I want to add a few amps to the output of a stepper motor driver (bipolar 4 wire) with out modifying the interns of the driver.
MY QUESTION IS BEFORE I START I WANT TO ASK IF THERE IS A PROBLEM WITH MY IDEA BELOW AND OR MY SCHEMATIC.
My idea is pull ground +24 and the 4 wires that go to the motor and make them switch some transistors like so. Again I want to know if there is a problem here with component values and what not. I only ask because I tend to dew stupid stuff and i do not want to blow this up.
simulate this circuit – Schematic created using CircuitLab
PS: sorry for caps I keep getting marked down for not having a clear question.
Best Answer
The rearranged version of your schematic looks like
simulate this circuit – Schematic created using CircuitLab
The problems have already been mentioned by jippie, and rearranging the schematic shows that the lower four transistors (Q8,Q9,Q6,Q11) are inverted (collector<->emitter).
Also note that even if the level of the bridge supply was the same as the control level you would need to use one resistor for each base because a common one would make both upper/lower transistors conduct simultaneously.
One solution you can use to control the bridge from two logic level control signals is shown in A simple H-Bridge design