Designing a power supply with variable DC/AC voltage

[akamilrazak]

Hi guys.. I need help from u all profesional designer..
do u have any design of a power supply..

the voltage from 240 Vac to transformer 18 V Ac.
i want to change the voltage using lm7815 and lm7915. it for +15 V and -15V.
can u give me a design circuit for this circuit.. any simplest design..

 

[Awarapunshee]

voltage regulator 7815

The 78 or 79-series need not much circuit, only a capacitor or two as shown in https://www.elecfree.com/circuit/power-supply/power-supply-regulator-15v-15v-1a-by-ic-7815-7915/

If you need variable than go to


ENJOY!

 

[akamilrazak]

variable 30v

thank you very much for your help.. that really helps a lot.. i also need to design the variable ac voltage for 0-30 Vac.. do have an idea for that? basic one.. i maybe use the 240/15 v transformer..

 

[Awarapunshee]

how to design variable dc power supply.

Go for the 2nd option above

 

[akamilrazak]

variable dc 30 v

no... if we want to design a power supply that can produce variable ac voltage, can we use regulator? i guess it was totally a different circuit.. maybe need to use thyristor.. i really need help on that.. designing a variable 0-30 AC voltage supply.. anything similar can also help.. basically it about to design a variable voltage supply.

 

[Awarapunshee]

variable resistor 0-30 volts

no... if we want to design a power supply that can produce variable ac voltage, can we use regulator? i guess it was totally a different circuit.. maybe need to use thyristor.. i really need help on that.. designing a variable 0-30 AC voltage supply.. anything similar can also help.. basically it about to design a variable voltage supply.

Ofcourse you cannot use these regulator for Variable AC PSU (I have missed Vac), You can use Variac (A Rotary mechanism on a Toroidal Transformer), OR a Triac control circuit can do the job but with some noise etc, OR an Auto Transformer with multiple loops (in this case you have variable pure AC but with a steps not linear).

 

[akamilrazak]

dc-30v

thanks very much for that tips, can u help in giving any basic circuit for designing the circuit for that.. it is really difficult to build one my self..

 

[pranam77]

lm7815 variable

Use this circuit after the filtering stage and adjust the Variable resistor till you get 30 volts or any other volts you need at the output. Good luck. Hope it helps.

 

[akamilrazak]

variable using 7815

this is for dc supply.. can i get one for ac supply variable...

 

[lats]

variable 0-30 voltage circuit

Change your subject put AC over there instead of DC

 

[pranam77]

lm7815/lm7915 power supply schematic

Hi guys.. I need help from u all profesional designer..
do u have any design of a power supply..

the voltage from 240 Vac to transformer 18 V Ac.
i want to change the voltage using lm7815 and lm7915. it for +15 V and -15V.
can u give me a design circuit for this circuit.. any simplest design..

You had asked for DC supply using 7815 for + 15 volts and 7915 for - 15volts which are used for DC applications, and I have given a simpler design for variable positive supply for your request. Good luck.