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George Herold
Guest

Thu Jul 12, 2018 5:45 pm   



Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac)

I need a replacement. So either a 1 amp 7805
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF

or a LM340
http://www.ti.com/lit/ds/symlink/lm340.pdf

Is there any (practical) difference between the two? (besides the price.)

George H.


Guest

Thu Jul 12, 2018 6:45 pm   



Generally, 5 volts is 5 volts. The price shouldn't be a major concern unless you are building a million units. In, ground and out.

At ½ amp you could probably shunt regulate it, a Zener would only dissipate 2.5 watts at no load. Not efficient but probably the cheapest option.

Between the LM340XX-5 and the 7805, I'd get whichever is cheaper.

Ralph Mowery
Guest

Thu Jul 12, 2018 7:45 pm   



In article <6fc3dbef-b41a-4a8f-a3eb-5033c5742824_at_googlegroups.com>,
gherold_at_teachspin.com says...
Quote:
Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac)

I need a replacement. So either a 1 amp 7805
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF

or a LM340
http://www.ti.com/lit/ds/symlink/lm340.pdf

Is there any (practical) difference between the two? (besides the price.)



All of the regulators of that type are the same as far external circuits
go. As long as the voltage and current ratings are the same or greater,
just go with whatever you want.

Just do not interchange the positive ones and negative ones.

Ralph Mowery
Guest

Thu Jul 12, 2018 7:45 pm   



In article <MPG.35b15dce3aab8110989804_at_news.east.earthlink.net>,
rmowery28146_at_earthlink.net says...
Quote:

All of the regulators of that type are the same as far external circuits
go. As long as the voltage and current ratings are the same or greater,
just go with whatever you want.




That should have been the voltage the same and the current same or
greater.

George Herold
Guest

Thu Jul 12, 2018 7:45 pm   



On Thursday, July 12, 2018 at 1:01:55 PM UTC-4, jurb...@gmail.com wrote:
Quote:
Generally, 5 volts is 5 volts. The price shouldn't be a major concern unless you are building a million units. In, ground and out.

At ½ amp you could probably shunt regulate it, a Zener would only dissipate 2.5 watts at no load. Not efficient but probably the cheapest option.

Between the LM340XX-5 and the 7805, I'd get whichever is cheaper.


Thanks, I ordered the cheaper 7805... just wondering.

George H.

Jasen Betts
Guest

Thu Jul 12, 2018 8:45 pm   



On 2018-07-12, George Herold <gherold_at_teachspin.com> wrote:
> Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac)

???

http://www.ti.com/product/lm78m/description

--
ت

Phil Allison
Guest

Fri Jul 13, 2018 3:45 am   



George Herold wrote:
Quote:


Hi all, Simple question.



** So they all say ....


Quote:
Some 1/2 amp LM7805 is obselete (TO-220 pac)


** TO220 pac 7805s are rated at 1.5 amps, long as chip dissipation is not exceeded.

IIRC, obsolete TO202 pac LM341s were 0.5 amp.


Quote:
I need a replacement. So either a 1 amp 7805
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF

or a LM340
http://www.ti.com/lit/ds/symlink/lm340.pdf

Is there any (practical) difference between the two? (besides the price.)


** IME, no. Some devices have both numbers printed on them.

FYI: had to replace a couple of 7815s the other day in a dBx dual 31 band graphic. The regs were full pac versions with NEC brand name.

After warming up a little, both examples shut down completely.



.... Phil

Phil Hobbs
Guest

Fri Jul 13, 2018 9:45 am   



On 07/12/18 12:34, George Herold wrote:
Quote:
Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac)

I need a replacement. So either a 1 amp 7805
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF

or a LM340
http://www.ti.com/lit/ds/symlink/lm340.pdf

Is there any (practical) difference between the two? (besides the price.)

George H.


As long as you're using an electrolytic cap on the output, the two ought
to be equivalent, but they might behave differently with big ceramic or
alpo caps, whose ESR is very low. For instance, the ON Semi TLV431 is
far more prone to oscillate than the TI or Diodes versions.

National used to label its TO220 regulators with both LM7805 and LM340-5
on the same part--I still have some like that.

With old parts like that, it's hard to know if what TI is selling these
days is the old TI part or the old National part or what.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

George Herold
Guest

Fri Jul 13, 2018 3:45 pm   



On Thursday, July 12, 2018 at 3:31:21 PM UTC-4, Jasen Betts wrote:
Quote:
On 2018-07-12, George Herold <gherold_at_teachspin.com> wrote:
Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac)

???

http://www.ti.com/product/lm78m/description

--
ت


Huh, Thanks... I'll order some of those then.
(The Onsemi parts are going away.)

George H.

John Larkin
Guest

Fri Jul 13, 2018 11:45 pm   



On Thu, 12 Jul 2018 13:45:59 -0400, Ralph Mowery
<rmowery28146_at_earthlink.net> wrote:

Quote:
In article <6fc3dbef-b41a-4a8f-a3eb-5033c5742824_at_googlegroups.com>,
gherold_at_teachspin.com says...
Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac)

I need a replacement. So either a 1 amp 7805
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF

or a LM340
http://www.ti.com/lit/ds/symlink/lm340.pdf

Is there any (practical) difference between the two? (besides the price.)



All of the regulators of that type are the same as far external circuits
go. As long as the voltage and current ratings are the same or greater,
just go with whatever you want.


As long as it doesn't oscillate.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

jfeng@my-deja.com
Guest

Fri Jul 13, 2018 11:45 pm   



On Friday, July 13, 2018 at 6:55:20 AM UTC-7, George Herold wrote:
Quote:
Huh, Thanks... I'll order some of those then.
(The Onsemi parts are going away.)

George H.
If your budget can stand it, you might want to consider a switching mode regulator. Some are three-terminal drop-in replacements for the TO-220 devices.


If you are a hardware hacker (literally), you can cannibalize one from a USB car charger. Here in Silicon Valley, Fry's Electronics sometimes sells them for under a dollar. This may not work reliably if your unregulated supply is over 18V, but should work fine if it is 15V or less.

Ralph Phillips
Guest

Sun Jul 22, 2018 12:45 am   



On 7/13/2018 5:34 PM, jfeng_at_my-deja.com wrote:
Quote:
On Friday, July 13, 2018 at 6:55:20 AM UTC-7, George Herold wrote:
Huh, Thanks... I'll order some of those then.
(The Onsemi parts are going away.)

George H.
If your budget can stand it, you might want to consider a switching mode regulator. Some are three-terminal drop-in replacements for the TO-220 devices.

If you are a hardware hacker (literally), you can cannibalize one from a USB car charger. Here in Silicon Valley, Fry's Electronics sometimes sells them for under a dollar. This may not work reliably if your unregulated supply is over 18V, but should work fine if it is 15V or less.


Thankyouthankyouthankyou! I have a function generator that at 12V will
bake the 78L05 TO-92 cased regulator; the switchmode .5A unit should
work a treat in its place so I don't have to have a second PSU just for
it, when working on speedometers for my cars!

RwP

elektroda.net NewsGroups Forum Index - Electronic for beginners - three terminal volt regulator

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