Hello guys,
I am new to electronics i have been playing around with them for some time.
I have recently started up a new project, i want to build a cnc router.
I have build a h bridge on a bread board and that seemed to work. But now i have build one onto proto board and i am having some trouble.
I am using tip-122 (npn) and tip-127 (pnp),
here is the schematic that i based my design on.
http://www.pocketmagic.net/wp-content/uploads/2009/03/hbridge-radu1.jpg
For a stepper motor i needed two of these h-bridges for each motor as each h-bridge controls a coil. (im using bi-polar steppers). the control signals (input) comes from an arduino.
The problem that i am having with my 1st attempt is that when i put in my power source (for the h bridge) even 5v now to test, the transistors are getting warm.. and i cant find out why?? (even with no motors or inputs connected).
I left out the diodes from the schematic as i thought they are for dc motors which might spin and cause feed back power, but that shouldnt happen with steppers? are these necessary?
Only thing that i can think of is that both the halves of the h bridge are "enabled" and power is shorting directly from the pnp to the npn. ( even with no motor connected)
Could this maybe be from the smaller transistors picking up voltage and enabling the 4 tip-122 and tip-127 transistors??
Please if any one could give me some assistance, I dono if the info i have given is sufficient, but it will be greatly appreciated!
Thanks
I am new to electronics i have been playing around with them for some time.
I have recently started up a new project, i want to build a cnc router.
I have build a h bridge on a bread board and that seemed to work. But now i have build one onto proto board and i am having some trouble.
I am using tip-122 (npn) and tip-127 (pnp),
here is the schematic that i based my design on.
http://www.pocketmagic.net/wp-content/uploads/2009/03/hbridge-radu1.jpg
For a stepper motor i needed two of these h-bridges for each motor as each h-bridge controls a coil. (im using bi-polar steppers). the control signals (input) comes from an arduino.
The problem that i am having with my 1st attempt is that when i put in my power source (for the h bridge) even 5v now to test, the transistors are getting warm.. and i cant find out why?? (even with no motors or inputs connected).
I left out the diodes from the schematic as i thought they are for dc motors which might spin and cause feed back power, but that shouldnt happen with steppers? are these necessary?
Only thing that i can think of is that both the halves of the h bridge are "enabled" and power is shorting directly from the pnp to the npn. ( even with no motor connected)
Could this maybe be from the smaller transistors picking up voltage and enabling the 4 tip-122 and tip-127 transistors??
Please if any one could give me some assistance, I dono if the info i have given is sufficient, but it will be greatly appreciated!
Thanks
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