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Generic Rectifier PCB - GB interest?

Got my 20 boards.
They look great.
Can't wait to start building power supplies, but maybe not the full 20 to start with :)
Many Thanks
Paul
 
Hi Rich,
my lot of boards arrived this morning.
They really do look and feel good, I look forward to stuffing them!
You did a great job.

Thanks, Ray
 
I have been looking at alternative diodes to the MBR20200CT or HFA15TB60 as these seem a bit pricey to me. Farnell have some from On-Semi and Fairchild say 8A 200v at around £1.00 to £1.50 and upwards and NXP (400v 9A for 75p)

Would these be worth buying?

There are some Vishay (see below at 91p each)


8657289
VISHAY FORMERLY I.R.
VS-HFA04TB60PBF DIODE, SOFT RECOVERY, 4A, 600V, TO-220AC

Diode Type:Soft Recovery; Repetitive Reverse Voltage Vrrm Max:600V; Forward Current If(AV):4A; Forward Voltage VF Max:1.8V; Reverse Recovery Time trr Max:42ns; Forward
 
I use the Qspeed rectifier diodes.
Search for LQA06T300, LQA10T300, LQA12T300 or LQA16T300 at mouser, they should be even cheaper.

cheers,
Lorenz
 
So anyway this project went from inception to delivery to members in just a little over a month, great going!
 
I suspect this may be a daft question as the answer may depend on the purpose to which the PS will be used. However, I wonder if there is an average value of inductor to use with these boards?
 
I've put one of boards into service already as the feed to my Starfish. I particularly like the facility they have to connect a choke before the first capacitor after the rectifiers. I've wound some hefty chokes to do just this and the results are promising.

Thanks Rich
 
I'm using approx 120mH, with about 2 ohms resistance. It needs to be that high as the Starfish only uses about 400 mA at the input voltage it is getting after regulation. The choke is wound onto an old transformer core using 9mm diameter enamelled copper. Kills mains noise dead.

John
 
John, please confirm: Do you really put a 120mH inductor in there??
(120mH = 120000uH = 12000 times the inductivity of the output stage HackerCAP inductors).
A choke with 9mm wire must be a monster. Could you post a pic?
 
Ooops, I meant 0.9mm, sorry, but it is still 120mH. Its not a air cored choke but wound onto a pretty basic iron transformer core, the sort RS used to sell as kits for 100VA transformers some years back. An air core wouldn't be impossible but the resistance would be significant. an air core wouldn't ever saturate but at these steady and low currents that shouldn't be an issue. I took the idea of a choke that would maintain near continuous current flow from Rontoolsie who put a 40H inductor before the first caps and after the rectifier in his XPS2 and reported big improvements. He built his from "recycled" loudspeaker magnets and kept the resistance down to less than an ohm. I can't quite figure how that was done.

I'll post a picture of my choke here later, its nothing fancy, but it does sound good.

John
 
Just one point to bear in mind when using a network with a choke input - you get less voltage.

A capacitor input filter, which is the kind most widely used, gives more or less the peak voltage coming out of the transformer. The current is drawn in narrow spikes.

A choke input filter gives the average voltage of the transformer waveform. The current waveform is very broad, and nearly a square wave, with a much lower peak value than the capacitor input case.
 
In fact PD that's how I knew for sure it was working and taking enough current. The output went from 1.4 * the RMS voltage to about 0.9 of it. A drop to about 63% of the peak. This was a bit tricky when driving a Traco which takes more current the lower the driving voltage. Ideally you need a higher voltage transformer.

J
 
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