boylesg
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But probably scheme is wrong collected and simply does not work. On photographies it is difficult to see details.12V in and I get between 11V and 12V out
Thanks Deepone. What should IPK ideally be then?Hi, Boylesg.
>IPK (mA): 1553.097345 < - is too big chip will be powerfully warmed and will not provide reliable work.
.
See that is the problem. There is not much to get wrong with this circuit and I have been over it in conjunction with the shematic a few times and can't see any mistakes. So there must be something else wrong.But probably scheme is wrong collected and simply does not work. On photographies it is difficult to see details.
I think no more than 1A.What should IPK ideally be then
With increase the frequency requirements to arrangement of the design are tightened.Are you suggesting that I am trying to run the chip at a frequency that is too high to be reliable?
Typical frequency is 30Khz. Change Ct = 1n. (At least try to see result)
DeepOne is right. The problem of your board is that it was done not for high speed process. It means that your board has a long wires (ground path, signal path and so one) and has a large parasitic inductions, that affect on frequency.
From my experience I need notice that MC34063 doesn't work good on high frequency. In my applications I used 30-50Khz frequency not higher.
Why regulate a high voltage then drop it down again?
Wire a potentiometer to pin 5 and it will let you adjust the voltage out of the MC34063.
Brian.
Using a second regulator will seriously reduce efficiency because you have to generate too much voltage before the LM317 and lose it as heat in both regulators to drop it down again. The improvement in ripple, if any, would be nefligible and unless you were very careful with wiring it could even make it worse. Your best bet is to add an additional filter if necessary and control the voltage at source in the MC34063. Remember that at the relatively high ripple rate you don't need such bulky filter components than if it were a 50Hz/60Hz non-switching regulator. A simple LC circuit would suffice.
Brian.
You may experiment with this calculator for MC34063 here for different settings:
**broken link removed**
Also this:
http://www.nomad.ee/micros/mc34063a/
Don't give up!
If it helps, I'm in my late 50's and in my whole life I've never had any tuition or training in electronics and only had one day training in software. The morning was a crash course in 'C' because I needed it for the afternoon crash course on Unix! Needless to say, by the end of the day my head was about ot explode. I'm just an amateur experimenter like you but from what I taught myself I've been head-hunted to do work for several multi-national electronic giants and worked on high level projects around the World (and further away).
I would say you have shown a healthy curiosity over how things work but perhaps bitten off a bit too much to digest in a short time. Switch mode regulators can be intimidating and frustrating when they fail to do what you expect but don't give up, just look very closely to see what's gone wrong. You learn more by finding out why things have failed than by reading the manufacturers hype about how good their products are. Look at it this way - if someone had made the perfect SMPS IC, why are there hundreds of different types on the market. They all have problems of some sort and part of the 'fun' is finding ways to work around them and design defensively to avoid the pitfalls in the future.
With experience, your frustraton level will diminish and you will feel more confident about using more advanced components and applications. You will eventually stop hating data sheets and start hating the people who change their design requirements just after you sent thier PCB to the fabricator! Those of us who have been around a while will know exactly what I mean.
Brian.
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