0-30V Stabilized Power Supply

[Comwiz999]

Hey guys

I would like to build this circuit and I am looking for the best working solution..There are so many revisions I am not sure which is best.

Can anybody please advise me on  this?
Thanks

 

[audioguru2]

I would like to build this circuit and I am looking for the best working solution..There are so many revisions I am not sure which is best.

Can anybody please advise me on  this?

The latest revision (schematic Rev2 and parts list Rev3) is reliable, inexpensive and works well. View attachment 41598

View attachment 41599

 

[Comwiz999]

I seem to be having a problem sourcing the parts. The closest the biggest supplier in the country can only offer is a 2x15VAC transformer. Can I use this? Otherwise, a 24VAC transformer is availible. Is there any good options for this voltage?

 

[audioguru2]

I seem to be having a problem sourcing the parts. The closest the biggest supplier in the country can only offer is a 2x15VAC transformer. Can I use this? Otherwise, a 24VAC transformer is availible. Is there any good options for this voltage?

2x15VAC is fine (30VAC) if it is rated for 126VA or more or 4.2A AC or more.
With a 24VAC/102VA transformer the max output from the project is about + 25VDC at 3A.

 

[fly3rman]

@ audioguru

Ive calculated the working point on my circuit (42v plus, -1.6 volt minus) to a voltage divider of 10k ohm and 440 ohm. Already did a dirty testing with 10k and 470 ohm, its better, but still problematic. Still the d10 isnt in so far.
I will do more testing with a potentiometer, but there is a flaw in the design with the voltage divider i think.
If plus voltage is kept up and minus voltage drops, the q1 can work. But there will be a point, where plus voltage is also very low, so the needed base voltage cant be kept up and it will be conduct again. Still, this can kill an LED.


The approach must be different, the complete ouput must be OFF as along as plus voltage is under 42V and minus voltage is over -1.3V.
I will try followin approach (maybe in addition): a closing mechanic relais:
http://www.produktinfo.conrad.com/datenblaetter/500000-524999/503605-da-01-en-RELAIS_ZETTLER_AZ762_1A_48DE.pdf
"Must operate DC" for 60 DC Coil is 42V. The difference between our plus and minus lanes is ~43.5V. Connected to this and if one lane drop voltage (off behaviour), the relais is open and output is OFF.

 

[audioguru2]

The "must operate" voltage of a relay is the maximum coil voltage to activate it. Its maximum must operate voltage is 42V and its minimum might be only 30V or less.

Its "dropout" voltage is a minimum of 10% of its nominal 60V rating which is only 6V.
So it is useless to detect when the supply voltage drops.

A comparator is a device that accurately detects when a voltage has dropped to a certain amount.

 

[Tompa1]

hello everyone ( specially audioguru "")

I'm from Croatia, and i can't anywhere buy tle2141 or mc34071, so i will buy it on ebay. Now, i want to know is this right one tle2141cp (or is it possible to buy some substitue?) ( http://www.ebay.com/itm/Single-Operational-Amplifier-TLE2141CP-/330629861183?pt=LH_DefaultDomain_2&hash=item4cfb134f3f#ht_1331wt_1110 )

thank you in advance

PS. Sry for my english. :/

 

[audioguru2]

hello everyone ( specially audioguru "")

I'm from Croatia, and i can't anywhere buy tle2141 or mc34071, so i will buy it on ebay. Now, i want to know is this right one tle2141cp (or is it possible to buy some substitue?) ( http://www.ebay.com/itm/Single-Operational-Amplifier-TLE2141CP-/330629861183?pt=LH_DefaultDomain_2&hash=item4cfb134f3f#ht_1331wt_1110 )

Yes that is the correct IC. The E-Bay seller is in my country and sells it at almost double its normal cost here. I don't know how much the shipping will cost to your far away country.

