Thursday, October 23, 2014
1 3V DC to 12 2V DC Regulator Power Supply
In addition, the power supply circuit is also equipped with over-current protection or shield against belebih flow. Power supply circuit is very simple, but the quality is quite good, made her basiskan regulator IC LM723 is a pretty legendary.
Description:
R2 to set the output voltage. The maximum current is determined by R3, over-current protection circuit inside the LM723 to detect the voltage on R3, if it reaches 0.65 V, the voltage output will be off her. So the current through R3 can not exceed 0.65 / R3 although output short-circuit in his.
C3 and C4 are ceramic capacitors, as much as possible directly soldered to the PCB, this is because the LM723 is prone to oscillation that is not cool.
LM723 works with 9.5V input voltage to 40 V DC and the LM723 can generate its own current of 150mA when the output voltage is not more than 6-7V under input voltage.
Specifications:
Output (value estimated):
Vmin = (R4 + R5) / (R5 * 1.3)
Vmax = (7.15 / R5) * (R4 + R5)
Imax = 0.65/R3
Max. Power on R3: 0.42/R3
Min. DC Input Voltage (pin 12 to pin 7): Vmax + 5
Component List:
B1 40V/2.5A
C1 2200uF (3300uF even better)
C2 4.7uF
C3 100nF
C4 1NF
C5 330nF
C6 100uF
Green LED D1
D2 1N4003
F1 0.2A F
F2 2A M
IC1 LM723 (in a DIL14 plastic package)
R1 1k
R2 Pot. 5k
R3 0.56R/2W
R4 3.3k
R5 4.7k
S1 250V/1A
T1 2N3055 on a heatsink 5K / W
TR1 220V/17V/1.5
Sunday, October 5, 2014
IC 723 2N3055 13 2V 40A Power Supply Unit
THE HEAVY CURRENT carrying connections are shown in bold in Fig 1. The mains input passes through an EMC filter, protection fuse F1 and ON/OFF switch S 1 to transformer TI. The secondary output of TI is rectified by D I but cannot pass through open relay contacts RL1a. To start the PSU switch, S2 is operated allowing limited current to pass via R1 to slowly charge the reservoir capacitor C1. As C1 charges, the RL1 a pulls in closing the relay contacts and shorting out R1 and S2 placing the PSU in the ON state.
Voltage regulator IC1 is the popular 723. A 7.2V reference on IC 1:6 is fed to non-inverting ICI:5. This is compared with a sample of the PSU output voltage via RI3, RI4 and R15 to inverting input at ICI:4. The 723 can source 150mA at ICl:10, so transistor TR2 acts as a Darlington driver for the pass transistors TR3 to TR7 inclusive. Resistors R21 to R25 are current sharing resistors and the voltage across them is proportional to the current drawn by the PSU load.
When the current through R21 reaches 8A (i.e. a total PSU current output of 40A) the voltage across R11 and R12 is 0.88V and is tapped from R I I to bias a transistor inside IC1 which robs IC1: 10 of some current, forcing the PSU into a current limiting mode.
