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- From: smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC)
- Newsgroups: sci.electronics
- Subject: Re: A much better power inverter design
- Date: 11 Sep 1992 08:09:22 GMT
- Organization: SunConnect
- Lines: 35
- Sender: smckinty@France.Sun.COM (Steve McKinty - Sun ICNC)
- Distribution: world
- Message-ID: <18pk7iINNkvd@grapevine.EBay.Sun.COM>
- References: <BuE4p8.5Bq@acsu.buffalo.edu>
- NNTP-Posting-Host: hardy.france.sun.com
-
- In article <BuE4p8.5Bq@acsu.buffalo.edu>, v064mb9k@ubvmsb.cc.buffalo.edu (NEIL GANDLER) writes:
- >
- > I am a sophomore engineering student and have been researching and
- > trying to develop a new type of car amplifier that runs cooler and
- > the taim was at the power supply.
-
-
- > So I tried a mechanical method using 2 high
- > speed quality relays. The design amazingly worked with little problems,
- > like noise from the 60-hz modulated relays, a small amount of magnetic
- > intereference which can be solved and slightly warm relays. The only
- > major problem I can see is reliabilty. How many cycles can a relay take
- > before they burn out, thats the only question. I must do more work and
- > improve on this.
-
-
- That technique was actually widely used in the pre-transistor days, when vibrator invertors were used to step up 12 & 24v supplies to a level which
- would drive valves (tubes). It seems to have fallen into disuse with
- the arrival of power transistors.
-
- I don't mean that to sound discouraging, it often happens that an old
- technology revisited with modern techniques can turn up surprises. A
- quick scan through a catalogue shows that low-power relays seem rated
- at about 150,000 operations, high-power ones at 20,000,000. That is
- probably limited by a combination of metal fatigue & contact burn.
-
- Perhaps trying to find some old vibrator supplies would give parts better
- suited to experimentation.
-
- I am a bit surprised that transistors would get too hot. In a pure switching
- supply they are either fully on or fully off, and even putting 20A through
- a fully on transistor should only cause it to dissipate 16W or so, which
- a smallish heatsink should be able to cope with.
-
- Steve
-