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Hi Board!
noticed the 12V/5V DC/DC AP63357 has probably some body diode from output (Anode) to input (Cathode)
Sometimes the circuit is powered directly with 5V, so the 12V relais and 12V lights at the 12V rail are now powered (ca 5V-0.4V @400mA) by this intrinsic diode.
Should I be worried that...
Hi all,
just wanted to update and say that I found the actual problem and came up with the solution and tested it and it works fine.
The real test in the real world should show if this fix is viable or not, but having found the issue I think it is a permanent fix.
As mentioned, some of these...
Thanks for the suggestion.
Knowing how busy you all are I try to make it as easy as I can.
That's why I read the FAQ's and guidelines and prepared the schematic etc.
Just downloaded that program and am getting acquainted with it.
Will use it for future pictures to amend the text into them.
GetDeviceInfo, you are very right, I took some pictures which I will attach here.
Some sweeps get wider with R6.
But it leaves still the question on why they did that.
Rsc is indeed 0,1 ohm, both on the package and measured at several units.
In the beginning, while searching for the reason of...
FvM: I have been operating the unit with the 1.2nF "fix" (between pin 3 and pin 7 of U1) for nearly 24h, and all is well so far.
I will heat it up tomorrow and if it stays stable I'll do the addition to the "Quad "unit too.
The "quad" unit has a 4 stroke hickup and gets very hot.
There are...
I added some more pictures in the above mentioned thread.
**broken link removed**
**broken link removed**
I did add 1nF and 2nF as you, pisoiu, and somebody in the other thread suggested. The cycles grew a little longer, but the weird pattern stayed.
FvM, I removed C8, it had no effect on...
I would love to replace the whole thing, but as mentioned, this is not possible.
This is an existing design deployed in may (poor) countries, and any fix must be done with minimal tools and efforts.
We can add parts on top of some of the parts, but removing them in general is not possible.
I...
Hi,
I made some measurements and updated the schematic.
The capacitors were EKZE250ETD types from United Chemi-Con and died after less than a year.
The toroid is in part covered by that nasty glue, so the windings are an interpolation of what I could count. Tried to be as exact as possible...
mc34063a coil
Hi, reducing consumption is not possible, but I might be able to add some coils to the existing, would that help?
Meanwhile I made the schematic, there are some more questions pelase:
What can be done to make the circuit more stable against different brands of the 34063?
What...
mc34063a
Hi,
I have to amend an existing circuit consisting of a MC34063A and a P-MOS switch.
It is a downconverter, from 12V to 3.3V/1.5A .
I, like you, do this out of helping and am not being paid. This is for a good cause.
The circuit has a coil which gets extremely hot, so hot, that it...
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