Wall clocks, mp3 players, electronic sensors, and special devices use 1.5V battery (cell) as power source. We sometimes forgot to buy or replace the battery but no worries because we can design circuits that can convert higher DC voltages to useable 1.5V.
The following electronic circuits are possible schematic of 1.5V power sources or regulators.
Simple 1.5V power supply
Around 20mA maximum output current, good in low power application like wall clocks.
 |
| simple power supply |
R- 220 ohms 1/4W
D - 1N4001 or similar diode
LED - 3mm or 5mm red LED
C - 4.7uF electrolytic capacitor
DC - 4V to 6V DC source
Improved 1.5v power supply
Transistor Q increase the maximum output current up to 200mA
 |
| Improvised power supply |
R- 220 ohms 1/4W
LED - 3mm or 5mm red LED
C - 4.7uF electrolytic capacitor
Q - 2N2222, 9013 or similar NPN transistor
DC - 4V to 5V DC source
Using LM317 regulator
Output current is up to 1000mA (can be higher) and input voltage is 4V to 15V DC. Best voltage regulation and efficiency compared to previous power supplies. Output voltage is based on the values of R1 and R2 (see LM317 calculator for possible R1 and R2 combinations).
 |
| LM317 power supply |
Part List:
R1 - 200 ohms 1/4W
R2 - 40 ohms (39 ohms) 1/4W
C - 4.7uF electrolytic capacitor
LM317 regualtor IC
DC - 4V to 12V DC source
Improved 1.5v power supply
ReplyDeleteSir, can I use Transistor Q 9014 or BC548 and can i use three Transistor Q parallel to increase its current capacity.
my DC source is unregulated 5V to 7.5V at 800mA
Paralleling the 3 transistor you mentioned is good idea and its theoretically correct. Actually I have done that with some of my projects (not in this one).
ReplyDeleteJust try paralleling but just make sure that if you are using 7.5V supply just limit the output current to 250mA max to avoid overheating(9014 or BC548); and 400mA for 9014 and 250mA for BC548 when 5V source is used.