0-30V Stabilized Power Supply

[audioguru2]

Can I double the 2N3055 and use the BD139 off the PCB?

Yes, if each 2N3055 has its own 0.33 ohm emitter resistor.

 

[Big zee]

how can i make it the best PS by adding -30 volt to the circuit and dual linear pontesiometer for the voltage

so it will be -30 . 0 . +30

can the IC power the -30 to add IC4 ?

 

[audioguru2]

how can i make it the best PS by adding -30 volt to the circuit and dual linear pontesiometer for the voltage

so it will be -30 . 0 . +30

can the IC power the -30 to add IC4 ?

There is no IC4 in the circuit.
Nothing in the project is grounded.

If you want a negative supply then use one of these projects and use the positive output as 0V. Then the "0V" output is the negative output.

Then make a second project to produce the positive output voltage with its "0V" used normally as 0V and the positive output is the positive output.

 

[Big zee]

And use the same circuit?
Caps trnsistiors and diodes ?

What about the transformer ? And the bridge ?

And the output +30 0 0 -30
The 2 zeroes conected to same point ?
+30 0 -30
Not
+30 0 0 -30

Thx.

 

[audioguru2]

And use the same circuit?
Caps trnsistiors and diodes ?
What about the transformer ? And the bridge ?

Make two completely separate circuits. Even separate transformers and separate bridge rectifiers.
The first circuit can make 0V to +30V and the second circuit can make 0V to -30V.

And the output +30 0 0 -30
The 2 zeroes conected to same point ?
+30 0 -30
Not
+30 0 0 -30

Yes, you can connect the positive output of the second one to the 0V of the first one.

 

[audioguru2]

Could you provide calculation, what mains AC input fuse should I use (for 230V, 50Hz country)?

When the output current is 3ADC then the power is 38V plus 2V of rectifier drops x 3A= 120W.
Since your mains is 230VAC then 120W uses 230V/120W= 1.92A AC. Use a 2.5A fuse.

Furthermore, someone in this forum recommended ("P.S. use PTC! They limit the output current in case of a transistor melt down") using PTC thermo fuses, if I remember.. Any recommendations on using them?

I have never seen a PTC thermo fuse. I do not know how accurate they are.

 

[audioguru2]

I can not find 2,5A slow blow fuse. Only 2A or 3,15A. Which is better to use?

Try a 2A fuse. If it burns out then try another 2A fuse. If it also burns out then use a 3.15A fuse.

 

[Big zee]

dear audioguru
I did the last update of the PS
but the ICs U1 and U2 gets hot and the voltage is 33 and I cant adjust it !
FYI the power supply is 28 volt and 3 amp

 

[Big zee]

what software did you use to draw the schematic ?
thx.

 

[audioguru2]

I did the last update of the PS
but the ICs U1 and U2 gets hot and the voltage is 33 and I cant adjust it !
FYI the power supply is 28 volt and 3 amp

Maybe you mean the transformer is 28VAC and 3A? Then without a load it produces a rectified and filtered about +39.6VDC.

U1 has a quiescent current of 3.5mA for a TLE2141, then its quiescent dissipation is 39.6V x 3.5mA= 139mW. Its output voltage is 11.2V and its output current is 5.6mA so it has (39.6V - 11.2V=) 28.4V across its output. Its output power dissipation is 28.4V x 5.6mA= 159mW. Then its total dissipation is 139mW + 159mW= 298mW which is far from its maximum allowed dissipation of 1000mW at room temperature ambient. It will be warm, not too hot.
U2 will be a little warmer but since yours is fighting the transistors then maybe it is destroyed.

The output cannot be controlled when the pins on the driver or output transistors are connected backwards.
These transistors are simply emitter-followers.   

 

[Big zee]

sorry its transformer and its 24v 3 amp
you are right there is problem  and i fixed it with the 2N3055
and replaced the TLE2141 but its stil gets very hot in 2 seconds and i cant adjust the voltage ! it 35 volts
is the U3 gets the U2 hot or its still the 3055  ???

 

[Big zee]

FYI
i used this PCB

 

[audioguru2]

Hello Big Zee,
Your image of the pcb is too small to read any of the part numbers. I cannot see the pins of the driver transistor.
The 2N3055 has a different and metal case than the transistors you are using. Are they TIP3055 by Motorola/Freescale?

Without a load your 24VAC transformer probably produces a rectified and filtered +35VDC.
With a +35VDC supply and no load current, U2 has a maximum output voltage of +33.8V.
The driver transistor is an emitter-follower with a maximum output of +33.1V.
The output transistors are also emitter-followers with a maximum output of +32.4V.
Then how can your output be +35V unless something is shorted to +35V??

If the driver and output transistors work properly then U2 has a low output current and will not get hot.
U3 simply reduces the input voltage to U2 (through D9) when the output current is higher than the setting of the current-setting pot.

I sketched a test for U2 by disconnecting the driver, output transistors and a few other things.

View attachment 41877

 

[Big zee]

no its 2n3055 not  TIP3055
the PCB already in here but i will attached it

 

[Big zee]

two more 

 

[Guber1]

Hi, i'm looking to build the latest circuit update but i have a doubt about the zener diode( D1) that is near to Q3, it seems to be a 10V 1W zener diode but i'm not sure. Thanks

 

[audioguru2]

Big Zee,
Your pcb shows that all the pins on the BD139 driver transistor are shorted together.

Guber,
The 10V zener diode D1 has 7mA for the LED and 3.5mA for opamp U3 in it so its max current is 10.5mA and it dissipates 10V x 10.5mA= 105mW. A 0.5W or 1W zener diode will be fine.
1N758A, 1N961B, 1N5240B, 1N6000B or many BZX European ones. 

View attachment 41883

 

[Guber1]

Big Zee,
Your pcb shows that all the pins on the BD139 driver transistor are shorted together.

Guber,
The 10V zener diode D1 has 7mA for the LED and 3.5mA for opamp U3 in it so its max current is 10.5mA and it dissipates 10V x 10.5mA= 105mW. A 0.5W or 1W zener diode will be fine.
1N758A, 1N961B, 1N5240B, 1N6000B or many BZX European ones. 

Perfect. Thanks

 

[Big zee]

yes
i fixed that with photoshop before print it
but i tried to connect the BD139 and the 2N3055 without the pcb
and the same thing and i disconnect all of them and the IC didnt get hot
and the 6th pin gives me 35 volts !

 

[audioguru2]

Big Zee,
Your camera is not clear enough for us to see any details.
I think since you had wiring problems with the output transistors then that caused U2 to be destroyed. Replace it.

Here is a sketch that shows how U2 should work. It has the driver and output transistors removed but the output voltages should be the same when they are connected.

View attachment 41887