 

[optimistic]

I found some interestin solution about original sheme here http://www.electronics-lab.com/projects/power/001/index.html

Received the following email from Ivan on 02/2010:

Ok. I bulid your project about a day ago. Mounted all the parts on the pcb and then concluded that there is some serious problems in this schematics. First, 2N3055 will overheat, so you have to connect two of them in parallel with emitter resistors 0.1ohm/5w. Second, maximal voltage between '+' and '-' of TL081 is 36VDC.If you connect them as it is shown in this circuit diagram that voltage will be about 45VDC, so they will burn down immediately. To fix this problem you have to reconnect all pins number 7 of U1, U2 and U3, emitter of Q3 and 'upper' end of R19 to out of an 7809 with 18V zener diode between 'common' pin and '-' of 3300uF cap, and input of 7809 connect to '+' of the same cap. Now, on pin number 7 and mentioned parts you'll have 27VDC, and total voltage will be 32.6VDC. Third, instead of using 3300uF, use 4700 or 6800uF/63VDC to reduce the ripple on higher currents (2-3A). The rest of the circuit is perfect. I like it cause it is so inexpensive and easy to make with those simple reconstructions i mentioned.

What think about this???

 

[audioguru2]

I found some interestin solution about original sheme here http://www.electronics-lab.com/projects/power/001/index.html



What think about this???

With 27V on the output opamp then the max output of the project will be only about 21V, not 30V.
You would have the same 21V max output if you used a 21V transformer. Then only a single 2N3055 output transistor is needed and the driver transistor will be cooler.

Why not use the newer 44V opamps and a -1.3V negative supply instead so that the output can be 30V?

 

[Captdaverobinson]

Hi, just trying to source a transformer for this.

RS do a 2x15V 4A essentials toroidal transformer.  I realise that this only rates at 120VA rather than the 126VA recommended.  Is it possible to use this? If so what effect will the missing .2A have on the output?

 

[audioguru2]

A 120VA transformer is slightly too small. Then when the project is supplying 3A continuously the transformer will be slightly warmer than its max allowed temperature.
Inside a box it might get too hot.

 

[optimistic]

With 27V on the output opamp then the max output of the project will be only about 21V, not 30V.
You would have the same 21V max output if you used a 21V transformer. Then only a single 2N3055 output transistor is needed and the driver transistor will be cooler.

Why not use the newer 44V opamps and a -1.3V negative supply instead so that the output can be 30V?

I'am from Bulgaria and i can't find the newer opamps. I need to find some other solution.....

 

[audioguru2]

I'am from Bulgaria and i can't find the newer opamps. I need to find some other solution.....

Look at www.farnell.com to see that they supply modern electronic parts in your country.

 

[Captdaverobinson]

A 120VA transformer is slightly too small. Then when the project is supplying 3A continuously the transformer will be slightly warmer than its max allowed temperature.
Inside a box it might get too hot.

Many thanks.  As I do not anticipate using the supply at 3A a lot, nor for long periods I think I will go for this option and just be sensible about suitable cooling.

You do a great job on here, I am sure that many other appreciate your advice as well.

All the best

 

[aop9020]

Hello.
I'm new here.. Hello

Do I really have to read through all the 85 pages to find out where I can get an updated BOM, schematic, and eagle drawings?

Thanks.

Andreas

 

[audioguru2]

Hello.
I'm new here.. Hello

Do I really have to read through all the 85 pages to find out where I can get an updated BOM, schematic, and eagle drawings?

Thanks.

Andreas

Hi Andreas.
It is too bad that the power supply kit posted in the original project was very poorly designed.
We have made a few modifications over the years to fix it and I have posted the latest parts list and schematic millions of times.
Here they are again:View attachment 41607

View attachment 41608

 

[benny8902]

A 120VA transformer is slightly too small. Then when the project is supplying 3A continuously the transformer will be slightly warmer than its max allowed temperature.
Inside a box it might get too hot.

What if the transformer is bigger? Like 150VA. would that be a problem?

 

[audioguru2]

A 150VA transformer will be fine but is more expensive and is heavier.

 

[zulcao]

Recently I got an 1000va by 24v, will work ?