pull-up resistor R Series

[tiho]

Hi

I am using NI PCI 7833R. I would like to raise the voltage from 3V to 5V. I have configured one DIO pin as an output and I have connected to it one resistor equal to 10kOhms. One end of the resistor is connected to the output of the PCI board and the other end of the resistor is connected to an external power supply (5V). I have expected to achieve 5V on the output but without success. Could you please give me an advise. I would like to generate a sqare signal from 0 to 5V.

[Alex.T]

You could use a MOSFET transistor to switch the voltage at the output of the PCI Digital Output. Here's a simple level switching circuit.

[tiho]

Hi

I have used connector 2 DIO0 of the NI PCI 7833R board. I have applied a pull-up resistor equal to 5kOhms thus increasing the output voltage from 3.3V to 5V buy without success. After changing the pin with DIO1 I have achieved 5Volts. I have connected one dc motor to DIO1 and GND. I have made the following application attached to this mail. I have generated pwm signal setting pulse width = 3000 and pulse period 3500. The frequency on the oscilloscope is around 200 Hz. The dc motor doesn't work. Could you please give me an advise. May be the current of the NI board is not enough. How to raise the output current?

[Alex.T]

Cool. I just checked out the specifications and it states that this card is capable of generating 5V signals, so you've probably found a pin capable of doing it!

Can you show me the datasheet of the motor you're using?

I assume you're using a stepper motor. You do need to supply a lot more current to it than is capable from the driving pin of the PCI card to get a motor turning. At a push you could probably drive a very small hobby motor directly from a power rail, but that's all. Motors require current proportionally to their size; larger motors require more current. Stepper motors the size of an apple for example require about 1A to get turning. If you check out the specification of the card, you'll see that there's no way of driving that kind of current directly from an output pin.

To increase the drive capacity, the motor needs to be connected to a Bridge Circuit, or a stage interface for the motor. If you look up the motor specifications you should see some examples on how to construct an appropriate interface with it.

[crossrulz]

You really should be using a digital buffer that will allow a voltage change.  Something like a SN74LVCC4245 should work.

[tiho]

Hi

I am sending the datasheet of my dc motor (Maxon DC Motor - 118396). I saw that the starting current of the motor is 660 mA. I don't know exactly the current of the NI PCI 7833R board. For achieving 5V I am using an external supply of 5V and 3A, connected to one of the ends of the pull-up resistor. What do you think about the VI application. Is it OK?

[GerdW]

Hi tiho,

if you would read the manual of your PCI7833 you would know that it is specified to source/sink 4mA on its DIO pins...

You need a motor driver - any reasonable MOSFET will do!

[tiho]

Hi

I have tried to use L298D chip but till the moment without success.

[GerdW]

Try further to be successful!

🙂

[tiho]

Hi

I am sending a scheme how I am connecting my dc motor but till now it is not working.