Saturday, October 1, 2011

Aikido Pre-amp Project - Part 7


My bad..... Made a blunder with the capacitor multiplier schematic in the last post...

This is the correct schematic.

I forgot about the potential divider for biasing the MOSFET. My bad.

In doing so, we will reduce the B+ by 5% & also provide a short term regulation of +/-10%. Hence, smooth out sudden mains voltage fluctuation within to 5%.

In the long term sense, the B+ will track the mains voltage fluctuation.

Under New Management

In this new arrangement, the gyrator is after the CLC network filter, just like how everyone else arrange their voltage regulator.
Since we happened to have a gyrator in the circuit. Might as well let them do what they do best i.e. reduce Zo to single digit & excellent ripple reduction.
Now I can reshuffle the component values of the CLC to achieve the damping factor which I am looking for, highest B+ possible & lessen capacitance further.
Added a 220R 5W resistor in series to the choke, this was not an option earlier as it will add on the PSU Zo, with this, I can reduce 120uf to 47uf.
I could had use 10uf at the last cap, but the gyrator only mimic a huge capacitor without actually storing any real energy, so using a 47uf as reservoir seems reasonable.
Also, 3 more snubber capacitors for the rectifier, now, there is a snubber cap for every diode in the bridge rectifier. This will work better yet still not too much work...

We loss about 15V on the B+ with the gyrator & CLC amendments, but I consider that a bargain with the added slow-ramp, cleaner, stable B+, better damping pattern & reduced Zo significantly.

..........PREVIEW Part 8..........


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