6v & 90v DC Power supply
in [Design]
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From: w_tom on 28 Dec 2005 14:25 Actually SGS Thompson that specifically makes protectors for automobiles and load dump (do what 'too small' transzorb would also do) acknowledge in their app notes that: > " ... there are several existing products products able to > clamp this overvoltage at the board level, for example the > LDP24 or RBO series. The protection at the alternator level > is a quite new concept and all the technical problems do not > seem to be completely solved." This would explain why an 'up to 270 volt' transient is not routinely observed. Still, automotive electronics typically should withstand about 50 volts ballpark without damage. Transzorb could be but one part of that protection system. Or a DC to DC converter that specifically has such protection could be obtained. A weakness of Transzorbs are their low power abilities. The advantage - those avalanche diodes can handle so much more power than conventional zeners. My first design that used Transzorb was maybe 20 years ago. GS was selling Transzorbs even long before then. Load dump does not occur frequently. But that one time can be so destructive. Best to consider load dump when attaching any electronics to automotive power because even trivial protection does so much. Rich Grise wrote: > This is what transzorbs > http://www.vishay.com/docs/88301/15ke.pdf > and hash chokes are for. > > I'm not affiliated with Vishay, formerly General Semiconductor, > just a satisfied customer. I've used them to protect circuits > against the transients caused by a 5 KV arc in an ion gun. :-)
From: gb on 28 Dec 2005 14:39 "James F. Mayer" <jfma(a)ix.netcom.com> wrote in message news:Hg1sf.10532$nm.866(a)newsread2.news.atl.earthlink.net... > I need to generate 6v DC and 90v DC from a 12v DC automotive > electrical system to power an RT-70A/GRC surplus military radio. I need > about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking > about using the guts from an old battery back up but it would be a bit of > a kluge. Are there any 90 volt regulators in the 78xx series? How do I > get the voltage up to where I can get something that I can get the 90 > volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off > the battery should work for that unless any of you can see a problem doing > that. Maybe the common common would be a problem. Right now I'm running > it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be > able to go portable with it. You will find a number of solutions (e.g. battery radios) in the Usenet group: rec.antiques.radio_phono gb
From: Joerg on 28 Dec 2005 17:03 Hello Rich, > > It seems like, no matter how closely you try to mimic the waveform of a > real instrument,... I have a feeling that this is exactly the problem. Engineers try to mimic the output waveform instead of looking how the real instrument is built. If they did that, they'd try to emulate all the individual parts and pieces. Regards, Joerg http://www.analogconsultants.com
From: clifto on 28 Dec 2005 17:29 Rich Grise, but drunk wrote: > "... Accurate imitation of the Hammond sound with simple electronic > circuitry was difficult, because the subtly-changing phase relationships > between tonewheels could not be easily replicated...." > > OK, fair enough. :-) > > I guess a piano is even harder - they don't even reproduce well from a > live recording! :-) I heard a decently accurate electronic piano sound long before I heard anything remotely resembling the timber of a B3. Still haven't heard anything that sounds exactly like a B3 (other than an A100 or another B3). -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin.
From: Rich Grise on 28 Dec 2005 20:06
On Wed, 28 Dec 2005 22:03:48 +0000, Joerg wrote: > Hello Rich, >> >> It seems like, no matter how closely you try to mimic the waveform of a >> real instrument,... > > > I have a feeling that this is exactly the problem. Engineers try to > mimic the output waveform instead of looking how the real instrument is > built. If they did that, they'd try to emulate all the individual parts > and pieces. > > Regards, Joerg > > http://www.analogconsultants.com Yabbut, how many gyrators and phase shifters and stuff does it take to model, for example, a bowed string? ;-) Thanks! Rich |