DC motor in parallel port

[ibstk]

parallel port opto isolator

Hello..

I need a circuit to interface with PC's parallel port. I want to make a speed control DC motor. I've implemented the closed loop control using delphi. It'll send signals (high or low) for parallel port's pins (data) thru control trackbar.

The program and parallel port are not the problem. I need a simples analog circuit for control the speed of motor DC depending of signal in the pins.

Sorry for the english...
Regards.

 

[unlving]

dc motor via parallel port and diode

Here is the schematic of LED interface! Just remove the LEDs and rezistors and wire all to the DC motor so when you put high on another data pin it will turn faster!

 

[sertorius]

parallel port dc motor circuit

what about problems from back-emf etc when the motor stops? can this cause damage?

you could use an opto-isolator or something if it does.

how much current is available from parallel ports anyhow?

 

[batdin]

parallel port motor delphi

You can use a simple DAC followed by an amplifier (suppose DC motor cannot be powered by TTL outputs).DAC could be a set of resistors.
BUT if you want to do the thing in the right way try to change the output of just one pin so that the duty cycle is changed and the driver can be a switch transistor with low losses compared to the case when an analogue amplifier is used.

 

[ibstk]

parallel port opto isolator schematic

Here is the schematic of LED interface...

Hi, the interface's not problem. I need a simples digital/analog circuit for control of DC motor.

... you could use an opto-isolator or something if it does. how much current is available from parallel ports anyhow?

Hi sertorius, I think is 250mA. I'm not sure. Use opto-isolator is very important.

You can use a simple DAC followed by an amplifier
(suppose DC motor cannot be powered by TTL outputs).DAC could be a set of resistors.

Hi batdin, do you have a schematic?

BUT if you want to do the thing in the right way try to change the output of just one pin so that the duty cycle is changed and the driver can be a switch transistor with low losses compared to the case when an analogue amplifier is used.

yah, I can this too by serial port or one pin in parallel port. But I need a schematic for control DC motor using A/D, amplifier ou transistor switch. The communication (serial or parallel ports) I know.

 

[nford]

parallel port opto isolation schematic

what about problems from back-emf etc when the motor stops? can this cause damage?

you could use an opto-isolator or something if it does.

how much current is available from parallel ports anyhow?

To use the parallel port is is essential to use some type of buffer(eg optoisolator, 74XX240, etc) to prevent damage to the port from drawing excess current. From this you need some method of converting the digital signal to a signal which will regulate the speed of a motor (eg. a DAC, PWM, etc). Depending on the method with which this signal is created and the motor you are using, you might need to amplify the signal or use a motor driver (eg. SGS THompson LM293, Texas Instruments SN754410, etc)

With you motor and back-EMF, there are two ways of fixing it : you can either reverse bias a diode across the motor leads. Otherwise you can put a cap between the motor leads to smooth the signal.

Hope this info helps

 

[unlving]

12v motor parallel port

nford, give us schematic

 

[batdin]

control dc motor with parallel port circuit

Here you are!
The accuracy is not perfect but you don't need perfection anyway.
5-bit DAC should be enough.If not,add some more resistors in the same way but don't expect linearity to be good.
The circuit is designed for 12V DC motor.If it is 5V,change R2 to 13 KOhms and reduce Vcc to 9V .
Good luck!

 

[nford]

parallel port dc motor diode

nford, give us schematic

Scrap my previous post - Batdin's schematic is a more elegant solution than I presented .

Im one of those crazy people who goes for a complicated solution when something like the previous schematic is all that is needed.

 

[pitstryke]

Hi. I need schematic diagram for a circuit that can attach 6 dc motors. Thanks.