Or, am I better off with something like this:
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Would the 24VA 0-12V be able to squeeze out 1A?
Or else, I'd just go with an LM317 (Motorola) followed by MC7812 (On). From datasheet, the MC7812 has better noise spec (120uV vs 360uV @12V), but worse ripple rejection.
Either way, I am returning that small transformer.
What's the part of "it won't work" you don't understand?
a) as Elvee said, you don't have enough raw voltage to get 12V regulated under that load. No way.
And once the linear regulator saturates, you won't have microvolts of ripple but big ugly *Volts*.
b) And if you cascade 2 regulators, *both* will be saturated or worse (maybe even unable to pass current), you'll have full raw ripple at the outout and even worse .... you won't even have 12V !!!!!!!!!!!!!!!!!
c) the regulator you posted can't pass 1A .... or 100mA ... best case it can supply some 20mA regulated.
Now, if you parallel 50 of them , yes, you can supply 1000 mA.
What's the part of "it won't work" you don't understand?
I don't understand the "it" part. 🙂
a) as Elvee said, you don't have enough raw voltage to get 12V regulated under that load. No way.
And once the linear regulator saturates, you won't have microvolts of ripple but big ugly *Volts*.
He said that with "standard" regulator. I assume the LM317 and the like. I have no idea if the that zener circuit is "standard". Which is the reason I am asking. I am sorry if that is obvious to you, it is not to me. 🙂
b) And if you cascade 2 regulators, *both* will be saturated or worse (maybe even unable to pass current), you'll have full raw ripple at the outout and even worse .... you won't even have 12V !!!!!!!!!!!!!!!!!
I never said I am going to do that with a 12V transformer.
c) the regulator you posted can't pass 1A .... or 100mA ... best case it can supply some 20mA regulated.
Now, if you parallel 50 of them , yes, you can supply 1000 mA.
That is what I want to know. Thank you. 🙂
There is no single solution. That broad range of capacitance could, on its own, be considered correct.
Werner Ogiers' voltage regulator article, and a predecessor, Reduce Noise in Voltage Regulators by Erroll Dietz (available online or as an appendix in Bob Pease's Troubleshooting Analog Circuits), are better than the datasheets at showing just how much of a balancing act is involved. A forum search for regulator output noise and output impedance will no doubt turn up more discussion on the topic.
I wasn't able to reproduce Werner's results in simulation for the simple zener - emitter follower regulator. Oh well, try again later.
I have generally found that 317's are quieter than 78xx, but that is anecdotal, and there could be significant variations, both part to part and manufacturer to manufacturer.
Yes, there is a big difference in noise performance among the different manufacturers of the LM78XX and LM79XX series. Also, the best noise for a positive regulator comes from a different manufacturer than the one that has best noise performance for the negative regulators.
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So, I already have 2x2200uF and 1x10000uF electrolytic capacitor.
Am I better of putting the 2x2200uF at C3 and the large 10000uF at C6 instead? Or the other way round? If the 2x2200uF is at C3 I can put a small resistor in between as Simon suggested.
If you do this, don't forget the protection diodes, as outlined in the data sheet.
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