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goldenreference low voltage power supply


kevin gilmore
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Ok, quick update. Finally received transistors/FET's from flea-bay purchases,  12 -  KSP42TA from Spain, and a complimentary pairing of a MJW21194G and a MJW21193G from Germany. The Question is are they fakes?  I have an offer for someone who has the capabilities. Could I get someone to test a sample of 4 of the KSP42TA's to see if they match up to spec, and they get the 4 free for the service? They would obviously need the equipment to properly verify specs.  It seems to take a minimum of 4 for this board, and they should still be able to get the KSP92TA's from Mouser current stock. Anyone game? Would prefer continental US as I'm paying US postal.

Hoping to get some pictures of all three posted, so if anything obvious looks off ya'll might alert me. Back orders from Mouser look abysmal right now, some slated for as late as march of next year.

In other news, I did order the Haako soldering station and 2 extra beveled tips, should be in tomorrow.  It's looking like I may have to put off continuing on this board and start instead on the SuSy Dynalo boards to keep making progress. Will probably start a resistor order next week.

 

Anyway, have a great night/day!!!

 

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Pars, you are the 'Man'!!! Thank you! Ordered tonight!

 

As to the other two transistors, here's a pic of the better looking of the 2 (1st is a little scratched up).  Part numbers are printed clearly, not stamped or engraved, and the lettering in the dots is very clear and either stamped or molded, 07 and E for MJL21194 and 03 and E for the MJL21193. ETA on backorders is Dec and Feb if the current ones are fakes.

IMG_0594.JPG

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  • 2 months later...
On 12.08.2021 at 18:03, ShortBtwnHdset said:

Просто хотел дать небольшое обновление. Прогресс был достигнут, на плате частично установлены гнезда для микросхем, большинство резисторов и диодов, а также танталовые и пленочные крышки. Все транзисторы, включенные в мою покупку на ebay, подходят только для плат SuSy Dynalo, поэтому вчера вечером я сделал еще один заказ у Mouser. MJW21194G и MJW21993G какое-то время отсутствовали на складе, возможно, придется найти другой источник (Digikey также отсутствует).  KSP42TA также отсутствуют.

Это моя первая сборка, и мои навыки пайки были в лучшем случае уровнем мастера. Я понятия не имел, насколько я ржавый! Поскольку гнезда IC были в центре платы, я начал с них, и потребовалось переделать пару пэдов, чтобы понять это. Рад, что купил очиститель флюса! Я определенно не обладаю навыками производства, но теперь все суставы хорошо выглядят под лупой. Самая сложная часть, кажется, использовать достаточно припоя и не слишком много. Купили жидкий флюс для разъемов IC, здесь не было проблем, но похоже, что он понадобится для больших сокетов IC на платах SuSy.

Мне нужно начать смотреть на трансформаторы, надеюсь, на тороиды. Проблема в том, что мне может понадобиться еще одна вторичная обмотка и соответствующая плата постоянного тока для питания периферийных устройств. Я надеюсь в какой-то момент добавить такие параметры, как чувствительность входа, удаленная громкость или переключение нескольких источников. Как вы думаете, должна ли шина на 12 В, может быть, на половину ампер, покрыть эти возможности? 

Я надеюсь начать поиски в магазинах доброй воли временного футляра, перепрофилированного из какого-то другого аудиокомпонента. Просто в основном нужен листовой металл и розетка IEC (надеюсь, с держателем предохранителя), возможно, крепление для регулятора громкости и даже возможные входные разъемы или два. Я постоянно делаю, когда у меня все заработает и в голове будет картинка готового продукта. В поисках вдохновения мне приходится просматривать гораздо больше всех сборок. 

Еще не все!

Digikey suggests to replace MJW21194G/MJW21193G with MJW21196G/ MJW21195G. The only difference I've found in datasheets is lower saturation voltage.

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  • 1 month later...

Question about transformers. I have a GRLV I want to repurpose, and it’s been used with a 22VCT transformer (single bridge rectifier) which for various reasons can’t be reused. I want to use the GRLV now with an Antek dual secondary transformer. I don’t want to change the bridges on the GRLV because it’s one of the earlier PCB versions that has incorrectly sized holes on the rectifier pads and it’s annoying and messy to (un)solder all that.

1. Can I tie the secondaries together and achieve a center-tapped equivalent? This suggests that I can: https://electronics.stackexchange.com/a/571731/59134

2. There is no 11V dual secondary Antek product, but there’s a 12V (https://www.antekinc.com/as-0512-50va-12v-transformer/). This means it’ll be equivalent to 24VCT (if I understand things correctly). Is that okay for a 20V output GRLV, or too high?

I guess I could spring for a custom 22VCT transformer, but Anteks are so much cheaper and more convenient to buy.

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12V is too low for a 20V output. I'd use dual 18/18. 12V would give you 12 * 1.414 = 16.96 - 1.4 = 15.56V. I don't think the math is any different for a center tap / single bridge application, but I could be wrong.

In answer to your question, #1 is correct. You can use a dual secondary transformer configured as a CT.

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I thought that tying two secondary windings together to make a center tap effectively creates a series AC circuit, which adds together the voltages of the windings. So two 12V secondary windings make a 24V center-tapped winding. And 18+18 would turn into 36-0-36, which definitely seems too high for a 20V DC output. Is that wrong?

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1 hour ago, gepardcv said:

Right. So with a GRLV destined to output 20V, what’s the right secondary size? 12/12 gives 24V, which I’m wondering if it’s too much. I’m sure 18/18 is too much. I used 22VCT before, which was perfect and ran cool. 

Is the GRLV intended to output +20VDC or +/-20VDC? 

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  • 2 weeks later...

MJW21193/4/5/6 are all 40 to 58 weeks out now. I want to build it much sooner. I can find one at a place to order, but not the mating one. Can MJL21193/4/5/6 (which are also scarce) be used? Or something else for the pass transistors? Or does someone know of a hidden stash somewhere?

Thanks.

Sorry, I just noticed some alternatives that could be used on the part sourcing thread.

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Hi!

What changes I need to make if I want to have 40V, 2A output? I read an entire thread so I saw that another pass transistors need to be added. So 2 pairs of pass transistors (MJF15030 and MJW21194) and additional protection diode? What about increasing base current? Can somebody post a higher current design scheme? 

Best regards,

Julio

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  • 2 weeks later...
On 1/2/2022 at 6:26 PM, RonH10 said:

MJW21193/4/5/6 are all 40 to 58 weeks out now. I want to build it much sooner. I can find one at a place to order, but not the mating one. Can MJL21193/4/5/6 (which are also scarce) be used? Or something else for the pass transistors? Or does someone know of a hidden stash somewhere?

Thanks.

Sorry, I just noticed some alternatives that could be used on the part sourcing thread.

I think the MJL* versions are the same except for different leg / pin sizes and slightly different packaging. Electrically they are the same as the MJW* (I think from memory) 

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