I have the following configuration H Bridge:

enter image description here

I have not added any diodes for kick back protection. I have one 100 uF capacitor across 3 V supply and ground. The Collector of Q1 and Q2 are connected to same 3 V (Not visible in the picture). The DC motor is used to drive a gear in one direction and stopped when stalls. And will be moved back when required. It is not a dynamic to and fro movement. There will by a few 10s of ms of delay between two motor drive inputs.

What are the weak points in the design? Please suggest any improvements towards safeguarding the motor drive circuitry and rest of the board.

Battery is Alkaline, 1.5 V x2 = 3V, 1400 mAh. I have read article on Diode purpose in H bridge here, but still i have to verify this BJT circuit as well.


Just place a diode across your motor ( Parallel to your inductive load i.e. motor)

Back Emf can easily be handeled with a diode as shown in figure

Moreover as per your requirement, just compare your transistors with the switches in the figure and place diode as shown in figure

I hope this will solve your problem. :)

  • \$\begingroup\$ I am looking for challenges with out the diodes. I may be naive but because of my drive conditions simplicity, I am bothering you to see whether it is really required. \$\endgroup\$ – User323693 May 22 '15 at 4:51

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