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From: Joerg <news@analogconsultants.com>
Newsgroups: sci.electronics.design
Subject: Re: KA7500 vs TL494
Date: Tue, 8 Apr 2025 21:22:37 -0700
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On 3/25/25 6:25 AM, legg wrote:
> Chinese commodity power supplies have tended to use recognizable
> configurations from times gone by. In doing so, it's easy to
> miss some of the 'small stuff' that actually produced a reliable
> product, in the day.
> 
> Even more so, when pricing reaches the 'replace vs repair' threshold
> - why even bother with burn-in, in that case? If no burn-in or field
> return failure analysis is ever consudered, the small errors persist,
> particularly if vendors play wack-a-mole with the same hardware
> offered under different brand names and paperwork.
> 

Burn-in? Doesn't that happen at the customer? :-)


> Case in point is a 5V 40A unit advertised 'for use in LED sign',
> commonly used in Onbon product. In the application where a repair
> or replace decision was made, actual consumption was in the 35W
> range, though a test sequence could draw much higher power.
> replacement with an identically rated unit was Cdn$22.00.
> 
> The replacement was physically and schematically identical, but
> relaid as a mirror image for component placement. Different
> brand name.
> 
> Anyways - a basic self-oscillating bipolar transistor half bridge
> with forced beta, synchronized/steered and pwm'd by opening and
> shorting the resistor-limited, center-tapped 'drive' winding.
> Open collector drive out of a KA7500.
> 
> What's a KA7500 ? Turns out to be pin compatible to TL494, but
> mfrd by Samsung/Fairchild/ONS.
> 
> http://ve3ute.ca/query/TL494_vs_KA7500.pdf
> 
> Oodles of data and apps for the 494, not so much for the 7500.
> If anyone's got app info published for the KA7900, in any
> language, I'd be interested to see it.
> 

You mean a datasheet? It's here:

https://www.mouser.com/datasheet/2/149/KA7500C-89501.pdf?srsltid=AfmBOoqgRNYOTol-O6pVSUwQ0v07-Tqdgmcnph3f_Uq5xj18Tvq5uAYY

[...]

-- 
Regards, Joerg

http://www.analogconsultants.com/