Electronics > Beginners
RPS with from 0-30V and Current variable up to 3 A design Circuit Please....
Kleinstein:
The kind of linear cross over between separate transformer taps is a good option at intermediate power.
It can be done even simpler, especially if the floating regulator circuit is used and only 2 taps.
It may not be the most economic way, thought not that bad (mainly more filter caps). On the positive side it's simple and about half the worst case heat compared to the single tap way. So it's about as good as using relays for 3 transformer taps as one can go closer to the edge.
It depends wether the reduced (about half) heat sink can make up for about 1.5 times the filter caps.
There is a lab supply project using this system, though with MOSFETs:
https://www.eevblog.com/forum/projects/diy-bench-power-supply-psl-3604/
This supply could be a good option - at least a good point to learn from. For simplification one could use classical rectifier if a little more loss is acceptable.
rstofer:
--- Quote from: Kleinstein on January 12, 2019, 10:56:06 am ---
There is a lab supply project using this system, though with MOSFETs:
https://www.eevblog.com/forum/projects/diy-bench-power-supply-psl-3604/
This supply could be a good option - at least a good point to learn from. For simplification one could use classical rectifier if a little more loss is acceptable.
--- End quote ---
It might be a little over the top for a newcomer.
If we had a sticky thread for PSs, this should certainly be a candidate.
techguru:
--- Quote from: not1xor1 on January 09, 2019, 07:04:22 pm ---
--- Quote from: Zero999 on January 09, 2019, 09:20:40 am ---
--- Quote from: not1xor1 on January 09, 2019, 07:48:42 am ---I do not think there is a lack of such schematic diagrams neither that it would be more difficult to design than e.g. a 0-15V 1A PSU.
4 large heatsinks and 8 TO3 BJTs can work for more than 120W of wasted power even without the help of fans.
It just does make little sense and would be more expensive than using a suitable multi-tap transformer based PSU.
--- End quote ---
Go on, post your design. . .
He's right. It's not so much the current, but the voltage which is the problem. At 15V, an ordinary op-amp can be run from the unfiltered rectifier voltage. With 30V something more elaborate is required. The absolute maximum voltage rating of most standard op-amps is under 44V, which would be an AC voltage of just over 30V on the transformer secondary. A lower voltage transformer could be used, but that doesn't leave much headroom for voltage ripple.
--- End quote ---
You must be kidding... nothing easier than that. ;D
I made this from a quick copy & paste from other .asc files so there are likely some problems although it works flawlessly in the simulator.
BTW to play with it you need TL431 and BD140 models.
--- End quote ---
Sir,
How to analyse this schematic. Where to start my analysis to understand the circuit?
What is the book to learn to develop Understanding skill for Discrete or Integrated circuit?
BravoV:
--- Quote from: rstofer on January 11, 2019, 08:26:49 pm ---
--- Quote from: BravoV on January 11, 2019, 10:07:45 am ---With all excellent replies, advises, tips and even circuit, I guess the OP will not create, yet another new thread nagging for a new 723 based 30V 3A psu again, as this is the 5th one or 6th already ? :-//
Its just sad to see all goodwills and helps going to be wasted again if this happened.
--- End quote ---
But maybe some of the responders, like myself, are learning something about the problems created by the "specs". Yes, I have spent some time wandering around, bouncing off of other schematics and different approaches to the problem and, as a result, I have a new appreciation for the problem.
If there was a simple design that had a decent bill of material, it would be a 'sticky' and served up as the universal answer to a DIY power supply. Alas, it isn't simple!
As I see it, there are two choices: First, come up with a more realistic spec or, second, plan on finding a transformer with secondary taps. I don't know how hard it would be to wind a custom toroid. Maybe buy one, unwind the secondary and then rewind it with taps.
There are a lot of commercial supplies that advertise to meet the spec and they tend to be in the $50-$60 range. I don't know that they actually meet the spec but I would tend to just buy one rather than try to build one.
--- End quote ---
I am a electronics hobbyist, totally understand your point above, nothing against it what so ever.
