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0-30V Stabilized Power Supply


redwire
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You said you used the SIM program called Protues, not Proteus.
Most of us use the newer SIM program called LTspice IV.


OK, so the problem was about an "e" and an "u" !!
I just downloaded the LTspice IV, seems to be a very simple software and to have a poor component library!
In my Proteus project, I changed the generator (AC) phase delay to 60 degrees,

and unbelievably when I run the project, the output voltage was 29.249 VDC which is what I wanted to have, but when the phase delay is zero, the output is 15 VDC
can you explain why these things happen?!
thanks a lot
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I just downloaded the LTspice IV, seems to be a very simple software and to have a poor component library!

There is a Yahoo users group where they make models for any part

In my Proteus project, I changed the generator (AC) phase delay to 60 degrees, and unbelievably when I run the project, the output voltage was 29.249 VDC which is what I wanted to have, but when the phase delay is zero, the output is 15 VDC
can you explain why these things happen?!

I don't know why you are simulating this simple power supply, I don't know what you havew a "phase delay" and I don't know why its voltage is wrong. Simply build it and measure it.
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I don't know why you are simulating this simple power supply, I don't know what you havew a "phase delay" and I don't know why its voltage is wrong. Simply build it and measure it.


I simulated this power supply so that I can see if there is any problem, before creating this. I'm a little pernickety in my works  ;D .
OK , so I'll create it!! I'm so thankful for your support, like you!
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Does your SIM program see parts smoking or failing that are overloaded?
Does it know about the electrolytic absorption in the electrolytic output capacitor that causes the output voltage to rise when there is no load?
Does it know about the input offset voltages of opamps?
Does it know that each part has a tolerance?
I think it knows about none of these problems.

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hey guys ive posted here a couple times this time  i think i got it right.  need help on my progect ive built the newest version of the supply and for the most part it works. my problem is the output of u1 ( this is the picmaster version so follow his print) ive got 34v at the rails but my output at u1 doesnt drop below 17 volts and it goes up to 34 volts  i thought this was a lower voltage output not maxed at 34v to drive the transisters. also i noticed when looking at the scope as im increasing or decreasing p2 that pin 2 and pin 3 will follow each other from ov up to about 5 to 6 volts then pin 3 will rise on its own (as i increase pot) and output will then start to rise from 16v to 34v switched chips so i know its good. hey guys i know you love this stuff please help ive got a couple months on this progect and would like to see it work. also this is all with 2 series 56k resister conn at output.

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need help on my progect ive built the newest version of the supply and for the most part it works. my problem is the output of u1 ( this is the picmaster version so follow his print)

I think PicMaster changed all the parts designation numbers so we don't know which opamp is U1.
Please post the schematic you used.

ive got 34v at the rails but my output at u1 doesnt drop below 17 volts and it goes up to 34 volts  i thought this was a lower voltage output not maxed at 34v to drive the transisters. also i noticed when looking at the scope as im increasing or decreasing p2 that pin 2 and pin 3 will follow each other from ov up to about 5 to 6 volts then pin 3 will rise on its own (as i increase pot) and output will then start to rise from 16v to 34v switched chips so i know its good. this is all with 2 series 56k resister conn at output.

If the emitter and collector of the driver or output transistor are wired backwards then the emitter-base becomes a 7V zener diode preventing the output of the output opamp from going less than about +27V.
Only one 56k resistor is used for negative feedback, not two of them.
Which opamps did you use?
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yes of course my picmaster version U1 is your march 11 rev2 U2. the one emmiting to the driver base emitter which im using tip3055 to-220 also i using the mc34071 chips which none of them are really even getting warm. im using 2 56k resisters at the output terminal to add a 112k load. question: the negative feedback coming through r12 and c6 (your version) this signal is stable is it not or does it drop and raise as i adjust p1(your version) on my board the output of u2 goes as high as 34v but only drops as low as 16volts and these voltages seem high driving tip3055 isnt the base emitter voltage of tip3055  only 7 volts. my output never drops  below 16v my inverting and noniverting pins 2-3 follow each other up from 0v to 7v then only the inverting pin 2 continues to rise to 11.15 volts.  why isnt the noninverting pin 3 continuing to rise due to its connection to p1 instead my negitive feedback cirtcuit through r12 and 6c voltage rises to 11.15volts is this due to the 3x gain. which brings me back to why doesnt my voltage drop below 16volts with the pot all the way down. i check my pinouts thought they looked good cant see them being a problem do you still think i have one switched around ill send pickmaster pdf its pretty thurow i used his eagle design printed it with laser and irond it and eched it the traces wernt perfect they all look good now

