From: David Cole (DavidCole@tk7.net)
Date: Thu May 01 2003 - 06:48:06 PDT
That good info. I was concerned that these devices might become fuses. I
also didn't know you could parallel those devices.
Dave
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
On Thu, 1 May 2003 07:53:47 -0400, Steve & Jeanne Keith <cckw@attbi.com>
wrote:
> I use to design power supplies with these 78xx and 79xx regulators.
> They will shutdown from over current or over temp. As someone
> stated, the power dissipation in Watts is what will get to them 1st.
> They need to be heat sunk using a mica washer and special thermal
> compound to transfer as much heat as possible.
>
> You should also put on each .01-.1 mf capacitor between the input
> terminal
> and the ground terminal and the output terminal and the ground terminal.
> They have a tendency to become an oscillator and that causes problems!
>
> JC Whitney sells a version of this for gas gauges. It is mounted on a bar
> that has a hole in it to attach to the gas gauge. The other end of the
> bar
> has a stud to attach the power feed for the gauge. There is a wire coming
> off the bar that needs to be grounded. Theyse units run about $18 and are
> probably worth it when using 12v on a 6v vehicle.
>
> Steve AKA Dr Deuce
>
>
>
> ----- Original Message ----- From: "TA2 CNU" <ta4cnu@hotmail.com>
> To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
> Sent: Thursday, May 01, 2003 7:16 AM
> Subject: Re: [MV] 6volts from 12 or 12v from 24 volts
>
>
>>
>>
>>
>>
>> two or more 78XX or 79XX can be used in parallel, if the outputs are
>> connected to a terminal with a i.e. 0.2 Ohm 5Watts resitor; more
>> adviced
> to
>> use power transistors after the unit... then it gets complicated...
>>
>> ta2cce
>>
>>
>>
>>
>>
>>
>> >From: David Cole <DavidCole@tk7.net>
>> >To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
>> >Subject: Re: [MV] 6volts from 12 or 12v from 24 volts
>> >Date: Wed, 30 Apr 2003 23:16:08 -0500
>> >
>> >I've used those before but in a controlled situation - ie. soldered
>> into
> a
>> >PC board, feeding some ICs, etc. How do they standup to overloads, and
>> >electrical noise. If they are rated for 1 amp, do they open circuit at
>> 2
>> >amps, etc?
>> >
>> >Dave
>> >
>> >On Wed, 30 Apr 2003 10:37:16 -0700 (PDT), w7ls <w7ls@blarg.net> wrote:
>> >
>> >>Yes, those will work. They are available in higher power packages,
>> under
>> >>different numbers. If you draw more juice through them for more lights
>> >>or whatever, they will give off more heat, so a heatsink is a must.
>> See
>> >>Digikey.com, Jameco.com, Bgmicro.com, or if you're really desperate,
>> >>Radio Shack. Jim
>> >>
>> >>"TA2 CNU" <ta4cnu@hotmail.com> wrote:
>> >>
>> >>>LM 78XX (xx= 06 for 6 volts, 12 for 12 volts)(negative ground)
>> >>>
>> >>>a simple transistor like chip can be used for getting 6 volts from 12
>> >>>volts or 24 volts and 12 volts from 24 volts; but up to 1/2 amps. A
>> >>>decent cooling fin will be needed...! (will cut out in case it gets
>> too
>> >>>hot).
>> >>>
>> >>>this is a three legged item :
>> >>>left leg + volts in,
>> >>>mid leg - gronund,
>> >>>right leg + volts out.
>> >>>
>> >>>also:
>> >>>LM 79xx (xx= 06 for 6 volts, 12 for 12 volts)(positive ground)
>> >>>
>> >>>
>> >>>
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>> >
>> >
>> >
>> >--
>> >Dave
>> >
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>
>
>
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>
-- Dave
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