Getting old and out of touch

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ShawnR

Member

• Oct 25, 2020

• #1

Hi All

I graduated from college in 1984. I worked for several years in electronics but then diverted to unrelated. I continued to dabble....but knew I was losing ground quickly as electronics advanced.

Today, I was on the bench and the power supply I built several years ago, just a common LM350K based supply, failed. Going to Digikey to get a new regulator, found it to be obsolete unless I buy 50 and then they are $85 plus, each. Searching for TO-3 case regulators, wow....everything I was familiar with seems changed.....

Sooo, what is the norm these days? I found LM338's in a TO220 case, that should work, or go to a 317, reducing the available current to 1 Amp.

LM338T Texas Instruments | Integrated Circuits (ICs) | DigiKey

Order today, ships today. LM338T – Linear Voltage Regulator IC Positive Adjustable 1 Output 5A TO-220-3 from Texas Instruments. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.ca

LM350K STMicroelectronics | Integrated Circuits (ICs) | DigiKey

Order today, ships today. LM350K – Linear Voltage Regulator IC Positive Adjustable 1 Output 3A TO-3 from STMicroelectronics. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.ca

What are hobbyists using for variable power supplies?
Any suggestions?

Feeling old....;-)

 

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Diver300

Well-Known Member

Most Helpful Member

• Oct 25, 2020

• #2

The TO-218 package will fit in the place of the T0-3 package.

I think that the TO-218 was designed to be like that.

I have no idea if there is TO-218 packaged regulator that would work, but you could use a transistor and mount the control electronics elsewhere.

 

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tronitech

Active Member

• Oct 25, 2020

• #3

The LM388 will give you 5A or use the LM317 with bypass transistors for increased current?

 

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ShawnR

Member

• Oct 25, 2020

• #4

tronitech said:

The LM388 will give you 5A or use the LM317 with bypass transistors for increased current?

Click to expand...

You mean LM338? $ 121 ...ouch

LM338K STEEL Texas Instruments | Integrated Circuits (ICs) | DigiKey

Order today, ships today. LM338K STEEL – Linear Voltage Regulator IC Positive Adjustable 1 Output 5A TO-3-2 from Texas Instruments. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.ca

I might have to rework the installation, going with a TO220 case component and a bypass transistor. Something I have thought of for other projects but never actually done.

Thanks
Shawn

 

Last edited: Oct 25, 2020

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Pommie

Well-Known Member

Most Helpful Member

• Oct 25, 2020

• #5

Just had a look at prices. Didn't realize they were so expensive. Over $100 for a TO3 version. Looks like I'm out of touch too.

Mike.

 

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Pommie

Well-Known Member

Most Helpful Member

• Oct 25, 2020

• #6

Just tried ebay and https://www.ebay.com.au/itm/5A-LM33...m4881fb948e:g:43gAAOSwLUxdYO06&frcectupt=true

Mike.

 

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ShawnR

Member

• Oct 25, 2020

• #7

Thanks Mike
I ordered some. I have not looked at ebay for years for stuff. Expected delivery is 1-2 months but I can get by. I am not doing much these days, obviously, anyways.
Cheers,
Shawn

 

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KeepItSimpleStupid

Well-Known Member

Most Helpful Member

• Oct 25, 2020

• #8

You jumped in too fast: https://www.jameco.com/z/LM338K-Maj...ustable-Positive-Voltage-Regulator_23835.html

LM350K prices aren't bad either: https://www.jameco.com/shop/ProductDisplay?catalogId=10001&langId=-1&storeId=10001&productId=23931

Yep, electronics has changed. It's almost like tube to transistors. And because everyone throws away their cell phones every year, we have ROHS or reduction of Hazardous Substances regulations started by the EU.

 

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ShawnR

Member

• Oct 26, 2020

• #9

Thanks KISS

I am in Canada and international shiipping rates would be a lot. If COVID had not caused the borders to be closed, we would normally drive 30 minutes to Minnesota and bring it in, saving customs fees. But, we cannot even cross the border now. Nice to see reasonable prices for those components. If anyone likes them, might be a good time to stock up.
Thank you
Shawn

 

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KeepItSimpleStupid

Well-Known Member

Most Helpful Member

• Oct 26, 2020

• #10

China to US, 0 postage, US to China $20.00 USD. It's like $20.00 everywhere from the US.

 

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sagor1

Active Member

• Oct 26, 2020

• #11

Shawn, be careful of the Chinese LM338K, often they are fake. They put a LM317 inside a metal can and re-label it assuming no one will pull 4A or 5A thru it. Test them carefully, make a circuit with the LM338 on a good heatsink and pull 2 to 3A thru it, see if they survive.
I'm glad I saved all those socketed LM338K pulls I have. If you want to pay postage for a couple free originals (working pulls) from Ontario, contact me off list.

Steve

 

gophert

Well-Known Member

Most Helpful Member

• Oct 26, 2020

• #12

ShawnR
What current and voltage are you looking at? You might want to consider a switch mode power supply (Dc/Dc converter). Much less heat to deal with. Modules are available for very low prices.

 

Beau Schwabe

Active Member

• Oct 26, 2020

• #13

The closest equivalent to the LM350K in the same package is the NTE970 for $18 and change from Digikey. The pin out is the same between the two. Note: if you look at the datasheets one has the bottom view turned 180 from the other... but yes, the pin outs are the same, and the characteristics are the same with an improved output overhead voltage with the NTE970 of 33V versus 25V with the LM350K. Input voltages are the same ( 35V) and current is the same (3A)

364 in stock as of 10-26-2020

NTE970 NTE Electronics, Inc | Integrated Circuits (ICs) | DigiKey Marketplace

Order today, ships today. NTE970 – Linear Voltage Regulator IC Positive Adjustable 1 Output 3A TO-3 from NTE Electronics, Inc. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.com

 

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ShawnR

Member

• Oct 28, 2020

• #14

Thanks everyone. Since I have the ebay ones ordered, I will wait to see what happens. It is just the variable side of my multi output power supply. I can get by with the fixed 5 and 12 v outputs.

Regards
Shawn

 

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ShawnR

Member

• Mar 22, 2021

• #15

Well, this thread dates back to October and I still have not received my order from the ebay seller. Projected delivery was into January...it was so far away, I did not even pay attention but here it is March and still, nothing. I contacted them and their answer was that they mailed it to the address supplied....of course.....oh well I figured it was a gamble of $7ish.

On to plan B. I have not needed the power supply so have not missed it.

 

MacIntoshCZ

Active Member

• Mar 23, 2021

• #16

ShawnR said:

Well, this thread dates back to October and I still have not received my order from the ebay seller. Projected delivery was into January...it was so far away, I did not even pay attention but here it is March and still, nothing. I contacted them and their answer was that they mailed it to the address supplied....of course.....oh well I figured it was a gamble of $7ish.

On to plan B. I have not needed the power supply so have not missed it.

Click to expand...

It happens sometimes. Like 1 from 30 orders is lost in my case.

 

Musicmanager

Well-Known Member

• Mar 23, 2021

• #17

Is there some sort of restriction on posting electronic components in Canada then ?

Since I've just purchased a few LM338's I was curious of the problem.
I paid £11 sterling for a pack of 5, and Royal Mail's website says I can post them to Canada, tracked & signed for for £6.85 .. .. ..

In fact Shawn, if that would help, I can do exactly that ?

MM

 

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sagor1

Active Member

• Mar 23, 2021

• #18

I'm in Canada and offered a couple clean LM338K pulls for free back in October, if he wants to pay the postage. Since they are bulky (not envelope size), shipping will have to be "small package", which usually runs around $15 CAD.