|
| If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|||||||
|
|
Thread Tools | Display Modes |
|
#1
March 14th 11, 09:58 AM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
Difference between 1/4W and 1/2W resistors?
For a 5V input (USB - LED), should I use 1/4W or 1/2W? -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.37.3 ^ ^ 17:56:01 up 3 days 4:17 1 user load average: 1.12 1.13 1.14 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa 
|
|
#2
March 14th 11, 10:14 AM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
On 14/03/2011 09:58, Man-wai Chang wrote:
For a 5V input (USB - LED), should I use 1/4W or 1/2W? It depends on how current is going to be drawn through them. Jacquie.
|
|
#3
March 14th 11, 10:34 AM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
On 14/03/2011 18:14, Jacquie wrote:
On 14/03/2011 09:58, Man-wai Chang wrote: For a 5V input (USB - LED), should I use 1/4W or 1/2W? It depends on how current is going to be drawn through them. I only knew V=IR. How do I apply this principle to this W spec? -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.37.3 ^ ^ 18:31:01 up 3 days 4:52 0 users load average: 1.00 1.02 1.06 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa
|
|
#4
March 14th 11, 11:10 AM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
For a 5V input (USB - LED), should I use 1/4W or 1/2W?
It depends on how current is going to be drawn through them. I only knew V=IR. How do I apply this principle to this W spec? And Power (W) =VI -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.37.3 ^ ^ 19:06:01 up 3 days 5:27 0 users load average: 1.05 1.06 1.08 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa
|
|
#5
March 14th 11, 11:13 AM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
On Mon, 14 Mar 2011 18:34:25 +0800, Man-wai Chang rearranged some
electrons to say: On 14/03/2011 18:14, Jacquie wrote: On 14/03/2011 09:58, Man-wai Chang wrote: For a 5V input (USB - LED), should I use 1/4W or 1/2W? It depends on how current is going to be drawn through them. I only knew V=IR. How do I apply this principle to this W spec? P = VI If the LED drops 2V (typical) then you have to size the resistor value to also drop the same difference at the current you want to run the LED at. Let's say, 20ma.. 5V - 2V LED = 3V resistor. 3V/20ma = 150 ohms. 20ma * 3V = 60mW so a 250mW resistor is sufficient in this case. You have to substitute the voltage drop and desired current for the LED that you want to use.
|
|
#6
March 14th 11, 11:52 AM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
20ma * 3V = 60mW so a 250mW resistor is sufficient in this case. You
have to substitute the voltage drop and desired current for the LED that you want to use. What if I used a 1/2W resistor instead of a 1/4W (250mW?)? Would it reduce the current too much? -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.37.3 ^ ^ 19:51:01 up 3 days 6:12 0 users load average: 1.01 1.07 1.11 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa
|
|
#7
March 14th 11, 12:41 PM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
On 14/03/2011 11:52, Man-wai Chang wrote:
20ma * 3V = 60mW so a 250mW resistor is sufficient in this case. You have to substitute the voltage drop and desired current for the LED that you want to use. What if I used a 1/2W resistor instead of a 1/4W (250mW?)? Would it reduce the current too much? It's only the resistance value of the resistor and the load that determines the current drawn, not the wattage of the resistor. Jacquie.
|
|
#8
March 14th 11, 04:06 PM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
It's only the resistance value of the resistor and the load that
determines the current drawn, not the wattage of the resistor. Then why are resistors (in that shop at least) classified resistors by W? -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.37.3 ^ ^ 00:01:01 up 3 days 10:22 0 users load average: 1.01 1.03 1.05 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa
|
|
#9
March 14th 11, 04:15 PM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
On 14/03/2011 16:06, Man-wai Chang wrote:
It's only the resistance value of the resistor and the load that determines the current drawn, not the wattage of the resistor. Then why are resistors (in that shop at least) classified resistors by W? So you can choose the correct wattage for it's intended use. Jacquie.
|
|
#10
March 14th 11, 04:46 PM
posted to alt.comp.hardware.pc-homebuilt
|
|||
|
|||
|
Difference between 1/4W and 1/2W resistors?
So you can choose the correct wattage for it's intended use.
Let me review your replies first.  -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.37.3 ^ ^ 00:41:01 up 3 days 11:02 0 users load average: 1.08 1.05 1.07 不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA): http://www.swd.gov.hk/tc/index/site_...sub_addressesa
|
| Thread Tools | |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| LEDs in Mouse & Resistors | Jeff | Dell Computers | 1 | September 4th 06 01:04 PM |
| LEDs in Mouse & Resistors | Bruce | Homebuilt PC's | 1 | September 4th 06 08:01 AM |
| Messed up CPU Cache resistors | John Whitworth | Overclocking AMD Processors | 2 | August 20th 05 10:53 PM |
| What's the difference between these? | Ollie T | Homebuilt PC's | 4 | January 2nd 04 08:59 AM |
| What's the difference | Tom Swift | Dell Computers | 7 | December 13th 03 01:47 AM |
Linear Mode
