PSU 3 BitsHelp Pls

[Pingushome]

I am building a PSU3 to power a Pre2 CF. I have just ordered the PCB form Mathew so any advice on diodes and caps would be helpful, types and suppliers etc. I will be changing the zener as FAQs but the small bypass cap recommended there, what kind should it be? Is it worthwhile upgrading the the voltage reg to the more powerful version?
I have a circuit diagram for the PSU3 I found on the forum and Richard kindly explained the different way the PSU3 places the smoothing caps, but any other advice would be very helpful.
Thanks Martin

[Richard]

Hi Martin, do you have both PSU2 and 3 circuits to work from ok?

Have a look down this longish thread,

http://www.world-designs.co.uk/forum...ght=schottkies

which should have some part numbers in, I went for schottkies on heater and HT and LDO regulator as mine powers Pre3 and Phono3.

Your later PSU3 pcb will probably come with space for individual heater diodes save making the bridge.

I later filled the other 2 caps spaces and there's loads of room to do what you need.

[colin.hepburn]

Hi martin
Yes many of us use fast recovery Diode in the PSU2 HT I can’t see the part numbers for them on my psu2 but they are the TO-220 type case
I think Richard will still have the part number and some did change the voltage reg to the more powerful version buy I think it depends on what you wall mains voltage is and if you are using the phonofrom the psu2 as well and here is the links for the heater upgrade we did as well that Richard came up with
Hope this helps in part

http://www.world-designs.co.uk/forum/showthread.php?t=4158

[Pingushome]

Hi Both,
Thank you both for the very helpful advice and the pictures were so informative, always easier to see what it should be like than to explain. (especially to a novice). Yes I have down loaded the curcuit for the PSU3 from here and I still have all the instructions from the Pre2 Psu2 kit I bought long ago. I found the string on the diodes helpful, I think I know where I am going now. Martin

[bob orbell]

Hi Martin, just some more advise, if you are using the four diode option, which is best, bypass each diode with a 10nF film capacitor of equal voltage to the diode voltage rating, both HT & LT, allso a snubber across the choke, comprising, two 220nF 400v capacitors, back to back with their C/T conected to 0v, all helps to stop ringing. BOB

[Pingushome]

Hi Bob, Thanks for the advise. Two questions tho. 1 are the 10nf and 220nf caps any film or polyprop types and 2 although I am aware of bypass caps how do I make the snubber for the choke? Sorry if that is a numpty question but I am at a very basic knowledge level. I may ask some more details later as I see you have a Pre CF wirh a relay board input and that is what this PSU will ulitmately be used with. If you would be kind enough to hold my hand throught the build. Thanks Martin

[Pingushome]

Hi Everyone,
The project is taking shape at last. I have ordered some bits from RS and Hong Kong (lader atten) for the PSU 3 and the Pre2/3 cf.
Hope it arrives and the attenuator is not a rip off spoof
Mathew has been very heplfull and supplied other bits for the cf pre Photos when all is completed (eventually).
One question would these diodes for RS be ok for the heater supply in the psu STTH512D it says they are 1200v 5amp Ultra fast recovery diodes? If not any help / info would be appreciated
Martin

[Richard]

Hi Martin,

They would work but better choices would be schottkies in both locations which have no recovery current or voltage, effectively noiseless, and so don't need caps across them.

New ones come along all the time. Below are the same heater diodes I used and the later version of the HT diodes. There is also a good fast and soft switching alternative for the HT if you don't fancy spending £20 on a set of schottkies, here from RS,

For HT RS 702-7462 600v 6A Schottkies C3D06060A

http://docs-europe.electrocomponents...6b80e2c1a6.pdf

Cheaper alternative for HT 600V 8A ultrafast soft recovery RS 738-5207

http://docs-europe.electrocomponents...6b80f8c96e.pdf


For heaters RS 687-0877 1N5822 40V 3A

http://docs-europe.electrocomponents...6b80da3e31.pdf

[Pingushome]

Hi Richard,
Thanks for the advice I think I will go for the "value" option for the time being. Costs seem to be esculating a bit at the the mo.
Will order the other bits soon. Lader atten arrived today not best qual but should be ok
Martin

[Pingushome]

Hi Richard,
Another couple of questions (sorry).
1. I see you use 150uF caps in the 3psu, looking at the RS site I see some Panasonic, Rubicon, Nichicon caps rated at 450v DC. will these be OK to use?
2. I am using the uprated voltage Reg LM1084IT-5.0, is this a staight plug in. The way I read it is if the reg faces the rear of the board (that would be at the rear of the psu box) it is a straight fit. Looking from the rear of the board left pin conected to C6 pos terminal D5/6, center pin to pos terminal of C7 and heater +, right pin to heater - via R8 and R9?
Hope I made that clear. Sorry to be so nieve but jst checking.
Martin