USB DrDAQ PWM

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M.Yasser
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USB DrDAQ PWM

Post by M.Yasser » Sat Aug 25, 2012 12:09 pm

Hi,
I'm trying to use PWM1 and PWM2 of the USB DrDAQ writing my own programs using the SDK. To be able to control motors using H-bridges, I need to raise the voltage level of the PWM signal from about the 0-2V to meet the logic level 0-5V of the H-bridges. so I need some information about the o/p circuit of the PWM. Is it safe to connect a pull-up resistor to the o/p?
Are there any alternative solutions?
Regards.

Martyn
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Re: USB DrDAQ PWM

Post by Martyn » Tue Sep 04, 2012 8:31 am

You will need to amplify the output of the DrDAQ it is a low level signal, pull-up's wont work.
Martyn
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M.Yasser
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Re: USB DrDAQ PWM

Post by M.Yasser » Wed Sep 05, 2012 7:28 pm

Hi,
PWM supposed to be a digital signal (on/off) not an analog signal isn’t it?
Analog signals need amplifier if they are small signals; digital signals need a level converter.
I need to know the output circuitry of USB DrDAQ to apply a suitable conversion circuit to it.
Regards.
Yasser

Pico Stuart
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Re: USB DrDAQ PWM

Post by Pico Stuart » Fri Sep 07, 2012 11:04 am

Hi There,

One option would be to use an NPN transistor. Simple and effective.The silicon transistor was invented in 1954 and has been considered one of the greatest inventions in the history of technology. In terms of using the PWM function of DR Daq you could connect the base to the PWM OUTPUT( signal voltage), choose a value of resistor suitable for connecting to the +Ve rail ( 1 K ), connect the emitter to negative (ground) the result collector output will be inverted.

Dr Daq PWM.jpg


Hope this helps,

Have a great weekend.

Kindest regards,

Stuart
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M.Yasser
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Re: USB DrDAQ PWM

Post by M.Yasser » Fri Sep 07, 2012 11:19 am

Hi Pico Stuart,
Thank you for your reply. You gave me a nice inexpensive solution.
Although I wanted to understand the o/p circuitry of DrDAQ.
Thanks again.
Yasser

Martyn
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Re: USB DrDAQ PWM

Post by Martyn » Tue Sep 11, 2012 10:09 am

We do not divulge our IP so we can't provide you with this detail.
Martyn
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M.Yasser
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Re: USB DrDAQ PWM

Post by M.Yasser » Tue Sep 11, 2012 5:18 pm

no problem.. thanks any way.

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