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Post by pre65 on May 4, 2016 17:21:47 GMT
Thanks for updating the chart Colin.
I shall aim for +/- 18v on the PCB (where the 33,000uf caps would be).
Now, in order to test my PSU under load conditions (before connecting to the PCB) what load resistors should I use ?
Is it as simple as 18v @ 2.5A so two resistors 7.52 ohm @ 45W (ohms law)
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Post by Deleted on May 5, 2016 7:52:48 GMT
Thanks for updating the chart Colin.
I shall aim for +/- 18v on the PCB (where the 33,000uf caps would be).
Now, in order to test my PSU under load conditions (before connecting to the PCB) what load resistors should I use ?
Is it as simple as 18v @ 2.5A so two resistors 7.52 ohm @ 45W (ohms law) That sound OK except the amp under dynamic condition draws 2.5A of the negative rail. Now the positive rail has to handle the 2.5A and the load current i.e. 5A min. When it under dynamic condition (playing music) it could demands this for 100mS or more. Just a note for a quick guide to caps 1A on 10,000uF give approx 1V Pk-Pk ripple, so with 33,000uF it will be less than 1V. The regulated power supply eliminates that for the amp board. Also the dynamic PSU I did after a output of about 10V it starts to track the output signal and drives it up to the main un-regulated rail i.e. 24V this allows the source follower design using a FET to lose the Gate - Source voltage loss and switch full on. Giving you a higher peak output power. Col |
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Post by MartinT on May 5, 2016 11:47:52 GMT
Ah, Talk Talk. More like Notalk Notalk much of the time  |
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Post by Deleted on May 5, 2016 14:01:34 GMT
Ah, Talk Talk. More like Notalk Notalk much of the time I have had for few years now with no problems but of late it is playing silly buggers.  |
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Post by Deleted on May 12, 2016 6:49:45 GMT
Sold my proto type SECA and I already miss it, so I am going to build another, without I cant play music to potter bye.
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Post by Deleted on Jun 10, 2016 9:36:00 GMT
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Post by Deleted on Jun 18, 2016 4:01:42 GMT
I have placed all and more about SECA here please add your work to help others. SECA |
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Post by John on Jun 18, 2016 4:38:37 GMT
I will be eager to see how the forum develops Colin Good luck with it
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Post by Deleted on Jun 18, 2016 6:03:48 GMT
Me too I just wanted to put everything for the SECA amps in one place.
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Post by ChrisB on Jun 18, 2016 6:43:56 GMT
Good luck with it Colin.
Do you realise that it's almost exactly 2 years to the day that you joined TAS as our first member?!
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Post by MartinT on Jun 18, 2016 7:38:01 GMT
Happy Anniversary, Colin!
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Post by Deleted on Jun 18, 2016 7:52:21 GMT
And I have enjoyed every day of it and I will not be going away sorry chaps staying on he he
As a matter if interest John is my first cool, a exchange of knowledge is good.
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Post by Deleted on Jul 12, 2016 7:24:15 GMT
The new pcb are now ready to order with the PSU SECA combined, it has got some SMD parts but I am using 1206 so not so hard to build.
This helps us all as the cost is reduced yipeee PM please.
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Post by Deleted on Aug 27, 2016 3:24:51 GMT
All those brave folk that built one of these amps be it on Vero or PCB or wire to wire, now you have I hope a chance to listen well could you please comment on you finding?
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Post by Deleted on Sept 28, 2016 6:22:06 GMT
Very Odd I replied to this yesterday before the new kitchen and minor flooding came.
Right the PCB that James uses biased up and a increase in voltage will give 50W it is in fact the original PCB which I thought I had lost the artwork for, the problem will be in the 40W version the heat sink will rise between 15 - 20C above ambient and with lovely kids about like James darling, I did not want them to get damaged,
But by increasing the bias and voltage you will get on testing 52W and a heat sink temperature increase above ambient depending on standing and clearance between 18-25C.
So the PCB we have are the same as James but will do the job so go get them lads.
But do have fun and any problem do contact me here.
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Post by Deleted on Oct 28, 2016 11:50:20 GMT
It appears that the 33,000uf @ 35V are getting harder to find, you can replace these with 22,000uF/35V or 27,000uf/35V with no change in the sound.
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Post by Deleted on Oct 28, 2016 16:05:59 GMT
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Post by Deleted on Nov 9, 2016 7:59:59 GMT
FUN FUN FUN and God loves duck to they make him giggle and with my stick I waddle also he he. Nerves now take over from pain he he.
The H.A. was due to silly practitioner telling me to stop warfarin whilst I was on Anti Bods, but the Mech Valve (not tube) jammed and bang H.A. so be warned it bloody hurts a lot.
So the next two days up the hospital for checks and the tame Vampire, (red-headed nurse jummy) .
Back in mid Novs so you lots take care best Wonf.
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Post by MartinT on Nov 9, 2016 9:03:18 GMT
I want some of what you're on, Colin Take care and all the best for your recovery to normailty. |
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Post by Deleted on Nov 9, 2016 10:59:30 GMT
Martin it just life good friends and people who love you, and lots and lots of comedy films and great music, and the sense that life is just a short comedy sketch that the universe watches has it goes to sleep.
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