[MortenT]

Hi Paul

At last!!!
Here is my finished Diy SR7 build.

1.   PR3EHD-18v5 SR7 version
2.   Transformer from Canterbury windings
3.   24 x Panasonic FC 3300uf 35V = 79200uf
4.   DC cable, 3 x 1.5 square mm heat resistant rubber insulated wire, individually shielded and insulated with Teflon tape. Then braided very tight.









I have not made an AC cable yet, because I have no earth in my wall socket.
I am planning to make a dedicated cable, directly from my electricity meter to my Hi Fi, with its own earth.
When that is done, I will change the AC cables on all my equipment.

Before powering it up, I have some questions:

1.   My transformer has 2 x 18V secondary’s Red / Yellow + Black / White.
        Is it right? If I connect it like this:
        Red 1. Yellow 5. Black 2. White 6.
2.   How big a fuse is needed?
3.   Shout I adjust the 18.5V before I connect it to my Mac mini, or under load?

All the best

Morten

Denmark

[Paul Hynes]

Hi Morten,

Nice build!

To answer your questions,

1)   Red 1. Yellow 5. Black 6. White 2.
2)   3.15A time delay
3)   Adjust to 18v5 before connection to the Mini.

Let us know how you get on with the sound quality with your new power supply.

Regards
Paul

[MortenT]

Hi Paul

Thanks a lot

Best regards

Morten

[paul79]

Bitchin work man!

One question... Does this supply have a soft start feature? Seems like a lot of capacitance for a toroidal transformer.

[MortenT]

Hi Paul

Initial impression is amazing, the whole soundstage is more transparent and bas is more firm.
I will leave it on for at least 14 days and see if that is enough burn in.

Paul79
Thanks for the kind words.
No, there is no soft start, and I don´t know if it is needed.
Maybe we should ask Paul Hynes that question.

Regards

Morten

[Paul Hynes]

Hi Morten,

Paul79’s suggestion is sound. I would be inclined to fit a soft start for long term reliability with the capacitor bank you have fitted, as the inrush current will be high. The high current rectifier used on the regulator module is specified for 40 Amps continuous and a maximum transient current of 400A for 10ms. I have asked the transformer manufacturer and he also thinks that a soft start would be a good idea as toroidal transformers can deliver heavy switch on surges.

Regards
Paul

[kenreau]

Fantastic job, Morten!

Would you mind sharing your approximate parts build cost?

Thanks
Kenreau

[MortenT]

Hi Paul

In that case, I better build me a Soft start.
Du you have a suggestion on how to do a prober on?


Kenreau

Here are the main parts

PR3EHD-18v5 SR7 version costs £141
Insured carriage and packing for one or two modules is £15 to Europe

Transformer from Canterbury windings:
Power rating: 250VA
Primary: 0-230V @ 50Hz
Secondaries: 2 x 0-18V @ 6.94A rms
Regulation: approx 8%
Estimated dimensions:  112mm diameter away from leadouts x 59mm high
Mounting: standard mounting kit (adds approx 4.5mm to the height)
Leadouts: approx 200mm long flexible (stranded)
Audio grade construction

Price for 1 off: 48.45 GBP + 22.00 GBP carriage (FedEx) + 14.09 GBP VAT = 84.54 GBP

From RS-Online:
158-578      1. Heatsink 0.6K/W 100x100x32mm anodized £15.48
315-0798    24 x Panasonic 3300 μF ±20 % 15 mΩ 35 V dc Through Hole Radial Aluminium Electrolytic Capacitor £35.37

+ Plugs, switch, wires and chassis


Regards

Morten

[Paul Hynes]

Hi Morten,

I am in the process of preparing a soft start module for my SR10 ATX Linear power supply. This is designed to safely energise transformers up to 1KW and will have automatic re-start when power is restored after a power cut. As it is a separate module from the ATX control interface module it would be usable separately for your power supply build. I still have some work to complete the ATX control interface module and once I have this operational I will be sending the pcb layouts for board manufacture. Not sure how much it will cost yet, or long it will be at present, as I am very busy. It could be several months before the module is available.

Regards
Paul

[paul79]

That would be a great thing to have for sure. In the meantime, you could get by with a good ICL (Inrush Current Limiter).

[MortenT]

Hi Paul

That is a very interesting project, looking forward to hear about it.

Meanwhile, will this do?
http://electronics-diy.com/soft-start-for-power-supply.php

Ore shout I rather by this on?
http://www.lcaudio.com/index.php?page=315

There are of course several Chinese options
http://www.aliexpress.com/store/product/220V-High-power-Amplifier-soft-start-board/800514_579801319.html

http://www.ebay.com/itm/30A-soft-start-protective-anti-collision-board-for-HIFI-Stereo-Amplifier-220v-/121033350718

Regards

Morten

[paul79]

The one in the second link is all you need. I believe any of them could do the job though.

[flowerpot]

PR3EHD-18v5 SR7 version costs £141
Insured carriage and packing for one or two modules is £15 to Europe

Transformer from Canterbury windings:
Power rating: 250VA
Primary: 0-230V @ 50Hz
Secondaries: 2 x 0-18V @ 6.94A rms
Regulation: approx 8%
Estimated dimensions:  112mm diameter away from leadouts x 59mm high
Mounting: standard mounting kit (adds approx 4.5mm to the height)
Leadouts: approx 200mm long flexible (stranded)
Audio grade construction

Price for 1 off: 48.45 GBP + 22.00 GBP carriage (FedEx) + 14.09 GBP VAT = 84.54 GBP

From RS-Online:
158-578      1. Heatsink 0.6K/W 100x100x32mm anodized £15.48
315-0798    24 x Panasonic 3300 μF ±20 % 15 mΩ 35 V dc Through Hole Radial Aluminium Electrolytic Capacitor £35.37

+ Plugs, switch, wires and chassis


Regards

Morten

Paul sells diy kit ? I would be interested to build my own PSU.

[MortenT]

Hi Flowerpot

Paul do not sell Diy. kit´s.
I have sourced this from various shops.

Paul79

Thanks a lot, I have already ordered on.

Regards
Morten