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  1. C

    unexpexted performance of unipolar stepper driver.........

    I am using the attached circuit. By providing 0 to Enable point, it starts moving the motor in both directions, some steps to one and some to other direction without any more input and stops by providing 1 to enable. I want to move one by one step. Please guide.
  2. C

    Making switching NPN with PNP

    I have tried the following attached circuit in the same structure having fixing the components on a paper card. The real schematic is also attached. I am testing the switching of TIP42 by attaching  + probe of voltmeter with collector of TIP142 and
  3. C

    Making switching NPN with PNP

    There is a small circuit schematic attached where I am using voltage regulator 7812. I input 24VDC and 12VDC comes out from OUT pin. I want to make switch off & on NPN transistor with 12VDC buy using PNP transistor before NPN. And I will use PC printer port to provide the 1 & 0 pulse of...
  4. C

    TIP142 Stepper motor driver

    Now following stepper driver is successful to run the steps of motor. But there is a problem that the transistors turn hot very quickly. What is problem here. I think the resistor is small. Is it?
  5. C

    TIP142 Stepper motor driver

    There is complete circuit in this[//url] thread. I have post all info about it. Ok now I will try fixed resistor. I am only wonder why the transistor not switched on to run the motor.
  6. C

    TIP142 Stepper motor driver

    Thanks guys, I have try to install 1K variable resistor and have adjust it to many values. But still the motor does not move any step. Is there any way to troubleshoot the circuit?
  7. C

    TIP142 Stepper motor driver

    Now, I have try this circuit with 24V DC, 1.7Amp power supply. But still the motor does take any step (forward or backward). I think the value of resister is very much big. What it should be? And I could not understand your formula. Now how can I use it with above power supply?
  8. C

    TIP142 Stepper motor driver

    Thanks, how about the value of resistor?
  9. C

    TIP142 Stepper motor driver

    I am going to build following circuit to run stepper motor using TIP142. So is there any need to change any thing in this circuit? The schematic of circuit is attached with this post.
  10. C

    Increasing the DC 5V 250 mA adopter volt & amp.

    How about to use big resistor to drop the 220v AC to 24v AC then use bridge rectifier to convert it to DC?
  11. C

    Increasing the DC 5V 250 mA adopter volt & amp.

    I want transformerless power supply with 24V 2 Amp and I think any existing cell phone battery adopter can do it for me. I have an DC adopter (5V 250 mA) and want some changes in the circuit to get my desired volt & amp. You can review the circuit of any of your adopter, as most peoples has...
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