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Author Topic: Need help on DC voltage conversion  (Read 2438 times)

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Offline dsesmgTopic starter

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Need help on DC voltage conversion
« on: October 02, 2009, 04:27:03 AM »
Hi,
I have a beam sensor and I am trying to find a way to convert  the voltage of this beam sensor to around 4volts(plus or minus half a volt)

The sepicifcation of this beam sensor can be found here.
http://www.santec.co.kr/pro_09_03c.htm
But, the contents are not written in English.
Please referece only the pictures in that link.

I translated the content of the specification.
* Type : NPN
* Detection type : Direct reflection type
* Connection type : Code withrawal type  
* Detection distance(max) : 500mm
* Operating voltage : 12~24VDC +or- 10% Ripple P-P below 10%
* Current consumption : Below 35mA
* Iluminance : Under sun light(10,000Lx),
              Under illuminate light(3,000Lx)
* Max inflow current : 100mA
* Residual voltage : Below 1.0V(at 100mA inflow current)
 Below 0.4(at 16mA inflow current)
* Response time : below 1ms
* Moderation resistance : Above 20Mohm(DC500V mega)
*Three wires connection : blue(signal), brown(+), black(-)

When I power this beam sensor, I used 12vdc power supply.
I measured how much voltage is comming out from the beam sensor by measuring it with a multimeter.
The multimeter shows 75.6mV when the beam is not interrupted.
When the beam is interrupted, the multimeter shows 0.816v.
I assume if use 24vdc power supply, the voltage comming from the beam sensor would be the twice this current reading. But, it is not enough.
I need 4 volts from this beam sensor when the beam is interrupted.
Is there any way to get 4 volts ?
Please help me.

Offline billhowl

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Re: Need help on DC voltage conversion
« Reply #1 on: October 02, 2009, 05:37:11 AM »
For the Spec, it look like the output is NPN open collector, what you need to do is put a pull up resistor of 10K from the output to +5V and you will able to get TTL voltage When the beam is interrupted.

Offline dsesmgTopic starter

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Re: Need help on DC voltage conversion
« Reply #2 on: October 02, 2009, 06:20:33 AM »
Hi, thank you so much for your advise.
I was unsure of how to put the pull up resistor to the beam sensor.
Could you take a look at this drawing and tell me whether this connection is ok?
http://www.flickr.com/photos/34955071@N02/3974464256/#sizes/o/
If I am wrong, please correct me,
thank you.

Offline billhowl

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Re: Need help on DC voltage conversion
« Reply #3 on: October 02, 2009, 07:22:52 AM »
Your beam sensor have to power by 12V supply, so only your signal line is pull up to 5V line by the 10K resistor

Offline dsesmgTopic starter

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Re: Need help on DC voltage conversion
« Reply #4 on: October 02, 2009, 07:31:07 PM »
Hi, thank you very much for your answer.
I really appreciate it.
Now, I have a voltage regulator(MC7805).
I also want to try to test using a voltage regulator and a resistor.
Please take a look at this drawing.
http://www.flickr.com/photos/34955071@N02/3975261515/#sizes/o/
So, i use the 12v to convert it to 5v and then i limit the current to get the 4v in the end.
Is this OK?

Offline billhowl

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Re: Need help on DC voltage conversion
« Reply #5 on: October 03, 2009, 03:38:02 AM »
The center pin of the 7805 must be connected to ground.
The sensor is open collector output mean if you pull up to 5V and you will get 5V output, if you need to have 4V output then you pull up at 4V.

Offline Soeren

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Re: Need help on DC voltage conversion
« Reply #6 on: October 03, 2009, 10:44:18 AM »
Hi,

Why do you need 4V?
It's a digital output, so there's no need use an A/D-C if that's what you had in mind.
This should do:

R3 and R4 could be changed for higher or lower current. As it is, approximately 22.5mA goes through the resistors, so to keep the potential, what you connect to the output shouldn't draw more than 1mA max., or the resistors should be changed.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
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Offline dsesmgTopic starter

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Re: Need help on DC voltage conversion
« Reply #7 on: October 03, 2009, 07:24:40 PM »
Thanks a lot. I appreicate it.
I will try that schematics.
Have a good day.

