[atomgonuclear]

ok well I am trying to make my DIY stepper driver and I think I finally have the supplys but I need some help because im confused

from what I understand the parrallel port is a TTL transistor so it can sink current and source current

I have elected to get 2N3906 PNP transistors

Collector/base voltage :40
collector/emmitter Voltage :40
emitter/base voltage: 5v
power dissapation 300MW
Vceo breakdown 25V
and
Hfe at 10ma :50

I have 4 rectifier diodes that can handle up to 1000v and 80 amps pulsed or 2.5 amps continuous

4 5.1 volt zener diodes

and a bunch of power MOSFETS all rated at Vgs :10-20 volts for full on power
and up to 9 amps continuous current.


Now my question is howto hook this up to the parrallel port..... right now i am really confused

I have drawn a diagram to help


I want to drive the MOSFET gate voltages with the transistors because the parrallel port only puts out +5 volts max

So using an external 10 volt supply(or 20 volt supply), I will hook this up to the collector of the transistor and base of the MOSFET

the base of the transistor will be hooked up to the +5 volt logic from the motherboard with a resistor in between and a zener diode incase there is any voltage spikes.

The mosfet's alone I think can handle the reverse current from the inductance but you can never be too shure, they are rated at over 200 volts.

Will this circuit work???

how can I figure out the voltage that is going to be coming from the base of the transistor into my computer, I am not worried about the current because I think MOSFETs gate only draws a couple of nanoamps correct??

Thanks for the help in advance
the thing I am just really confused about is the voltage going through the base of the transistor and howto control it or figure it out.... is it proportional to the collector and emitter voltage?

I have attached a diagram too

[mugabe]

look for unipolar stepper driver to get insight of what should be done to drive them correctly. Then see the international rectifier page for applications notes especially where it is describing driving mosfet .

[pminmo]

Take a look at my website, maybe you will find some help and understanding there.