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Old 22nd Oct 2019, 11:35 pm   #1
Jolly 7
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Default DIY 18VDC power supply for Hacker Sovereign II

Here is an 18V DC power supply I put together in an old Philips battery eliminator case. I did not have to change the transformer, which was 18-0-18V. I was also lucky to find a cord from another old wall wart with the exact slim DC plug that fits perfectly in the recessed Hacker DC socket. The heatsink hardly gets warm after over an hour over constant use. I've screwed back the cover of the eliminator. A perfect fit with functionality.
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Old 23rd Oct 2019, 1:48 am   #2
Boulevardier
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Default Re: DIY18V DC power supply for Hacker Sovereign II

That's neat! Do you get any zero-volume mains hum on the Hacker? They do seem to be quite sensitive to it (and I suppose with a PA input sensitivity of 50mV, they are entitled to be!). My RP25A has some from it's VP408, but I suppose with 50-year-old components, I need to check a few of them.

Mike
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Old 23rd Oct 2019, 8:54 am   #3
Jolly 7
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Default Re: DIY18V DC power supply for Hacker Sovereign II

Thanks Mike. I have no hum on FM, MW and LW using my circuit. I also ran the radio from another DIY power supply using an LM317 and there is no hum either. I have seen pictures of the VP408 but am not sure what might be causing the hum. If it is difficult to repair, making a supply similar to mine is inexpensive and easy. The main expense would be the transformer and housing, unless you are able to use your existing one. In addition to the Philips transformer and housing, I used a PCB from an old surge protector and the DC cord with the correct plug cut off an old wall wart.
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Old 24th Oct 2019, 8:38 am   #4
Boulevardier
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Default Re: DIY18V DC power supply for Hacker Sovereign II

Thanks for that. I probably wasn't very clear - I should have said that the hum I mention is very low level - just about audible in a quiet room and slightly less than you'd expect from an old valve receiver in good nick - so very low. But I wouldn't expect even that low level from a solid-state receiver and amplifier with regulated PS. As I said, the electronics is very old (original circuit-board transferred from 50-year-old VP408), so maybe should check some components. The Hacker is far from being useless with the slight hum, but still we must strive for perfection...!

Mike

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Old 24th Oct 2019, 9:00 am   #5
dazzlevision
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Default Re: DIY18V DC power supply for Hacker Sovereign II

The Philips unit is an N6502, originally with three dc output voltages: 6, 7.5 and 9V @ 250mA max. The mains lead into it is pluggable and the "hard wired" dc output lead is terminated in a "Roka" plug, with an adaptor to convert it into a 5 pin (270 degree?)DIN plug, that was fitted on many Philips portable battery only cassette recorders.

It uses a typical series regulator circuit, with a zener diode voltage reference. Transistors AC128 and AD162.

They are well made and seem to be widely available on auction sites, etc.
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Old 26th Oct 2019, 1:02 am   #6
Jolly 7
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Default Re: DIY18V DC power supply for Hacker Sovereign II

Quote:
Originally Posted by dazzlevision View Post
The Philips unit is an N6502, originally with three dc output voltages: 6, 7.5 and 9V @ 250mA max. The mains lead into it is pluggable and the "hard wired" dc output lead is terminated in a "Roka" plug, with an adaptor to convert it into a 5 pin (270 degree?)DIN plug, that was fitted on many Philips portable battery only cassette recorders.

It uses a typical series regulator circuit, with a zener diode voltage reference. Transistors AC128 and AD162.

They are well made and seem to be widely available on auction sites, etc.
Very well spotted, thanks. Yes it is an N6502 indeed, made by Philips in Holland. It was hiding inside the battery compartment of a Roberts RT1 and was being used to power the radio at the 6V setting. It has a dual mains voltage selector too. I have the circuit diagram for it in case anyone's interested.
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Old 28th Oct 2019, 5:29 pm   #7
Welsh Anorak
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Default Re: DIY18V DC power supply for Hacker Sovereign II

Don't forget these Philips transformers often had a thermal fuse inside that's easily resoldered, thank goodness, but often failed for no obvious reason. Just in case things go quiet unexpectedly...
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Old 28th Oct 2019, 6:47 pm   #8
Jolly 7
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Default Re: DIY18V DC power supply for Hacker Sovereign II

Thanks Glyn. I'll bear that in mind.
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