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Author Topic: New Member and a question  (Read 8352 times)

g1

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Re: New Member and a question
« Reply #30 on: July 05, 2014, 01:59:19 PM »
  Sorry to nitpick, but standard "safe" wiring of fuseholder is for incoming power to go to back end of fuseholder first, then out the side.  This is so as soon as the fusecap is disconnected the hot can no longer touch anything.  With the hot on the side terminal like you have it, as the fuse is being pulled out it can contact the "hot" side terminal.
Of course we assume the unit will be unplugged before the fuse is removed, but mistakes happen.

BrianS

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Re: New Member and a question
« Reply #31 on: July 05, 2014, 05:16:27 PM »
Quote
Sorry to nitpick...

No problem g1, thanks for pointing that out!  I will change it when I redo the recto and replace the optocoupler.

Quote
got real curious about what speakers were used there, got a couple pictures

If you are talking about my recordings, the speaker is an 8ohm Eminence Legend that I bought used.  Model designation is AVM-128.   

I purchased the TA-16 sans speakers.

Roly

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Re: New Member and a question
« Reply #32 on: July 06, 2014, 11:31:17 AM »
Quote from: J M Fahey
very usable at 10A.

That depends on what you mean by "usable".

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Vce(sat)min = 3V @ Ic = 10A and Ib = 3.3A

Over three amps of Base current - for only 10 amps Collector current?  They don't give any figures for the maximum current rating so we can only guess how bad they are.  Need another '3055 as the driver.

At Ic = 15A Hfe is around 10. (all the ON Semi datasheet plots actually end at 10 amps, well below Icmax which I think contains a message)

I love the '3055 like a brother, but ya gotta be realistic - these days there are far better devices at reasonable cost.
If you say theory and practice don't agree you haven't applied enough theory.

J M Fahey

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Re: New Member and a question
« Reply #33 on: July 07, 2014, 08:46:23 AM »
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Quote from: J M Fahey

    very usable at 10A.


That depends on what you mean by "usable".
I can get 10 A peak into a load with only 20 mA drive ... and that´s the "min" Factory guaranteed spec, I design with 10mA drive and it´s always enough.

Practical use: a +/-40V rails power amp with TIP141/142 outputs can put full rail voltage (minus transistor drop, some 4V and what you lose in the ballast resistors) into a 4 ohm load.

That´s why TIP142/147 are *so*  popular in major brands.

http://www.onsemi.com/pub/Collateral/TIP140-D.PDF

Roly

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Re: New Member and a question
« Reply #34 on: July 08, 2014, 04:42:15 AM »
Sorry JM, I think we've got crossed wires.  I'm saying that the 2N3055 isn't worth a crumpet above about Ic = 5 amps.

Yes, if I was looking at more than 50W or 4 ohm loads I'd be considering something else, such as the TIP 142.
If you say theory and practice don't agree you haven't applied enough theory.

 

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