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From: collie@ubvmsd.cc.buffalo.edu (collie)
Newsgroups: sci.electronics
Subject: Re: 12V to 5V DC conversion (for TTL logic in car) wanted
Summary: Very little
Keywords: To3 Package
Message-ID: <30452@eerie.acsu.Buffalo.EDU>
Date: 12 Jul 90 04:31:18 GMT
References: Experience
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In article <1990Jul12.024412.122@mintaka.lcs.mit.edu>, streeter@theory.lcs.mit.edu (Kenneth B. Streeter) writes...

>Some of you may recall a previous query concerning building an
>electronic odometer for my car.  (The application is TSD rallying.)
>Well, I've pursued a number of ideas, and still haven't really reached
>a decision.  However, I am having power supply difficulties with one
>of my test circuits.

>Driving the entire circuit from an external 5-volt supply (bypassing
>the regulators) indicates 1.26 amps of current being drawn.
>Basically, I'd like a trouble-free, reliable 12V to 5V converter that
>can push maybe 3 amps of current, and handle the switching transients
>in the circuit.  Any suggestions?

                         **********************

        Hi,Kenneth in your case the circuit is sagging the power supply.I
 would use a"To3"package 5 volts regulator instead of the 7805.I think with
 the correct regulator providing the voltage and current you might only need
 one To3 package for the job.The To3 package should be able to handle current
 close to what you want.However,I'm not sure about current output of the
 beast,as I don't have my stuff with me,and also make sure too filter the
 input line to the regulator from those nasty spikes.I used one to power about
 eight TTL(not CMOS mind you),and ten LED,and a display no problem.

             'ps,you might need a heat sink for that beast !!'

                         ***********************

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                               collie.
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