Basically you run the control circuitry off e.g. a 12V little transformer, then rectify the mains to give you a DC rail to connect your SMPS transformer primary to. Adjust SMPS transformer pri:sec ratio to suit.
I believe further discussion on these forums is prohibited due to the lethal voltages involved. If you can't make instant sense of the above scheme then DO NOT ATTEMPT IT YOU WILL LIKELY DIE DUE TO VERY HIGH DC VOLTAGES
I believe further discussion on these forums is prohibited due to the lethal voltages involved. If you can't make instant sense of the above scheme then DO NOT ATTEMPT IT YOU WILL LIKELY DIE DUE TO VERY HIGH DC VOLTAGES
richie00boy said:Of course it works, that's how it's done commerciallyPFC is not required for such a small VA.
IMO for such a small VA I would just use a conventional linear supply, much safer and easier to get working and probably no bigger/heavier.
is it?i opened up an smps(12v,1amp),it was a telephone charger and had small transformers,tl494,and fast bridge.transformer didnt looked like standard 12-0-12.
cost savings will be great for smps.in my case,almost halved.+weight issues,linear power supply has ugly bulky xformer,very heavy +space savings.
can u suggest suitable core dimensions(torroid),will the same core as of car smps do?any special components that can be included?
any precautios or suggestions?
pinkmouse said:
Have you never seen the movie, Minority Report?
TOMMy,cops forsee,arrive b4 murder
pinkmouse,r u planin same system here
.moderators forsee postjacking,they come in n say"hey!u can't post today".
It may not be 'standard' 12-0-12 transformer, but remember it's not an audio device
The same core for your existing SMPS will be fine as it's the VA rating that counts, voltage is not a factor.
I was trying to say that for just 300VA, by the time you have added the control transformer and it's recitifying parts, the control circuitry, the mains rectifiying parts and the transformer, the whole thing won't be much smaller than a linear supply, as it's harder for the DIYer to make it so small. You also need to be well aware of creepage and clearance distances for the mains parts.
I say again that I would strongly advise you to keep to a simple and safer linear power supply. Do you realise that you will have near 400V DC present and DC is totally lethal at high voltage -- worse than AC.
The same core for your existing SMPS will be fine as it's the VA rating that counts, voltage is not a factor.
I was trying to say that for just 300VA, by the time you have added the control transformer and it's recitifying parts, the control circuitry, the mains rectifiying parts and the transformer, the whole thing won't be much smaller than a linear supply, as it's harder for the DIYer to make it so small. You also need to be well aware of creepage and clearance distances for the mains parts.
I say again that I would strongly advise you to keep to a simple and safer linear power supply. Do you realise that you will have near 400V DC present and DC is totally lethal at high voltage -- worse than AC.
ashok said:"........i suppose car smps also has high dc........"
If you don't know that after building and using a low voltage smps , you better not handle any high voltages. Someone might have to write your obituary. We sure wouldn't like that kind of a situation.
i know bout high voltages involved.i didnt 'see' them with mm,but i tested smps,it did 900w continous n was jus warm.
richie00boy said:
ok richie,got it.thanks for sound advise.
linear psu,i made two,very good,but very heavy and bulky.
u guys taking me a novice(i m new to diy),,but i wouldnt have made car smps and had such wonderful amps in the car had i backed off bec of dangers involved.
i have done experiments on heavy duty dc motors,induction motors
(all part of my studies),so heavy currents and adequate safety with their handling is not new to me.moreover,the dc power supply that i used to test car smps has 100amps output capability.
i really appreciate the sincere concerns of both of u.
Sagar
Hi Sagar,
The warnings are not to deter you from making a HV power supply. It is to prevent you from doing so till you REALLY are 'ready' to do such a thing. You can interpret that anyway , but we mean ' abudance of caution ' which I don't see in any of your posts. Overconfidence is the biggest killer !
High current has nothing to do with all this. Just lethal high voltages , in this case even more lethal , dc voltages. You need only a few milliamps to kill you . Depends on how you get the shock. Being paralysed is even worse than being killed ! So do be careful .
Handling electric motors is much easier and safer than handling high voltages on a circuit board !
Do not underestimate what electricity can do to you.
Keep DIY'ing ..............very carefully !
Cheers.
The warnings are not to deter you from making a HV power supply. It is to prevent you from doing so till you REALLY are 'ready' to do such a thing. You can interpret that anyway , but we mean ' abudance of caution ' which I don't see in any of your posts. Overconfidence is the biggest killer !
High current has nothing to do with all this. Just lethal high voltages , in this case even more lethal , dc voltages. You need only a few milliamps to kill you . Depends on how you get the shock. Being paralysed is even worse than being killed ! So do be careful .
Handling electric motors is much easier and safer than handling high voltages on a circuit board !
Do not underestimate what electricity can do to you.
Keep DIY'ing ..............very carefully !
Cheers.
so,for mains voltage,should i start with low power?
i want an smps,i envisage a small class d amp(200 to 300w),powered by an smps power supply.Imagine the light weight and space savings of smps and class d amp.no bulky and costlier-than-components heatsinks.no heavy transformers.all in a small and smart little casing.IMAGINE!the little devil than can pump out huge power
could u guys be kind enough to tell me the requisite safety precautions that need to be taken?any special components to be used on primary side,any protection circuits that should be included?
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.1 amp is SUFFICIENT to kill.
i want an smps,i envisage a small class d amp(200 to 300w),powered by an smps power supply.Imagine the light weight and space savings of smps and class d amp.no bulky and costlier-than-components heatsinks.no heavy transformers.all in a small and smart little casing.IMAGINE!the little devil than can pump out huge power
could u guys be kind enough to tell me the requisite safety precautions that need to be taken?any special components to be used on primary side,any protection circuits that should be included?
----------------------------------------------------
.1 amp is SUFFICIENT to kill.
NO NO NO please read what we are saying. The power is irrelevant, the issue is the lethally high DC voltage that will be present for ANY mains powered SMPS no matter how low power.
Apart from the physical safety issues there will be creepage and clearance issues which you will have never encountered before.
I appreciate your enthusiasm but this is not a project that you are ready for yet.
Apart from the physical safety issues there will be creepage and clearance issues which you will have never encountered before.
I appreciate your enthusiasm but this is not a project that you are ready for yet.
A good overview on safety aspects:
http://focus.ti.com/lit/ml/slup227/slup227.pdf
Then there are safety issues during prototyping and measuring performance of prototype. First, dont even think about it without isolating transformer. Second, keep one of your hands always in pocket. Wear safety glasses.
http://focus.ti.com/lit/ml/slup227/slup227.pdf
Then there are safety issues during prototyping and measuring performance of prototype. First, dont even think about it without isolating transformer. Second, keep one of your hands always in pocket. Wear safety glasses.
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