EL_power_supply.pdf

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I've made 2 PicMaster's version PCBs. They are working well. Since now I had a transformer only for one PCB, so I ordered a new transformer, which can supply both power supplies. The ordered transformer should be with 2 secondaries without common on 31 without load (so approximately 29-30V with load). Now I got it, but the company did a mistake as I see. The transformer have 33,5V without load, I think they did it on 31V with load. I tried one PCB with it. The input voltage is between 32-33,5V ( tried it with a DC motor on 13V 1,5A). There weren't any problems, but should I make some changes on the schematic to use this transformer. May be if I turn on both PCBs the input voltage will drop more, but still it will be over 30V I think. What to do?

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the driver base emitter which im using tip3055

The driver transistor is supposed to be a high frequency BD139, not a low frequency TIP3055 for good transient response.

question: the negative feedback coming through r12 and c6 (your version) this signal is stable is it not or does it drop and raise as i adjust p1(your version)

In an opamp circuit that has negative feedback and no output clipping, both inputs have the same voltage.

isnt the base emitter voltage of tip3055  only 7 volts?

No, it is 0.6V to 1.5V depending on the current.

my output never drops  below 16v .....  why doesnt my voltage drop below 16volts with the pot all the way down?

I think beause you have the pins on a transistor or all of them connected backwards.
PicMaster probably used a BD139 driver transistor. If you used a TIP3055 then its pins are backwards.

post-1706-1427914438788_thumb.png

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I ordered a new transformer, ..... it has 33,5V without load.

Simple arithmatic shows that the unregulated voltage will be 46V which is too high since the absolute max voltage for the TLE2141 or MC34071 opamps is 44V.
Reduce the 46V to 41.3V with a 4.7V zener diode in series with the positive supply pin of my U1 and U2.
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How much Watts should be the 4V7 zener?

Power is measaured in Watts. Power is volts multiplied by amps. The volts for a 4.7V zener diode is 4.7V and some of the current can be found on the datasheet for the opamps which is 4.5mA max. Each opamp has a load current of 5.5mA so the total current in each zener diode is 10mA.
Then the power in the zener diode is only 0.047W which is nothing so a 1/4W zener diode is fine. Use a zener diode tested at 5mA or 10mA like a 1N5992B, BZX55C4V7, BZX83C4V7 or BZX79C4V7.
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audioguru you are unbelievable you know i had the bd139 on the board and changed them out with a tip3055 cause i could only get the bd139 into126 package thinking the plastic case would needa larger heatsink i have tip3055s as output transisters but these are much larger than the tip3055 i got at radioshack and replaced the bd139s with well iguess i switch them back cause you are correct the pins are backwards hope i dont fry them with all this soldering and desoldering. cant believe i missed this. audioguru your incredible thanks for getting me straight ill let you know how it works 

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On the first of the PCBs I put 2 4,7V zeners, on the second i put 4,7V on U2 and 5,1V on U1 (i hadn't one more 4,7V). When only one of them is turned on (the one with the 2 4,7V) has 30,4V ouput. When I turn and the second one on, maximum output is 29,7V. The PCB with the 5,1V zener has ~ 27V when both are turned on. So I suggest to put less than 4,7V zeners (4,3V may be) ?

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Morpheous,
If your transformer produces an unregulated 46VDC without a load, then it must be producing only 41VDC with a load which is horrible voltage regulation.
Or maybe the value of the main filter capacitor is too low.

Maybe your transistors were damaged when you had them connected backwards.

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i turned the driver transisters around and the powersupply worked great right up until i hooked up my 18v dewalt drill test motor i may have over amped the circuit i dont know i didnt have ampmeter tied in but now i get 34 volts through the output nothing less on picmasters verion theres a seperate board for the driver transister and output transisters. ive disconected them and still get 34v0lts at pin 6. in audiogurus version c9,c6,r12,r11are all that are connected to pin 6 i dont see how any of these could have failed and output 34volts to pin 6 i have switched chips same thing

also i do get 0 t0 11 volts at inveting pin 3 just noninverting pin 2 stays at 0 volts

also i do get 0 t0 11 volts at[glow=red,2,300] noninveting [/glow]pin 3 just [glow=red,2,300]inverting pin [/glow]2 stays at 0 volts sorry had these backwards

Posts merged by moderator. Please use the modify button (it looks like this modify.gif) in future rather than making multiple posts.

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