[SOLVED] power supply circuit

1n4148 is a zener diode??

1N4148 is a zener diode?
what is main application area of this diode?
what can be the possible use of this diode in making multiple output power supply?
(multiple o/p channel means -12v,12v,5v,24v,36v at the same time)

Re: 1n4148 is a zener diode??

Hi,

Each electronic part has it's own datasheet. And so has the 1N4148.
It answers a lot of your questions. Read through it.
There is no way around it. We professionals need to read them, too. A lot of datasheets.

Klaus

Re: 1n4148 is a zener diode??

1N4148 is probably the most common small signal diode on Earth. Probably 100 companies make them and have data sheets for them, it shouldn't be too hard to search for one of them.

No - it isn't a Zener diode, it's a small signal silicon diode.
It can be used for multitudes of purposes in many parts of a power supply and most other kinds of electronic equipment. We would have to see a schematic to tell exactly what it did in a specific design.

Brian.

Re: 1n4148 is a zener diode??

Hello RAHUL_KUMAR,
To further add to what Brian has told you, 1N4148 diodes are not suitable as rectifier diodes, say using them in a bridge
rectifier, half-bridge etc, to rectify any AC voltages. Their small current rating would, in most cases, prevent this.
They can be used as voltage droppers though.
eg. Say you need 3.6 volts from a 5 volt supply: You can add 2 of them in series and that will drop it to the required voltage.
Each will drop approximately 700mV. But the current must not exceed their individual maximum rating.
General purpose diodes are better suited where higher currents are required for rectification and voltage dropping requirements.
If you're wanting to design and/or make an switch-mode type of power supply, those diodes will come in handy. Mainly due to
their high switching frequency.
Regards,
Relayer

1S880 diode ? Application and use.

what is the use of this diode in parallel to filter capacitor? ( filter capacitor after bridge rectification for power supply)
cathode of this diode is input to base pf power transistor TIP122.

(this is implemented in circuit of power supply of multiple output.)
didnt get much help from google

Re: 1S880 diode ? Application and use.

Hi,

please learn to ask elaborated questions.
Read the datasheet.
Show the circuit you refer to.

Klaus

multiple output -12,+12,+5,24 and 36v from top to down .
i want to know the transistor operation part of the circuit diagram means how the bc557,ic 639 ,tip 122 and lm337 are linked and how the lower circuit is linked from upper regulated output.

I merged three closely related threads.

To reduce confusion, I suggest to redraw the circuit using correct component symbols for voltage regulators. In my view, it would be also preferred to sort the voltage nodes (at least the fixed +/-12 V) in usual order starting with most positive voltage on top.

It's also helpful to see the connected transformer circuit, and at least for the LM317 reference pin the connection on the right side.

Hi,

regarding "IS880"

I assume the correct name is "1N5880" a 60V zener diode. Obsolete.
It limits / regulates the voltage....at the output (emitter) of the bjt.

Klaus

KlausST said:

Hi,

regarding "IS880"

I assume the correct name is "1N5880" a 60V zener diode. Obsolete.
It limits / regulates the voltage....at the output (emitter) of the bjt.

Klaus

Click to expand...

i am not able to get which diode is this,..in very close look 15 or 1S is written and bellow 880(it is also a guess,coz nt visible clearly) is written.
the circuit is copied from a hardware.

Hi,

Can´t you take a photo in macro shot mode?

Klaus

The diagram is certainly confusing when it contains wrong symbols but answering the question: the '880' whatever prefix is a pre-regulator for the LM317. The odd thing is the LM317 will regulate far better than the Zener diode and TIP122 so I can only guess the reason they exist is to drop the incoming voltage below the 40V maximum the LM317 can tolerate.

Brian.