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a suitable transistor substitution for Delite amp
a suitable transistor substitution for Delite amp
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Old 5th June 2018, 11:16 PM   #21
gmurray618 is offline gmurray618  United States
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Thanks, both of you.
Just to take it one step further, when the voltage on the base increases making the transistor more conducive the voltage across the collector-drain might go down towards 2V and the voltage go up when the gate voltage decreases.
Correct?
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Old 5th June 2018, 11:29 PM   #22
aspringv is offline aspringv  Australia
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a suitable transistor substitution for Delite amp
Might I suggest you read - http://www.firstwatt.com/pdf/prod_f5_man.pdf for an excellent primer in how that fet is working.
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Old 6th June 2018, 12:10 AM   #23
gmurray618 is offline gmurray618  United States
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Thanks. Iíll re-read it for the first time.
The F5 was my first build and learned a lot. That was about 5 years ago and Iím sure I will get a much better understanding studying it now.
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Old 6th June 2018, 01:59 AM   #24
tsmith1315 is offline tsmith1315  United States
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Quote:
Originally Posted by gmurray618 View Post
So I was looking at transformers (100 VA 20V)
George,
I don't remember the exact details, but a stereo De-Lite is wonderfully inefficient and requires a transformer in the >600VA range.




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Old 6th June 2018, 02:06 AM   #25
aspringv is offline aspringv  Australia
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a suitable transistor substitution for Delite amp
Possibly something like DC60V 350W 5.9A Switching Power Supply 115V/230V to Stepper Motor DIY CNC Router 705701867807 | eBay might be a markedly cheaper option than the requisite transformer...

Possibly safer too. You could prep each in such a way to make the mains impossible to access. Either seal it in silicon after attaching, or box them up.

You know, the more we discuss this, the more I am wondering if the ACA is a better option. Safe, complete, relatively cheap (and certainly a bargain for what you get!) and superbly documented.

Last edited by aspringv; 6th June 2018 at 02:09 AM.
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Old 6th June 2018, 05:24 AM   #26
PRR is offline PRR  United States
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What power output do you NEED ??

Remember the motto of some wise guy: "First Watt! (is most important)". You really can get a lot of pleasant sound with only one Watt.

The resistor- (or lamp-)loaded scheme is about the worst possible for efficiency. If you aim for many-Watt levels, it scales to many-many Watt supplies and sinks. Pass was thinking of semi-affluent hobbyists, not an under-funded school.

The ACA is a much lesser investment, intended to suck victims into addiction. Ummm, spread the joy with the timid?
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Old 6th June 2018, 02:23 PM   #27
Pascal Nguyen is offline Pascal Nguyen  Australia
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Originally Posted by WalterW View Post
It doesn't look very well sanded?
Yes indeed,
It was my first hand experience in building an audio amplifier, that copper plate is warped as you can see by the wet sanding on a piece of 10mm glass.
A learning curve fo an amateur like myself (without the Pass Labs forum, I never could understand about bias, positive feedback and sit).
My first amp did not sound like an angel as expected due to the use of mosfet (the IRFP7430 i got at hand), but perseverance, patience and passion would help me to enjoy the audio diying, that how my environment is.

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Old 6th June 2018, 09:23 PM   #28
gmurray618 is offline gmurray618  United States
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Quote:
Originally Posted by tsmith1315 View Post
George,
I don't remember the exact details, but a stereo De-Lite is wonderfully inefficient and requires a transformer in the >600VA range.




There are some who call me...
I did the math from Nelsonís Zen 1 article and found that Iím good with the 100 VA - IF I ONLY WANT ONE CHANEL DíOh
56V x 0.8A x 2 bulbs (one on each channel) x 2 channels 180 VA
So a 200VA 20V Toroidal it is.

And yeah the ACA would make my life easier, as farr as cost it seems to be about a wash at this point. Iím sticking with the Zen for its simplicity and the non-kit aspect. Remember this is a teaching tool (not just a gateway ÖÖÖ to diy )
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Old 6th June 2018, 11:49 PM   #29
tsmith1315 is offline tsmith1315  United States
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My mistake, I was still thinking De-Lite. I didn't realize you were leaning towards Zen-Lite.
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Old 7th June 2018, 08:30 AM   #30
aspringv is offline aspringv  Australia
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a suitable transistor substitution for Delite amp
Sadly, I'm afraid not!

If you read through a few of the first watt articles you'll realise you're going to need a lot more transformer than that...

Quote:
Originally Posted by gmurray618 View Post
I did the math from Nelsonís Zen 1 article and found that Iím good with the 100 VA - IF I ONLY WANT ONE CHANEL DíOh
56V x 0.8A x 2 bulbs (one on each channel) x 2 channels 180 VA
So a 200VA 20V Toroidal it is.

And yeah the ACA would make my life easier, as farr as cost it seems to be about a wash at this point. Iím sticking with the Zen for its simplicity and the non-kit aspect. Remember this is a teaching tool (not just a gateway ÖÖÖ to diy )
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