simple control a dc motor via arduino uno ?

[majico]

hi sirs, this is my first topic in this forums ..
i want to control a 12v and a 5v dc motor with 2 terminals only .. not steppers .. and i have not a drive motor shield or its IC. i want not to control their speeds but enable and disable them by my arduino and i fear of high current that can reverse on arduino borad even from a simple 1.5 volt motor so i prefers safety first ..
all i have - my arduino uno & these 2 dc motors and 2 tansistors S15D40 & bld135d
that in my hand at time so can i use them instead of mosfet trans. ? and keep the arduino safe .. knowing that
my pwer source is 12/5 v with 2A
AND SORRY FOR MY BAD ENGLISH

 

[Harald Kapp]

Welcome to electronicspoint.

You'll find the answers in our ressource section.

 

[majico]

Welcome to electronicspoint.

You'll find the answers in our ressource section.

thank you very very much sir <3 you really helped me so much .(y)

 

[majico]

but i wonder why this diode must connected parallel not series with the motor or the inductive ?

 

[Minder]

BEMF diode in the event that sudden disconnection of power.
Normally a DC motor that is controlled, generates a DC voltage in the same polarity as the supply, and opposes it.
If turned off suddenly a BEMF in the opposite polarity can occur which is suppressed by the diode.
This is a good link.
http://forum.allaboutcircuits.com/threads/how-to-measure-the-back-emf-of-a-dc-motor.109750/
M.

 

[Alec_t]

Without that diode the transistor will die.

 

[majico]

Without that diode the transistor will die.

i know bro .. it prevent current to return back ( make the connection reverse baise ) but why it parallel not series

 

[majico]

BEMF diode in the event that sudden disconnection of power.
Normally a DC motor that is controlled, generates a DC voltage in the same polarity as the supply, and opposes it.
If turned off suddenly a BEMF in the opposite polarity can occur which is suppressed by the diode.
This is a good link.
http://forum.allaboutcircuits.com/threads/how-to-measure-the-back-emf-of-a-dc-motor.109750/
M.

thank you very much .. that was accurate

 

[Alec_t]

but why it parallel not series

So that the high back-emf voltage is clamped to the supply voltage and to provide a re-circulating current path to enable energy stored in the inductor to be dissipated.