วันอาทิตย์ที่ 18 สิงหาคม พ.ศ. 2556

วงจร IC LM317

     หลายคนคงจะเคยเจอปัญหา เวลาที่เราจะทดลองโปรเจคสิ่งประดิษฐ์ต่างๆที่เราคิดค้นขึ้นมา แล้วไม่มี Power supply 
     ไม่ต้องคิดมากครับนึกถึงนี่เลยครับถ้าหากต้องการ Power Supply ที่สามารถปรับแรงดันได้ตามต้องการ 

LM317 Voltage

LM317 เป็นไอซีเรกูเรเตอร์รักษาระดับแรงดันตามที่ต้องการ เหมาะกับการสร้างพาวเวอร์ซัพพลายจ่ายแรงดัน 1.25-30V กระแสไม่เกิน 1.5A  ( ใช้ไอซี LM317 ) วงจรง่ายๆ ไม่ยุ่งยาก แถมยังประหยัดตังค์อีกต่างหาก

ศึกษาจาก Data sheet ก่อนนะครับ
http://www.steveselectronics.com/files/LM317T_National.pdf


การต่อวงจรใช้งานก็ง่ายๆครับ




ส่วนนี่ก็เป็นวงจรป้องกันเมื่อเกิดการลัดวงจรครับ



หลายคนก็คงเกิดคำถามอีกว่าเราสามารถคำนวณหาค่า R1,R2 ได้อย่างไร

สูตร

Vout    =    1.25 * ( R2/R1 + 1 )

และสุดท้าย เป็น ค่า R ที่ผ่านการคำนวณมาแล้ว เพื่อความสะดวกในการทำ Power supply สำหรับท่านครับ

