regarding amplification

[gollapudi]

for giving bias for the LM 675(operational amplifier) , i need a dc supply of +30 and -30 volts. but this is not avilable in my laboratory. by using transformers and rectifiers is is possible to get the required +30 and -30 volt dc voltage. please give me the suggestion and give the necessary diagrams.
please help me.
thanking you sir.

 

[gollapudi]

sir,
i am using LM675 for the purpose of amplification,but it needs +/- 30 volt dc upply, but in my lab only +/- 15 volts is avilable. please suggetion how to get the +/- 30 volt dc voltage.

 

[Syncopator]

... by using transformers and rectifiers is is possible to get the required +30 and -30 volt dc voltage

Yes. You need to construct a dual voltage supply. There are innumerable such circuits available on the internet.

 

[gollapudi]

i tried in internet for getting the circuit diagram, but i could n't. please give me the circuit diagram for the dual 30 volt dc supply by using transformer , rectifier and using filtering capacitor.

 

[Syncopator]

Here's one way to do it.

The current rating of the transformer's secondary should be twice the d.c. required.



If you have difficulty finding a transformer with a 48V secondary, you can do it with two x 24V.

The current rating of the transformers' secondaries should be 1.6 x the d.c. required

 

[gollapudi]

i tried the second circuit. i used an auto transformer before the two transformers for the purpose of varying the voltage. i have used a 1000 micro farad,160 volt capacitor, but when i varied the voltage ,after getting 17 volt dc across the capacitors , both capacitors blown. please suggest me the correct rating of the capacitor to use, and what may be the reason for the blown of the capacitor.

 

[0by1]

my doubt is how you are using transformer for +15V DC?

for LM 675 supply range is 6v to 60v or +/- 30v.
better you can use DC-DC converter ( 15v to +/- 24v) like this
https://www.recom-international.com/pdf/Econoline/RY.pdf

 

[Syncopator]

The capacitors should have a voltage rating of rather more than the expected d.c. 50V ones, or more, would be suitable.