Circuit Power Supply MJ15004
From
circuit in figure below. the AC 220 volts when through a T1-transformer then will be AC voltage 36V. The F1-fuse size of 2 Amperes. The SW1 is ON/OFF switch of this projects.
This 36 volts is Average the voltage. When through the D1-bridge rectifier then will be C1 and C2 are filter to smooth a fluctuating signal(AC Volts).
When push the S1-power switch ON, Both capacitors C1 and C2 will discharges through the R1-resistor.
The input voltage of this regulated circuit is volts across C1 and C2 will equal to 50 volts. And is entered at emitter of Q2. To output next. The circuit in section R2, C3 and ZD1 are the regulated circuit of +15 volts to the circuit of IC1, IC2 and IC3.
The
circuit of IC1 all will be the pulse circuit. wide mod as say above, both C4 and R4 will be RC that create frequency that have value about 20 kHz. In character at pin 13 to ground. The working of both transistor within TL 494 will works in the Single-end Operation type.
The both transistor in TL494 can pull current up to 400 mA which can drive base of Q2. But will see that VC1 and VC2 have value of 40 volts only.
Which this circuit has voltage high up to 50 volts, if connect directly to them Must damaged certainly.
Therefore, the need for security, Q1-
transistor (BD139) to also drive the Q2 . Both R12, R13 that parallel together, as limiter base of Q2 will not over than 250 mA decisively.
View IC1 back again. They R8, R9 and C5 between pin 2 and pin 3 that will be network that be editor Q2 work with narrow pulse before (are Q2 partially ON”) so can reduce pull of the output current.
When push
switch SW1 normally to working. then at pin 3 of TL494 will be have a low voltage. So, cause output of the within comparator circuit are “High”. The Q2 will be on. But if the voltage at pin 3 have a higher value in first time. (because C5) The Q2 will be partially no. Then voltage at pin 3 will reduce slowly normal state. (because they will be discharge through R8)