12V and 9V Power Supply Please

12v to 9v resistor

Sir,

I need a circuit of a power supply with regulated +12V and +9V output.Max current 5A


----Power Supply------>[regulator--12V]__>__[regulator--9V].....>

12v to 9v

You need a 5A rated transformer. I suggest a 12-0-12 transformer. This shall let you use a full wave rectifier of 2 high current diodes (I do not remember the diode number...Do not use the 1N4007)

You must follow this with a 4400micro farad shunt capacitor filter or a pi Filter.

The LM7812 (12v) and LM1705 (5v) ICs are rated for 100mA max with heat sink.

The LM 317 is rated for 1.5 A. This can let you select the output voltage by manupulating an externally connected potential divider network.

However if you are keen on 5A, use the LM338 IC. This is similar to the 3 pin LM317. but costs 4 times more and comes in a steel package.

Hope this might help you...

Added after 2 minutes:

You can get the circuit for the LM338 and LM317 IC in the typical application section of their respective datasheet with typical values and formula to calculate the values.

These are linear voltage regulators and the difference of the input and the output voltages are dessipated as heat. So you must use a heat sink.

dc to dc 12v to 9v circuit lm317

This is for 12V-30A, you can modify it for 5A using only one or two transitors ... if you use three transistors maybe you can't need of heat sink ... you have to study the thermal resistence of transistor ...

**broken link removed**

For 9V-5A you can use a similar aproach, using the LM317 or LM7808 (and add diode between GND terminal of LM7808 and GND of circuit)

leomecma

resistor 12v to 9v

LM317 has a 1.5A limit and 7808 has a 100mA limit.

9v power supply circuits

LM78L08 (TO92) has 100mA of limit, but LM7808CT (TO220) has 1A, some makers has 7809 too. You can improve the current add bypass transistors like this:

h**p://www.zen22142.zen.co.uk/Circuits/Power/1230psu.htm

Using this approach the power current is supply by transistors, and I suggested exactly same thing for 12V and 9V.

leomecma

12v to 9v regulator

Yuo don't write anything about your application, but maybe a switching power supply is good enough. Iif yes, try 'simple switcher' from national semiconductor.

www.national.com

The efficiency is much better as linear regulators.
felix1200

9v power supply circuit

If I will connect it to the 12V regulator and 9V regulator, should I make the transformer 24V insted of 12V power supply.

[1.5A - 2A will do]


[ 24V ps] -----[12V regulator]----[9V regulator]----> two regulated output 12V and 9V

resistor 12v - 9v

Simply I want a Supply for my project which can supply regulated 12V and 9V.

9V for a small circuit (TV Show Buzzer) and a 12V for my 12V lamp and buzzer connected in my cicuit (through relay)

How much current do you think for my circuit? ( a cicuit with 4 lamp and 1 buzzer)

---
Another thing: Can I connect a resistor to the 12V so that I won't have a problem getting a 9V output. Insted of regulating 9V from 12V supply.


THANK YOU

power supply 9v lm317

Does the A will heat up more because it is in series with B?

I get my ieda from the PIC Programmer circuit. (supply part)

What other possible thing will happen?

Can you give me circuits like this please.\]

12v na 9v

After little bit of googling I found a chip which satisfy ur needs.

follow this link: **broken link removed**

Please note that I've not tried this one.

cya

Randika K

Added after 3 minutes:

Hay, I've found some more chips.

LM338T
LM323T

After some googling (i.e www.gogle.com .... ;-) ) you will find the data sheets.
Then do your design...

cya

Randiak K

1230psu

If you are happy with ≈2A use for 12V the LM350 ( https://www.onsemi.com/pub/Collateral/LM350-D.PDF ) in its basic configuration (picture below), and for 9V the LM317 (or even the LM317L, if 9V requires less than 100mA) in the same configuration. In both cases use R1=240Ω, for 12V R2=2kΩ, and for 9V R2=1.5kΩ ..
Lower the unregulated voltage to as low as 15-16V (under full load). This will prevent the regulators from generating to much useless heat.
Also, don't connect regulators in series; there is no need for that; connect them both directly to 16V unregulated voltage ..

Regards,
IanP

9v powersupply without power transformer circuits

Hi
you need 12V and 9V with 5A current. it 105Watts power supply.
you can see this page for power supply design.

www.powerint.com