Offline dsesmgTopic starter

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Re: Need help on DC voltage conversion
« Reply #8 on: October 07, 2009, 03:51:18 AM »
Quote
Now, I have a voltage regulator(MC7805).
I also want to try to test using a voltage regulator and a resistor.
Please take a look at this drawing.
http://www.flickr.com/photos/34955071@N02/3975261515/#sizes/o/
So, i use the 12v to convert it to 5v and then i limit the current to get the 4v in the end.
Is this OK?
I tried this but, it is not working.
I connected 7805's middle pin to Gnd but it is not working.
Please take a look at this picture.
http://www.flickr.com/photos/34955071@N02/3989165107/#sizes/o/
I measured the output from the MC7805 and the multimeter shows exactly 5v. But, the meter measured 75.6mV when beam is not interrupted and measured 0.816v when the beam is interrupted which is the same as before. I probed the red circle area when I measure the voltage.
Could you advise me which part should be corrected in the circuit?
« Last Edit: October 07, 2009, 04:07:20 AM by dsesmg »


Offline Soeren

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Re: Need help on DC voltage conversion
« Reply #10 on: October 07, 2009, 01:47:09 PM »
Hi,

Please take a look at this picture.
http://www.flickr.com/photos/34955071@N02/3989165107/#sizes/o/
I measured the output from the MC7805 and the multimeter shows exactly 5v. But, the meter measured 75.6mV when beam is not interrupted and measured 0.816v when the beam is interrupted which is the same as before. I probed the red circle area when I measure the voltage.
Could you advise me which part should be corrected in the circuit?
From that photo, absolutely nothing is clear - please post a schematic instead.
And please post a link to the pdf-datasheet instead of images too small to make out.
We can only help if you give us the data in a readable form and a link is so much easier to post anyway.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline dsesmgTopic starter

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Re: Need help on DC voltage conversion
« Reply #11 on: October 07, 2009, 07:59:59 PM »
oh. i'm sorry for that.
Actually, the hompage of that beam sensor is not written in English. So it is quite difficult to find it by searching it in there.
Please let me ask how to post PDF file or a link.
I should have asked this long before...

The schematic is below.
http://www.flickr.com/photos/34955071@N02/3991189371/#sizes/o/
« Last Edit: October 07, 2009, 08:12:43 PM by dsesmg »


Offline Soeren

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Re: Need help on DC voltage conversion
« Reply #13 on: October 09, 2009, 10:32:19 PM »
Hi,
Please let me ask how to post PDF file or a link.
Find the link you want to post.
Right click and then "copy link address" (or something similar, it differs between browsers).
In the post, click the "insert hyperlink" button (the globe picture).
Then press Ctrl-V (with the cursor in between the "url" tags.

If you didn't get it to work with the schematic I posted, then the circuit, the sensor or the assembly is bad/dead.
Measure around in the circuit and post your findings, then we can find which it is.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline dsesmgTopic starter

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Re: Need help on DC voltage conversion
« Reply #14 on: October 10, 2009, 03:51:13 AM »
Hi, How are you?
Quote
Hi,

Quote from: dsesmg on October 07, 2009, 06:59:59 PM
Please let me ask how to post PDF file or a link.

Find the link you want to post.
Right click and then "copy link address" (or something similar, it differs between browsers).
In the post, click the "insert hyperlink" button (the globe picture).
Then press Ctrl-V (with the cursor in between the "url" tags.
Thanks a lot.


Quote
If you didn't get it to work with the schematic I posted, then the circuit, the sensor or the assembly is bad/dead.
Measure around in the circuit and post your findings, then we can find which it is.
The wiring wasw wrong. Now, I can get the 5v. After putting 2Mega ohm, I could get 4v.
I will practice more, thank you .

Offline walkercreations

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Peter Walker
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