Basic Voltage Question
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Posts: 46,084
Tipically EACH led requires about 10~20 mA current. Then for 5~6 VDC
supply you will need 220 ~ 330 Ohm resistor to EACH led in the
bargraph. You don't need a 2 V regulator.
ACJacques
Forbesits@y... wrote:
>
> Hello,
>
> Thanks again for all the help everyone has provided in the past!!!
>
> I'm using a bar graph led display. Each pin requires 2V. How do I
> turn 5V into 2V or 6V into 2V. I tried several resistors to reduce
> current but each led shows a bright orange instead of red which leads
> me to believe that too much voltage is being used. I tried 470 and
> also 10K resistors.
>
> I have a 5V voltage regulator, do I need a 2V one also?
>
> Thanks for any adivce,
> FS
supply you will need 220 ~ 330 Ohm resistor to EACH led in the
bargraph. You don't need a 2 V regulator.
ACJacques
Forbesits@y... wrote:
>
> Hello,
>
> Thanks again for all the help everyone has provided in the past!!!
>
> I'm using a bar graph led display. Each pin requires 2V. How do I
> turn 5V into 2V or 6V into 2V. I tried several resistors to reduce
> current but each led shows a bright orange instead of red which leads
> me to believe that too much voltage is being used. I tried 470 and
> also 10K resistors.
>
> I have a 5V voltage regulator, do I need a 2V one also?
>
> Thanks for any adivce,
> FS
Comments
Thanks again for all the help everyone has provided in the past!!!
I'm using a bar graph led display. Each pin requires 2V. How do I
turn 5V into 2V or 6V into 2V. I tried several resistors to reduce
current but each led shows a bright orange instead of red which leads
me to believe that too much voltage is being used. I tried 470 and
also 10K resistors.
I have a 5V voltage regulator, do I need a 2V one also?
Thanks for any adivce,
FS
>I'm using a bar graph led display. Each pin requires 2V. How do I
>turn 5V into 2V or 6V into 2V. I tried several resistors to reduce
>current but each led shows a bright orange instead of red which leads
>me to believe that too much voltage is being used. I tried 470 and
>also 10K resistors.
<---Assuming 10 ma per LED, , simply use Ohm's law to figure the required
resistance to produce the drop.
You want to drop 5 volts to 2, which is 3 volts. Therefore R = E/I or R=
3/.01 = 300 ohms). 270 or 330 ohms is the closest value and perhaps close
enough. Although you didn't mention how precise that 2 volt figure needs to
be).
Ken
Ken
Ken Arck
http://www.ah6le.net
Amateur Radio Station AH6LE
[url=palace://stables.xsia.com:9998]palace://stables.xsia.com:9998[/url]
aka Ph's horse
http://www.al-williams.com/wd5gnr/basiccir.htm which offers the "why" of
this stuff.
Regards,
Al Williams
AWC
* Floating point math for the Stamp, PIC, SX, or any microcontroller:
http://www.al-williams.com/awce/pak1.htm
>
Original Message
> From: Forbesits@y... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=V-yD2Q-opQfOtzl0PzcI6i2U7SfzGb1PnbnLt96C_3IAURujMv4T0wOboQSdHF-juYEY5pFGhLFg]Forbesits@y...[/url
> Sent: Wednesday, November 29, 2000 6:42 PM
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Basic Voltage Question
>
>
> Hello,
>
> Thanks again for all the help everyone has provided in the past!!!
>
> I'm using a bar graph led display. Each pin requires 2V. How do I
> turn 5V into 2V or 6V into 2V. I tried several resistors to reduce
> current but each led shows a bright orange instead of red which leads
> me to believe that too much voltage is being used. I tried 470 and
> also 10K resistors.
>
> I have a 5V voltage regulator, do I need a 2V one also?
>
> Thanks for any adivce,
> FS
>
>
>