But the caps i am a little confused about - in the guide it says a general rule is 470 uF per 0.1 ampere - the transformer will provide 2x167mA - Meaning something lik 2x470uF on both sides, so around 1000 uF caps - and here i need 1 electrolytic and 1 cheramic for pos and neg side before and after the 7812/7912 - correct? To sum it up:
The caps need to be able to withstand the rectified voltage, no need for low esr ones. So use a 25V one: RAD 105 1.000/25 but i would personally take a 2200u one . For the non polarity ones use X7R-5 100N or Z5U-2,5 100N
The caps need to be able to withstand the rectified voltage, no need for low esr ones. So use a 25V one: RAD 105 1.000/25 but i would personally take a 2200u one . For the non polarity ones use X7R-5 100N or Z5U-2,5 100N
Thank you Shuriken
Trying to get my head around these electronics one step at a time
It definitely depends on what you are planning to drive with this PSU. MFOS’ design is not a bad choice, especially if you want to go for a small footprint and don’t need a lot of power. However, it’s a bit like sucking every last mV out of the wall wart to produce +/-12V, hence the huge cap bank and the feedback diods.
Also make sure you have an old school transformer in your wall wart and not a switched PSU, or directly go for a transformer. This design is suitable for basic functionalities without critical VCOs or circuits which need an absolute rock solid voltage source or a lot of power.
If you can afford the cost, space and weight, I would go for a +/-15V center tapped transformer, as this will leave you with enough head room for mains noise, drops and ripple. You can also go more for the 2200uF-3300uF range than the 9900uF tank bank, which cuts cost on the other side. However, that’s the opinion of an analog synth builder who needs a stable +/-12V source with about 1.2A.
You’re talking about 167mA transformers. One thing to consider is, that the AOUT_NG alone sucks about 40mA without the core, any other module, display or subsequent circuits attached. So keep power consumption in mind.
Disagree 100%, an “old school” linear supply will be 10x bigger, 5x more expensive, and will get much hotter than a modern decent switching one which will also be 5x more efficient, just search the forums and see how many people here are using Meanwell PSUs without any issues. There is a reason that no one uses big linear supplies any more. For a $40 Meanwell you get a 5A 5V rail with +/-12V. How much would just a linear transformer cost to do 5A? Buchla Music Easels use SMPS for a reason.
Disagree 100%, an “old school” linear supply will be 10x bigger, 5x more expensive, and will get much hotter than a modern decent switching one which will also be 5x more efficient, just search the forums and see how many people here are using Meanwell PSUs without any issues. There is a reason that no one uses big linear supplies any more. For a $40 Meanwell you get a 5A 5V rail with +/-12V. How much would just a linear transformer cost to do 5A? Buchla Music Easels use SMPS for a reason.
Sorry, I think this is a misunderstanding. I didn’t want to say that a switching supply won’t be a good choice at all. What I mean is, that a switching wall wart will likely cause troubles with the MFOS design, as the caps as well as the backward diodes are specifically designed for old school transformers with a 50Hz cycle. I just mentioned this, as nowadays it is not always clear what you get if you have a wall wart. However, it is very unlikely that there are many switching wall warts on the market which produce AC.
But I think this input about using a switching PSU instead of a conventional one has definitely to be considered in the first hand.
Didn’t see all the replys on this topic - i was planning to build this just for the AOUT, but maybe i could switch out the transformer to get more current and tap out 5v DC for the core also? Only having one power supply would be nice :)
I ordered all the stuff, so now i am just going for this, but next time i’ll check out the Meanwell.
