Stepper Motor Circuit with IC 4027

This stepper controller circuit shown here can used to control the unipolar stepper motor,which has 4 coils . The stepper controller circuit can drive for a motor current of up to about 500 mAmp/Winding by suitable heat sinks for the SL-100. directsinks In higher currents power transistors seem 2N3055 can be used as darlington pair along with SL-100. All diodes are used to protect back current the transistor from transients.

Stepper Motor Circuit with IC 4027 Circuit diagram :

Remark. 

• You may be able to substitute any standard (2N3055) power transistor for Q1-Q4 or get IC type UL to modify for transistor.
• Every time in move the motor put signal the STEP line is pulsed, the motor moves one step.
• Switch S1 for changes the motors direction

Read More..

Digital Stop Watch Using NE555 Timer IC

This is s design of digital stop watch circuit that built around timer IC LM555 and 4-digit counter IC MM74C926 with multiplexed 7-segment LED display. This is the figure of the circuit.


MM74C926 consists of a 4-digit counter, an internal output latch, NPN output sourcing drivers for common cathode, 7-segment display and an internal multiplexing circuitry with four multiplexing outputs. The counter advances on negative edge of the clock. The clock is generated by timer IC LM555. The circuit works off a 5V power supply. It can be easily assembled on a general-purpose PCB. Enclose the circuit in a metal box with provisions for four 7-segment displays, rotary switch S1, start/stop switch S2 and reset switch S3.

For operation this circuit is explanation in the next. First, reset the circuit by pressing S3 so that the display shows ‘0000.’ Now open switch S2 for the stop watch to start counting the time. If you want to stop the clock, close S2. Rotary switch S1 is used to select the different time periods at the output of the unstable multi vibrator (IC1). This circuit is powered by 5V DC. That power supply can take from regulator power supply. You can read in this site about the regulator that can be used.

Read More..

Inverter Circuit Using IC 4069 Discussed

Please read the previous post for the continuation...

Hi Aliman,
I am interested to follow the output stage exactly as given in your square wave design. I want you to include all the MOSFETs - NP as well as PN along with the buffer transistors and their base resistors.


The logic is very simple, if the output stage is responding and working well with the signals from the IC 4069, it should do the same with the signals from the 4017 ICs, after all both the designs are producing square waves (our design is producing a chopped one though.)

The voltages that you are getting are absolutely fine and the differences are too trivial to produce any effect on the circuit, moreover, very unlike the transistors, for MOSFETs its the voltage that matters and not the current and thats why the buffer transistors become very important and must be included.


I think it will be also important to include 10K resistors from the base of each buffer transistor to GROUND.

I wont be able to help you with the MOSFET types, as I myself am not quite knowledgeable with these devices, but the above modifications should hopefully set things in the right order.

Thanks and Best Regards.

Hi Swagatam, what if I replace the buffer transistor with one that has a higher collector current. Would that make a difference ?

 Also you mentioned adding 10K resistors, because there already is a 10K resistor from the 4069 to the base of the buffer transistor, so you want me to add another 10K from the Base to ground ,  correct ?

I dont have any PNP mosfets right now. But if this output stage works with the Square wave circuit , with some minor changes our PWM circuit should work also.

Sincerely Ali 

Hi Aliman,

I think we better stick to the tested design given below, so lets follow the circuit as given in your square wave design... we can always modify it once it starts working.

Thats correct... The 10K resistor from the base of the transistors to the ground will ensure that every time the diodes stop conducting the base receives a ground or a low logic level and switches OFF completely.

Yes..of-course, if it starts working then the issue gets over and we wont need to include the PNPs.

Best Regards.


Continued HERE,

Read More..