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Post by Deleted on Oct 26, 2015 10:28:54 GMT
Bom for soft start....  |
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Post by MartinT on Oct 26, 2015 11:37:56 GMT
Thank you, Colin. This is a fantastic project for DIY minded members.
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Post by Deleted on Oct 26, 2015 11:47:28 GMT
Well Martin I have built a few now in different case and watched others and their progress and it is fantastic, at last I am enjoying my forced retirement and with my friend Alan we are have a great time learning again.
So thank you everybody for the fun, and keep it coming more things to do soon.
Now who's up for 2MV plasma generator?
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Post by Deleted on Oct 29, 2015 10:10:15 GMT
Just a note, please insure when you mount the LM337 and LM317 on your heatsink to use the insulating mounting kit correctly and check with meter that there are no short circuit to the heatsink from the Tab of these regulators, because it will blow fuses.
This check should also be done for all the Semiconductors (transistor and FET's)
The short circuit could be a cracked insulator or the TOP HAT that goes through the mounting hole on the LM317 or the LM337.
Do this check before you wire the PCB up to transformer and amp pcb.
If it happen after you checked it check again the first audible sign is a chattering relay. On the PSU board, this is normally a blown fuse.
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Post by Deleted on Oct 29, 2015 10:12:54 GMT
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Post by MartinT on Oct 30, 2015 8:17:19 GMT
There are some scope apps and a simple dB app for Windows Phone too.
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Post by Deleted on Nov 9, 2015 19:55:48 GMT
To improve the sound of the SECA I have removing C4 makes it sweet with guts.  |
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Post by Deleted on Nov 13, 2015 15:14:42 GMT
Here is the information on the soft start PCB. This is the BOM  These are the circuits.   Here is the PCB layout.  Here are two version the left is with spades and the right with leads and IEC connection.  Here is the spades and a EARTH TAG WHICH MUST BE CONNECTED TO CHASSIS  |
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Post by Deleted on Nov 19, 2015 18:07:32 GMT
Soft Start Configuration   |
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Post by MartinT on Nov 20, 2015 12:07:18 GMT
This is great stuff, Colin. Keep it coming!
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Post by Deleted on Dec 4, 2015 11:30:28 GMT
A few folk have been asking about the PSU board I hope this helps.  The Sliding or Dynamic PSU
As you can see the +V and –V regulator are based on the LM317 and LM337 chips, these are drive current gain stages and have a very simply current fold back current limit using 0.1R resistors to set this to about 6A. This current limit allow the 10,000uF and the SECA’ s 33,000uF capacitors to charge much slower and this will increase their life and reduce the ON thump. The basic just SECA board has a ripple voltage of about 500mV but with the PSU this is reduced to approx 5mV, this will show itself as more detail at low levels when using the PSU together with the SECA. The loses across the FET are there because we have a Gate Source voltage of about 4 – 5V so the FET cannot drive to the +V rail, the Darlington in the original has a voltage across it of about 2V and thus it cannot swing to the –V. So to use the full range of the power/volts available we use the PSU board with all the advantages mention before. In version 2 with the 2 FET’s the –V is not such a problem as we only lose about 200mV max. Now as the output approaches the max regulated +V or –V on peaks the PSU ref is also moved and as it approaches 10V peak the PSU output voltage changes and allow the FET/Darlington to get to the max voltage it can, this gives you more punch and dynamic, this will show up on deeper bass and fresh top end. |
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Post by Deleted on Dec 15, 2015 13:04:50 GMT
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Post by Mr Whippy on Dec 15, 2015 21:44:45 GMT
Colin! You're the man! You're the man for this!
The BMU thread had me thinking. If I had £500 spare, I'd buy one. But I don't. I then wondered about regenerators, which are even more expensive. I then wondered about possible diy.
Wondered what your thoughts might be.
Thanks.
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Post by MartinT on Dec 15, 2015 22:26:35 GMT
A simple regenerator (sinewave generator meets sodding great class AB amplifier working on high voltage DC rails derived from the mains) would be too big, too hot and too power hungry. My old P300 could cook eggs.
You need a smart tracking amp which only 'repairs' distortion in the waveform. Much lower power, efficient but probably tough to design.
You're right, this is a job for Colin!
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Post by John on Dec 16, 2015 5:29:36 GMT
Yes the P300 was good in the winter
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Post by Deleted on Dec 16, 2015 9:18:15 GMT
OK how many KW do you want, Oh Martin HV rail would be better but the semi costs would be high so I would go for +- 100v, and insist everybody did the tongue test. That is like a battery on the tongue but in this case 100V not 9V, this would reduce the Greenhouse gases due to the population being reduced. And therefore good for the Earth. What no takers.   |
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Post by Mr Whippy on Dec 16, 2015 23:34:21 GMT
Oh, my needs are pretty modest, I think, Colin. Out of the amps I have, the most power-hungry is a 330 watter. I also have a valve phono stage which I don't know what it's consumption is plus record deck and a cd player at less than 20 watts. .75Kw would probably be sufficient, I think.
Your photo reminds me of an episode at work which took place before I started. The factory foreman - who was an electrician, and should have known better - was one day poking about inside a junction box when he took a belt. Not only was he somewhat stunned, and face blackened. His hair was also somewhat erect. Apparently it was quite a picture to behold.
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Post by Deleted on Dec 17, 2015 9:01:17 GMT
The worse shock I had was of a beam Tetrode at 400V but at 400MHz at Plessey, it made a hole in my thumb and came out of my elbow and smoked . I was a 28yr old apprentice and I knew everything, I never did it again. The next was of a amp from another company with the Earth Live reversed as I picked it up it got me ouch. The worse bang was Picric Acid Crystals in a petri dish, it destroyed a butler sink and burnt my eyebrows off and smashed me into a wall 6ft away. I never ever found out what nitwit left them in a sink like that. Past lives. Happy Birthday Beethoven  |
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Post by Deleted on Jan 1, 2016 10:15:11 GMT
Happy New Year,
It has been a good response and some very novel and interesting builds for the SECA kit, thank you all,for all the photos.
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Post by Deleted on Jan 24, 2016 18:08:40 GMT
The new batch of PCB's are now in stock.
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