Do you have a schematic?
Help with transistors - PWM and LED prosject
-
2nd May 2012 06:21 PM #1thastian
Help with transistors - PWM and LED prosject
Hey everyone
I need someones help, and i'm very thankful for all help. I have searched the net for hours without finding out the answer to my question.
I have a simple diagram. I have a LED light (6W, 320mA), a driver, and a Audrino board.
The driver gives power to the LED light, between the driver and the LED is an unknown transistorm and from the transistors base it goes to the PWM output (5V, 40mA) of the Audrino board.
What i need help for is figuring out the circut between these 3 compenents. The driver, LED and audrino. I dont know what transistor i shuld use and what kind of resistor.
The idea is that the Audrino board is dimming the LED light with PWM thro the transistor.
Can anyone help me with this prosject?
And sorry about my bad english =P
-
2nd May 2012 07:39 PM #2ronv
0
-
3rd May 2012 05:10 AM Thread Starter #3thastian
Here is a schematics i put together fast. Please let me know if something is unclear.
schematics.png0
-
3rd May 2012 09:32 AM #4alec_t
Is your 'driver' specifically for the LED you have? Does it have current limiting? Can you post a link to its specification?
0My circuit designs should be regarded as experimental. Although they work in simulation, their component values may need altering or additional components may occasionally be necessary when the circuit is built. Due safety precautions should be taken with any circuit involving mains voltage or electrostatic-sensitive components.
Alec's First Law:-
Every problem has a solution (given the right information and resources).
-
3rd May 2012 09:44 AM Thread Starter #5thastian
The driver is made specifically for the LED yeah. It's part of a package. All the specification i got on the driver is what i have provided.
The driver and the led comes preassambled from the vendor, but the driver is exsternal. I can open the driver and the LED amature to look for more infomation on what components there is.0
-
3rd May 2012 10:55 AM #6alec_t
The LED spec implies that its drive voltage is 6W/320mA = about 18V. In the circuit you posted the transistor is connected as a high-side switch and would need at least 18.6V on its base to turn on. The Arduino can't provide that directly, so it would be better IMO to use a low-side switch instead. To avoid loading the Arduino significantly I think a MOSFET would be the transistor of choice. Something as per the attached perhaps?
0My circuit designs should be regarded as experimental. Although they work in simulation, their component values may need altering or additional components may occasionally be necessary when the circuit is built. Due safety precautions should be taken with any circuit involving mains voltage or electrostatic-sensitive components.
Alec's First Law:-
Every problem has a solution (given the right information and resources).
-
17th May 2012 03:15 PM Thread Starter #7thastian
Thank you for your help and schematics. Will try this.
If i change the LED load to 4W (making the drive voltage about 12.5) can i still use the same MOSFET?
And is there a similar MOSFET with pins?
Thank you very much for the help =)0
-
20th May 2012 07:20 PM #8alec_t
Sorry for the late reply.
The same MOSFET should be ok, but almost any N-MOSFET specified as 'logic-level input' and with a low Rdson (say <0.1Ω) will do. However, if your LED driver is made specifically for a 6W/320mA load then it may fry your new LED unless a current-limiting resistor or other limiter is used.0My circuit designs should be regarded as experimental. Although they work in simulation, their component values may need altering or additional components may occasionally be necessary when the circuit is built. Due safety precautions should be taken with any circuit involving mains voltage or electrostatic-sensitive components.
Alec's First Law:-
Every problem has a solution (given the right information and resources).
-
22nd May 2012 10:38 AM Thread Starter #9thastian
Thanks for the reply.
Can i use this MOSFET? http://no.farnell.com/international-...220/dp/8657360
The 4W LED lights have the lower wattage driver =)
Thanks again0
-
22nd May 2012 10:50 AM #10alec_t
No, that's not a 'logic level' FET so the Arduino can't fully turn it on.
0My circuit designs should be regarded as experimental. Although they work in simulation, their component values may need altering or additional components may occasionally be necessary when the circuit is built. Due safety precautions should be taken with any circuit involving mains voltage or electrostatic-sensitive components.
Alec's First Law:-
Every problem has a solution (given the right information and resources).
| Tags |
| Similar Threads | ||||
| Thread | Starter | Forum | Replies | Last Post |
| Need help with finding millicandellas and lumens ratings for flexible LED ribbon | essare | General Electronics Chat | 0 | 13th July 2010, 08:16 PM |
| Need some help with a circuit and don't know where to begin! | Zandor_Vorkov | Electronic Projects Design/Ideas/Reviews | 6 | 9th December 2003, 01:03 PM |
| Help with pbc layout and schematic matching...MAX712... | eyevancsu | Electronic Projects Design/Ideas/Reviews | 3 | 29th September 2003, 08:15 PM |
| I need help with transistors | Briskability | General Electronics Chat | 7 | 31st July 2003, 06:38 AM |
| I need help with transistors and a power supply, posted schm | darkbrace | Electronic Projects Design/Ideas/Reviews | 5 | 30th June 2003, 12:58 PM |