ECL: Why'd they use negative voltages?
in [Design]
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From: Jim Thompson on 8 Jun 2010 18:32 On Tue, 08 Jun 2010 14:31:51 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Mon, 07 Jun 2010 17:01:03 -0700, Jim Thompson >> <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >> >>> On Mon, 7 Jun 2010 16:56:24 -0700, "Joel Koltner" >>> <zapwireDASHgroups(a)yahoo.com> wrote: >>> >>>> I realize it was the early '60s and all, but why does ECL generally use 0V for >>>> VCC and -5.2V for VEE, rather than, oh, say... 5V for VCC and 0V for VEE? >>>> Something related to how things were done when toobs ruled? (I realize that >>>> you can almost always run ECL off of 5V/0V -- and apparently this was popular >>>> practice at one time?) >>>> >>>> And why 5.2V anyway? (Granted, 5.2V is no stranger than 6.3V filament >>>> transformers, I suppose...) >>>> >>>> ---Joel >>> Noise immunity is better with 0/-5.2V >>> >>> I was there when they (Narud, Seelbach, Philips, et al) did that. >>> >>> ...Jim Thompson >> >> See.... >> >> http://www.computerhistory.org/semiconductor/timeline/1965-Custom.html >> > >Are you the guy on the right, with the wide-rimmed glasses? > ><ducking for cover> I was the young buck, right out of school, joined Motorola, working for Narud, at the very beginnings of MECL. I forgot Norm Miller and Art Capon in my list above. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Vladimir Vassilevsky on 8 Jun 2010 18:49 Joerg wrote: > But seriously, what would be the problem driving the two subwoofers 180 > degrees out of phase and reverse the connections for one of them? To the > end customer it'll be the same tchk tchk *BOOM* sound. The subwoofer is usually only one. As for the channel pairs, yes, you are right, they are often made out of phase. The only problem with that is getting it wired properly in the different configurations. > In the rare case of music that is highly asymmetrical down there a > simple limiter could kick in. So far I've not encountered H-bridges in > lower-end class-D amps H-bridge outputs are typical for the low end single IC solutions. > but then again I don't deal with audio much, I > typically re-purpose this stuff. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
From: Joerg on 8 Jun 2010 19:03 Vladimir Vassilevsky wrote: > > > Joerg wrote: > [...] >> In the rare case of music that is highly asymmetrical down there a >> simple limiter could kick in. So far I've not encountered H-bridges in >> lower-end class-D amps > > H-bridge outputs are typical for the low end single IC solutions. > I meant the really low-cost chips such as this one, the things you find in TV sets, boom boxes and other consumer gear: http://focus.ti.com/lit/ds/symlink/tpa3121d2.pdf [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Tim Williams on 9 Jun 2010 03:08 "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:dl5t069ve76vmfp6ktp3j9ci8je44q18e6(a)4ax.com... >> I encountered this problem while doing research on class D tube >>amplifiers ... > > One of the old Motorola books has a class-D amp that uses bipolar > supplies, half-bridge mosfets, LC filter, DC coupled to a grounded > loudspeaker. The problem is that, if you're swinging the load, say, > positive, you take power out of the + supply and pump power *into* the > - supply, and blow up its filter caps. Their fix was cute: an idler > circuit off to the side, a pair of mosfets switching at 50% duty > cycle, pumping V+ and V- into a dummy grounded inductor. That > automagically equalized the supply voltages. Dave Berning used that at some point. http://www.davidberning.com/technology Maybe you can find a schematic... all I see at the moment are words... I've seen a schematic before. The output section has a chopper converter turning HV toob into LV speaker (so it's not strictly OTL as claimed), and there's this bucking inductor in there, for exactly that purpose. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: Uwe Hercksen on 9 Jun 2010 03:52
Joel Koltner schrieb: > I realize it was the early '60s and all, but why does ECL generally use > 0V for VCC and -5.2V for VEE, rather than, oh, say... 5V for VCC and 0V > for VEE? Something related to how things were done when toobs ruled? (I > realize that you can almost always run ECL off of 5V/0V -- and > apparently this was popular practice at one time?) Hello, I saw a design using ECL and TTL logic together. For easier interface between ECL and TTL they used +5,2 and 0 V for ECL ICs. Only very few ECL logic was used. Bye |