1.43V    R1 = 470, R2 = 68
1.47V    R1 = 470, R2 = 82
1.48V    R1 = 370, R2 = 68
1.51V    R1 = 330, R2 = 68
1.51V    R1 = 390, R2 = 82
1.52V    R1 = 470, R2 = 100
1.53V    R1 = 370, R2 = 82
1.56V    R1 = 330, R2 = 82
1.57V    R1 = 270, R2 = 68
1.57V    R1 = 470, R2 = 120
1.57V    R1 = 390, R2 = 100
1.59V    R1 = 370, R2 = 100
1.60V    R1 = 240, R2 = 68
1.63V    R1 = 330, R2 = 100
1.63V    R1 = 270, R2 = 82
1.64V    R1 = 390, R2 = 120
1.64V    R1 = 220, R2 = 68
1.65V    R1 = 470, R2 = 150
1.66V    R1 = 370, R2 = 120
1.68V    R1 = 240, R2 = 82
1.71V    R1 = 330, R2 = 120
1.71V    R1 = 270, R2 = 100
1.72V    R1 = 220, R2 = 82
1.72V    R1 = 180, R2 = 68
1.73V    R1 = 470, R2 = 180
1.73V    R1 = 390, R2 = 150
1.76V    R1 = 370, R2 = 150
1.77V    R1 = 240, R2 = 100
1.81V    R1 = 270, R2 = 120
1.82V    R1 = 150, R2 = 68
1.82V    R1 = 330, R2 = 150
1.82V    R1 = 180, R2 = 82
1.83V    R1 = 390, R2 = 180
1.84V    R1 = 470, R2 = 220
1.86V    R1 = 370, R2 = 180
1.88V    R1 = 240, R2 = 120
1.89V    R1 = 470, R2 = 240
1.93V    R1 = 330, R2 = 180
1.93V    R1 = 150, R2 = 82
1.94V    R1 = 270, R2 = 150
1.96V    R1 = 390, R2 = 220
1.97V    R1 = 470, R2 = 270
1.99V    R1 = 370, R2 = 220
2.02V    R1 = 390, R2 = 240
2.03V    R1 = 240, R2 = 150
2.06V    R1 = 370, R2 = 240
2.08V    R1 = 330, R2 = 220
2.10V    R1 = 220, R2 = 150
2.12V    R1 = 390, R2 = 270
2.13V    R1 = 470, R2 = 330
2.16V    R1 = 330, R2 = 240
2.16V    R1 = 370, R2 = 270
2.19V    R1 = 240, R2 = 180
2.23V    R1 = 470, R2 = 370
2.25V    R1 = 150, R2 = 120
2.27V    R1 = 270, R2 = 220
2.27V    R1 = 330, R2 = 270
2.29V    R1 = 470, R2 = 390
2.29V    R1 = 180, R2 = 150
2.31V    R1 = 390, R2 = 330
2.36V    R1 = 270, R2 = 240
2.37V    R1 = 370, R2 = 330
2.40V    R1 = 240, R2 = 220
2.44V    R1 = 390, R2 = 370
2.50V    R1 = 470, R2 = 470
2.57V    R1 = 370, R2 = 390
2.61V    R1 = 220, R2 = 240
2.65V    R1 = 330, R2 = 370
2.66V    R1 = 240, R2 = 270
2.73V    R1 = 330, R2 = 390
2.74V    R1 = 470, R2 = 560
2.75V    R1 = 150, R2 = 180
2.76V    R1 = 390, R2 = 470
2.78V    R1 = 270, R2 = 330
2.78V    R1 = 220, R2 = 270
2.84V    R1 = 370, R2 = 470
2.92V    R1 = 180, R2 = 240
2.96V    R1 = 270, R2 = 370
2.97V    R1 = 240, R2 = 330
3.03V    R1 = 330, R2 = 470
3.05V    R1 = 390, R2 = 560
3.06V    R1 = 270, R2 = 390
3.06V    R1 = 470, R2 = 680
3.08V    R1 = 150, R2 = 220
3.13V    R1 = 220, R2 = 330
3.14V    R1 = 370, R2 = 560
3.18V    R1 = 240, R2 = 370
3.25V    R1 = 150, R2 = 240
3.28V    R1 = 240, R2 = 390
3.35V    R1 = 220, R2 = 370
3.37V    R1 = 330, R2 = 560
3.43V    R1 = 270, R2 = 470
3.43V    R1 = 390, R2 = 680
3.43V    R1 = 470, R2 = 820
3.47V    R1 = 220, R2 = 390
3.50V    R1 = 150, R2 = 270
3.54V    R1 = 180, R2 = 330
3.55V    R1 = 370, R2 = 680
3.70V    R1 = 240, R2 = 470
3.82V    R1 = 180, R2 = 370
3.83V    R1 = 330, R2 = 680
3.84V    R1 = 270, R2 = 560
3.88V    R1 = 390, R2 = 820
3.91V    R1 = 470, R2 = 1000
3.92V    R1 = 220, R2 = 470
3.96V    R1 = 180, R2 = 390
4.00V    R1 = 150, R2 = 330
4.02V    R1 = 370, R2 = 820
4.17V    R1 = 240, R2 = 560
4.33V    R1 = 150, R2 = 370
4.36V    R1 = 330, R2 = 820
4.40V    R1 = 270, R2 = 680
4.43V    R1 = 220, R2 = 560
4.44V    R1 = 470, R2 = 1200
4.46V    R1 = 390, R2 = 1000
4.50V    R1 = 150, R2 = 390
4.51V    R1 = 180, R2 = 470
4.63V    R1 = 370, R2 = 1000
4.79V    R1 = 240, R2 = 680
5.04V    R1 = 330, R2 = 1000
5.05V    R1 = 270, R2 = 820
5.10V    R1 = 390, R2 = 1200
5.11V    R1 = 220, R2 = 680
5.14V    R1 = 180, R2 = 560
5.17V    R1 = 150, R2 = 470
5.24V    R1 = 470, R2 = 1500
5.30V    R1 = 370, R2 = 1200
5.52V    R1 = 240, R2 = 820
5.80V    R1 = 330, R2 = 1200
5.88V    R1 = 270, R2 = 1000
5.91V    R1 = 220, R2 = 820
5.92V    R1 = 150, R2 = 560
5.97V    R1 = 180, R2 = 680
6.04V    R1 = 470, R2 = 1800
6.06V    R1 = 390, R2 = 1500
6.32V    R1 = 370, R2 = 1500
6.46V    R1 = 240, R2 = 1000
6.81V    R1 = 270, R2 = 1200
6.92V    R1 = 150, R2 = 680
6.93V    R1 = 330, R2 = 1500
6.94V    R1 = 180, R2 = 820
7.02V    R1 = 390, R2 = 1800
7.10V    R1 = 470, R2 = 2200
7.33V    R1 = 370, R2 = 1800
7.50V    R1 = 240, R2 = 1200
8.07V    R1 = 330, R2 = 1800
8.08V    R1 = 150, R2 = 820
8.19V    R1 = 270, R2 = 1500
8.30V    R1 = 390, R2 = 2200
8.43V    R1 = 470, R2 = 2700
8.68V    R1 = 370, R2 = 2200
9.06V    R1 = 240, R2 = 1500
9.58V    R1 = 330, R2 = 2200
9.77V    R1 = 220, R2 = 1500
9.90V    R1 = 390, R2 = 2700
10.03V    R1 = 470, R2 = 3300
10.37V    R1 = 370, R2 = 2700
10.63V    R1 = 240, R2 = 1800
11.25V    R1 = 150, R2 = 1200
11.44V    R1 = 270, R2 = 2200
11.48V    R1 = 330, R2 = 2700
11.67V    R1 = 180, R2 = 1500
11.83V    R1 = 390, R2 = 3300
12.40V    R1 = 370, R2 = 3300
12.71V    R1 = 240, R2 = 2200
13.75V    R1 = 330, R2 = 3300
15.31V    R1 = 240, R2 = 2700
16.25V    R1 = 150, R2 = 1800
16.53V    R1 = 270, R2 = 3300
16.59V    R1 = 220, R2 = 2700
18.44V    R1 = 240, R2 = 3300
19.58V    R1 = 150, R2 = 2200
20.00V    R1 = 220, R2 = 3300
23.75V    R1 = 150, R2 = 2700
24.17V    R1 = 180, R2 = 3300
28.75V    R1 = 150, R2 = 3300