Re: reverse polarity protection (ubitx.net)
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Sarma surely responds.
The reverse protection diode has been shown in the ubitx sch , both v3 and v4 perhaps.
I would only suggest that let us have a fuse in series to dc of say 5 amps. the reverse diode would sit after the fuse to ground.
Any accidental reverse connection , the fuse would blow and reverse voltage would not continue to the actual circuit, once fuse blows.
On Tue, Aug 7, 2018 at 1:56 PM, Mike Woods <mhwoods@...>
I will add PH2LB's reverse voltage protection solution to that
page at your suggestion. I hadn't noticed that idea previously,
but did recognise the distinctive build so I guess it is on
I am not sure about the diagram from MVS Sarma. Let's wait and
see whether he responds? He may care to redraw the diagram if he
agrees! Everybody seems to draw those sockets differently ...
Mike ZL1AXG ubitx.net
On 7/08/18 2:58 AM, Jonathan Washington wrote:
In wiring my µBITX based on the guides and notes available
this group's wiki, and the like, I noticed a discrepancy
related to reverse polarity protection.
I believe the diagram with included fuse by MVS Sarma at https://ubitx.net/ubitx-fix-reverse-polarity-protection/
has the jack wired in reverse (- tip, + sleeve) of the
standard (+ tip, - sleeve). I suppose wiring it this way
could be a good way to test if the fuse will do its job!
I should note that this solution seems preferable to the
solution(s) provided in W4RJP's wire-up diagram (v1.9) posted
, where it looks like the fuse and the diode would both blow
in the case of reverse voltage, and the reverse voltage would
still flow through the µBITX. In MVS Sarma's solution, my
understanding is that only the fuse would blow, and the µBITX
wouldn't be exposed to any reverse voltage.
Also, I wonder if Mike might consider adding to the reverse
polarity page PH2LB's reverse polarity protection solution
I haven't tried it yet, but it seems ridiculously simple,
and reasonably effective. I'd probably still want to add a
fuse with that solution, though, to protect against accidental
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