Its just you don't realize what the OP's have been done here, hint, just read from the bottom the list of threads created since the beginning, no need to read the thread's content, just the title ...
The OP's created threads list -> https://www.eevblog.com/forum/profile/?area=showposts;sa=topics;u=154644
Actually the current nick is his second, as he re-registered here to get a fresh new nick, as before, his old nick where he felt no one could give him satisfaction, btw, he admitted it already. :palm:
Again, just read the thread's title to get a clue ...
Previous abandoned nick threads list , started from mid 2017 :palm:-> https://www.eevblog.com/forum/profile/?area=showposts;sa=topics;u=138516
The point, he will nag until someone come with a full schematic that uses 723 with 30V 3A capable, and also must utilizes components that are available in his drawer, if not, he will make another thread again, or re-register as new user when most "helpful & friendly" people exhausted on his nick.
He does not have technical problem at all, nor language barrier, he has really bad netiquette and bad attitude.
techguru:
--- Quote from: BravoV on January 12, 2019, 05:45:25 pm ---
--- Quote from: rstofer on January 11, 2019, 08:26:49 pm ---
--- Quote from: BravoV on January 11, 2019, 10:07:45 am ---With all excellent replies, advises, tips and even circuit, I guess the OP will not create, yet another new thread nagging for a new 723 based 30V 3A psu again, as this is the 5th one or 6th already ? :-//
Its just sad to see all goodwills and helps going to be wasted again if this happened.
--- End quote ---
But maybe some of the responders, like myself, are learning something about the problems created by the "specs". Yes, I have spent some time wandering around, bouncing off of other schematics and different approaches to the problem and, as a result, I have a new appreciation for the problem.
If there was a simple design that had a decent bill of material, it would be a 'sticky' and served up as the universal answer to a DIY power supply. Alas, it isn't simple!
As I see it, there are two choices: First, come up with a more realistic spec or, second, plan on finding a transformer with secondary taps. I don't know how hard it would be to wind a custom toroid. Maybe buy one, unwind the secondary and then rewind it with taps.
There are a lot of commercial supplies that advertise to meet the spec and they tend to be in the $50-$60 range. I don't know that they actually meet the spec but I would tend to just buy one rather than try to build one.
--- End quote ---
I am a electronics hobbyist, totally understand your point above, nothing against it what so ever.
Its just you don't realize what the OP's have been done here, hint, just read from the bottom the list of threads created since the beginning, no need to read the thread's content, just the title ...
The OP's created threads list -> https://www.eevblog.com/forum/profile/?area=showposts;sa=topics;u=154644
Actually the current nick is his second, as he re-registered here to get a fresh new nick, as before, his old nick where he felt no one could give him satisfaction, btw, he admitted it already. :palm:
Again, just read the thread's title to get a clue ...
Previous abandoned nick threads list , started from mid 2017 :palm:-> https://www.eevblog.com/forum/profile/?area=showposts;sa=topics;u=138516
The point, he will nag until someone come with a full schematic that uses 723 with 30V 3A capable, and also must utilizes components that are available in his drawer, if not, he will make another thread again, or re-register as new user when most "helpful & friendly" people exhausted on his nick.
He does not have technical problem at all, nor language barrier, he has really bad netiquette and bad attitude.
--- End quote ---
Mr Bravo,
I totally deny you. may be my specification may be to high for a beginner and Now i feel There is no need to built a circuit which can deliver 100W of power. Neither i could go for LT3080 which could control both voltage and Control regulation with dissipation of Nearly 30W. This is what i would understand from this forum.I cannot analyse big circuit. I donot know where to start my analysis.
Here i could not get the component which we have discussed in this thread. What ever is available here i could use it.I could not order from online website because i am student of electronic engineering. my economy wont allow me.
A simple LM723 cost ten rupee which is affordable my me. So i was searching for circuit with LM723. This is the reason for those those thread.
I respect every one in this forum, Sorry If i hurted you all. Thank you all .
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