One of my friend demanded to
design such a project where there is two different DC power supply ,we need to
have un interrupted output , this circuit is designed around 48 Vdc , both
power supply input mentioned in the circuit are 48v-1 & 48v-3
, both voltages were then combined by the diode D1 & D2 , it is then down converted
by the R2 (330R, 5W) to make it in the input Rang of LM317 IC 2 , with the R24
& R25 it output will be near 15 V , then after it 7805 IC were used for
fixed 5V supply for the whole circuit. Initially if power applied to the
circuit ,Relay K1 will energize due to opto-coupler direct connected to the incoming
both power supply while triggering transistor T2, IC C & D will be energized when relay K1 will activated
, actually both gates of IC C & D are set as a timers , when power applied to
the IC both timers will start , first timer ( C ) will will trigger T3 realy K2
will energized ,the contact of this relay (6 & 4 ) will be disconnected by
resulting Q1 off , here Q1 kept off by the R28 ,will be on by the R30 , the Relay
( 200 Amps) which is (SV2-1) is normally closed ( ON) ( with no power ) if Q1 enabled it will
results relay activated & the contacts will be separated power will be disconnected,
on the other the relay (SV2-3) will be activated by
Q2 from relay K3 driven by the T4 , & T4 will be activated by IC1 D
( other timer). if timer run T4 will activated relay K3 , contacts (8 & 4 ) will make , Q4 will
be on , capacitor C3 will remain the relay k2 on till capacitor discharged.
Buzzer SG1 will be on when relay K1 activated. Threshold voltage level be adjusted
by R1
