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pn 2222 substitue & Iadj. in the design

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rajaram04

rajaram04

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Hello sir

here is the circuit diagram

LM317-voltage-regulator-digitally-selected-output.png

here is the link where i found it

https://www.circuitstoday.com/few-lm317-voltage-regulator-circuits


sir i want a commonly available substitute for pn 2222 transistor , is it possible to apply a bc548 or something like that ????????

in the formula relating above circuit

Vout = 1.25V (1 + (R2/R1)) + I adj R2.

how to decide Iadj. ????????????????

please help . . thanks
 

I think BC 549 should do well...548 too
 

and... Iadj is decided by R5, R6, R7 and R8 and which combination of them is passing current because the transistor below it is conducting.

Brian.
 

betwixt said:
and... Iadj is decided by R5, R6, R7 and R8 and which combination of them is passing current because the transistor below it is conducting.

Brian.
Click to expand...





and what about the value of R4 actually ? thet we have to decide or it is constant ?
 

As you can read on your schematic, R3 and R4 set amplitude, do the math and read the datasheet for more explanation. It is just like when you use the lm317 without the transistors.
 
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PA4TIM said:
As you can read on your schematic, R3 and R4 set amplitude, do the math and read the datasheet for more explanation. It is just like when you use the lm317 without the transistors.
Click to expand...



ohh if so then thats very simple then in that case

well please tell me one thing about this lm 317 etc that is it possible to drive out diffrent voltages at same time ??

i did practicals & found no design suitable but as some people adviced me so i am asking if there any circuitry possible ??

please comment
 

Different voltages at the same time. Means what?
 

This schematic is a programmable powersupply. By switching transistors you can get a "preset" voltage and use a microprocessor to control it.

Do you know something about electronics ? I do not think so. Come down to earth and tell us what you want to make.

A regulator that gives more voltages at the same time is not possible. You need 1 regulator for 1 voltage. So if you need 5 voltages, you need 5 regulators.
 

Re: pn 2222 substitue & Iadj. in the design

PA4TIM said:
This schematic is a programmable powersupply. By switching transistors you can get a "preset" voltage and use a microprocessor to control it.

Do you know something about electronics ? I do not think so. Come down to earth and tell us what you want to make.

A regulator that gives more voltages at the same time is not possible. You need 1 regulator for 1 voltage. So if you need 5 voltages, you need 5 regulators.
Click to expand...





ya ya that too i was arguing with people telling me but still they are on the same sentence , i still saying its not , logically no way out for such a process

- - - Updated - - -

FvM said:
Different voltages at the same time. Means what?
Click to expand...




sir actually i want to design a power supply which can provide voltage levels at diffrent output pints say a 3v 5v 9v 12v & so on & searching for a compact one but failed so making diffrent power supplies for diffrent levels with expansion in area :cry:
 

PA4TIM said:
Sorry, but I have no clue about what you want to ask.
Click to expand...



actually i was searching for a unit which can provide voltage levels at diffrent points but at same time so found this design & posted here for general idea so as to make my base about what i am doing for the aim , nothing else . .
but no way i got , i ll have to make diffrent regulated power units using lm317 as you said
 

OK, please be more specific, my crystal ball stays dark.

- how many outputs you need
- and what voltages you need.
- how much current per output
- do you need current limmiting or other protection like crowbars or OVP ?
- Powered from mains or DC-DC
- linear or switching ? (probably linear if you want the LM317
 

hmm yaa linear with output of 3v,5v,9v,12v,15v with 500mA current . .
powered from mains with ovp (if possible)

sir what is crowbar ?
 

Re: pn 2222 substitue & Iadj. in the design

https://en.wikipedia.org/wiki/Crowbar_(circuit)

You need a transformer from mains to something like 15V , a big enough heatsinc, diode bridge, switch, busses, fuse, caps, resistors, extra diodes and some other small stuff, a 7815, 7812, 7809, 7805 and some 3V regulator. You can daisy chain the voltages if you do not use them all at once. Otherwise better use preregulation or powertransistors over the 78XX.
For instance a big enough transistor (18-9=9V x 0.5A = 4.5W dissipation, without that it would be: 18V-5V=13x0.5=-6.5W in that poor 7805.) and a 9V zener on the base followed by the 7805
OVP can be done by a VDR and a fuse, or a powerzener but with fixed voltage you do not use a settable OVP like in some lab bench supplys.
 

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