + goes to motor's first pin and GND to its second - result :
motor can spin in 2 different directions
advantage : works with digitalWrite code

Jetscreenshots are not compatible with Mac, what i can se
Your schematic in reply 14 doesn't do anything except an short.
"I don't think the basics how to use transistors", use a book or google.
"HOW they are made", use a book or wikipedia.
"WHO made them", not important all with the same number and letters are almost equivalent.
It's not possible to connect 2 base to the arduino output an get it work as a H-bridge.

If you use my schematic (from Google pictures) you get it work. Spining the motor in both directions but drive only A or B at a time.
Use yor new knowledge about transistor an analyze the scheamatic.

Pelle

Pelleplutt:
Jetscreenshots are not compatible with Mac, what i can se
Your schematic in reply 14 doesn't do anything except an short.
"I don't think the basics how to use transistors", use a book or google.
"HOW they are made", use a book or wikipedia.
"WHO made them", not important all with the same number and letters are almost equivalent.
It's not possible to connect 2 base to the arduino output an get it work as a H-bridge.

If you use my schematic (from Google pictures) you get it work. Spining the motor in both directions but drive only A or B at a time.
Use yor new knowledge about transistor an analyze the scheamatic.

Pelle

1- So you're saying the photo doesn't show up ? That's not even im-probable , its totally impossible , its a standard format photo which has been just uploaded with this tool .
2- I never said "I don't think the basics how to use transistors" - I said I do know the basics , why they are used , types of transistors , how to use them , etc etc . My question has also been answered (thanks to those who answered) already .
3-

"HOW they are made", use a book or wikipedia.
"WHO made them", not important all with the same number and letters are almost equivalent.

Don't even WANT to know WHO made them nor HOW they're made .
4- "It's not possible to connect 2 base to the arduino output an get it work as a H-bridge."
As a matter of fact , it is . I'm just splitting the voltage between 2x transistors , which would turn them ON .
Thanks everyone .