Multiple power supplies from single bench supply

[afz23]

I often require different power supplies for my PCBs,
I need to generate following regulated voltages from a single bench supply:
+8V/2A
-5V/25mA
+15V/200mA
+2V/30mA
-1V/10mA
Kindly help me design this PCB,which takes a single
input and genetates multiple supply points as required above.

 

[chuckey]

The difficulty is the 2A@+8V and 25mA @ -5V. if you use say a 0, +20V setting on your PSU, the 2A will have to flow into the -5V regulator. The easiest way is to get a + to - volt convertor, this will neatly separate the + and - voltages. So set your PSU to +15V with a +15V to -5V converter. Then just use variable stabiliser chips to get your various voltages the +8V one will have to be on a heat sink.
Frank

 

[KlausST]

Hi,

There are dc/dc converter ICs available. Doing step down, step up and inverting.
The manufacturers usually have interactive selection guides at their internet pages to find the right one.
At the datasheets you may find information on how to adjust to your needs and layout considerations. Read them carefully.

Klaus

 

[afz23]

LM317 IC is well known IC for regulating positive voltages,whereas LM337 is used for regulating negative voltages
Can we use LM317 in place of LM337 in the circuit attached?or what changes have to be made in the circuit to use LM317
in both places.

 

[Vbase]

In this circuit you cannot use 317 in place of 337, there are no changes that will do the trick.

 

[BradtheRad]

A 555 timer IC can drive a negative charge-pump, to give you your negative (-5V) supply. See:

http://www.electronicecircuits.com/electronic-circuits/555-negative-voltage-power-supply-circuit

The negative supply is referenced to 0V ground. This is the principle which makes it usable as an independent negative supply.

With a resistive divider across -5V, it will provide your -1V supply.

 

[afz23]

BradtheRad, if I use stabilized positive voltage as input to the circuit based on IC 555,will it provide stabilized negative voltage? Can it be directly used to gate bias circuit,for biasing transistor?

 

[hobbyckts]

can you provide the Input supply range?

 

[BradtheRad]

BradtheRad, if I use stabilized positive voltage as input to the circuit based on IC 555,will it provide stabilized negative voltage? Can it be directly used to gate bias circuit,for biasing transistor?

Output voltage will start to drop when you place enough load on it.

Voltage regulation can be devised in a number of ways, if you wish. A 5V zener diode is the easiest and simplest method.