Hello all.
Im curious if it would be safe enough to use the 18V 1000mA AC PSU as is, without rewinding , as i have one spare. I would look at the nava schematics to figure it out myself, but i can't find it yet (maybe i missed that somewhere?).
18VAC PSU ?
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e-licktronic Site Admin - Posts 519
- Joined: Feb 16th, '11, 13:36
Nava Schematic is in the shop in the download section on Nava kit page.redstorm wrote:. I would look at the nava schematics to figure it out myself, but i can't find it yet (maybe i missed that somewhere?).
Best regards,
e-licktronic
Best regards,
e-licktronic
e-licktronic
Thanks for the schematics!
At first i noticed 16v capacitors there, but that is not really an issue as capacitors in bom is better.
Then i take a look at the IC datasheets, starting with M5218L OPamps.. And it seems that "absolute maximum" voltage is +/-18v for them, which is already uncomfortable when using mains transformer without stabilization (in the event of voltage bumps or so).
So to answer myself, that may be possible, but is not safe.
Better to use less than +/-18v.
At first i noticed 16v capacitors there, but that is not really an issue as capacitors in bom is better.
Then i take a look at the IC datasheets, starting with M5218L OPamps.. And it seems that "absolute maximum" voltage is +/-18v for them, which is already uncomfortable when using mains transformer without stabilization (in the event of voltage bumps or so).
So to answer myself, that may be possible, but is not safe.
Better to use less than +/-18v.
If you are talking about an external 18VAC wallwart, the answer is yes it's safe to use. I use an 18VAC wallwart with my Yocto without problems.
The 7815 and 7915 voltage regulators in the PSU section of the Nava are rated to have a maximum input voltage of 35v and the 2200uf smoothing caps are also rated at 35v so an 18VAC input won't be a problem. The only thing to be aware of is that the regulators will get a little hotter but nothing that a properly fitted heat sink can't deal with.
The 7815 and 7915 voltage regulators in the PSU section of the Nava are rated to have a maximum input voltage of 35v and the 2200uf smoothing caps are also rated at 35v so an 18VAC input won't be a problem. The only thing to be aware of is that the regulators will get a little hotter but nothing that a properly fitted heat sink can't deal with.
Oh, well.. i completely forget about 7815 / 7915 before OPamps, my bad. So it would be probably safe enough to use the 18VAC PSU if we consider only a bit more heat on the regulators.