General > Buy/Sell/Wanted

I sourced 100 LT3080 T0-220 Parts, will list on ebay.

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minime72706:
NOTE: I'VE NOTICED THAT THERE IS A UK SELLER OF THESE; I'D PROBABLY BE MORE CONVENIENT FOR THOSE IN USA/CANADA.

Hey y'all!

I've been thinking about building an adjustable, CV/CC, computer-controlled, DC power supply for a long time and I've been a viewer of EEVblog off and on. I came across the power supply series last month and took an interest in it. I was most pleased to be introduced to a better alternative to the LM317, the LT3080. I sourced 100 parts in the TO-220 package directly from Linear Technologies because the price break at 100 and shipping costs made it impractical to buy something like only 10. They seem somewhat hard to get and surprisingly there's no one on eBay selling them, so I bought way more than I needed to justify (in my mind) buying them at all. I had hoped that some people would be happy to have a different route to purchase them as well, so hopefully they don't sit around!

I'll likely sell the LT3080 in quantities of five (5) for something like $30 shipped. They're $3.14 a pop in quantities under 100 and shipping (for me in MA, USA) was about $11, so it seems fairly reasonable to me. I may drop the price and then charge actual postage to make it a bit more fair, but that's somewhat of a pain for me. After seeing Dave's video about anti-static and static-dissipative bags, I'll certainly use real 3M metal-in anti-static bags! I've not received the parts yet as I've only ordered them a few days ago (and they appear to be back-ordered); I'm posting preemptively to gauge interest! My eBay seller name is the same as my username on this forum, but again, you'll find nothing right now! I'll update when I receive parts and are ready to ship. I'll probably keep 20-25 for myself and put the rest up for sale.

Thanks!

free_electron:
Please do explain why you think the LT3080 is better than an LM317....

minime72706:
Why don't you watch his video series on his power supply design? This is not MY idea. (when searching the episode list, beware, he changes the title 3 times in the series of like 8-9 episodes)

Since it uses a current source and resistor as a reference, one can force a voltage into the control pin and achieve output voltages closely approaching 0V.
With the LM317, a 1.25V voltage reference is used and any voltage you put on the ADJ pin is in SERIES with that 1.25V. In order to operate down close to 0V you would normally need a negative voltage.
The LT3080 also boasts a much lower drop-out voltage.
Furthermore, it is rather simple to safely put the LT3080 in parallel with more of its kind to get a higher output current. With some resistive ballasting you can design your circuit so they share the power load rather evenly.

You can generally design a circuit using an LM317 to do what you want, but the LT3080 simplifies things in many ways. I might even be less noisy and more stable, but it's not important enough for me to compare datasheets.

The use of an ellipse (....) signifies impatience; there's no need for that.

free_electron:
MY question was based on this :

--- Quote ---I've been thinking about building an adjustable, CV/CC, computer-controlled, DC power supply for a long time
--- End quote ---

here is the problems with the LT3080 for that given setup:

1) no current control... you'll have to create another regulation loop that will have to fight the LT3080 regulation

2) max 1.1 ampere.. the LM317 does 1.5

3) low drop.. who cares.. a lab power supply burns off 90% of the energy anyway .. you start with 20 or 30 volt at the input to make 5 volt at the ouptut. low-drop is a non issue in this case

4) controllable to 0 volt. so is an lm317 if you use a negative reference voltage.

5) Neither the lt3080 or the lm317 are advisable for lab power supply usage. Don't get me wrong, they are great regulators , but they are intended to be put in a system where a set of resistors aligns them to make a specific voltage and the STAY there for the rest of their useful life. You do not slap a potentiometer on them and build a 'lab power supply with them
they are no where near robust enough , too many limitations , no protection , no controllable current limit no nothing. They are intended for a finished product. not a lab instrument.

and then there is this whole 'computer control' stuff. we are going to spend 50$ in parts to slap on a fancy display and computer control but it is too cumbersome and 'expensive' to buld a decent regulator section. ( which would cost like 10$ ). Of course hammering software on a pic and pc is easier than making a good analog control loop. This is my gripe with these kinds of projects.
Note : i am NOT attacking you. It's just that the internet is full of total crap designs made by people who have an affliction for writing code but have no clue how to properly use an opamp and transistor. The end result is always pure garbage. If you are really serious about making a good DC power supply , that is computer controllable , start with building a solid regulator system and provide a properly protected power section. and THEN slap on a pic if you want to.

BravoV:

--- Quote from: free_electron on July 03, 2012, 05:26:11 pm ---here is the problems with the LT3080 for that given setup .... <snip>...

... <snip>...

5) Neither the lt3080 or the lm317 are advisable for lab power supply usage.

.... <snip>...

Note : i am NOT attacking you. It's just that the internet is full of total crap designs made by people who have an affliction for writing code but have no clue how to properly use an opamp and transistor. The end result is always pure garbage. If you are really serious about making a good DC power supply , that is computer controllable , start with building a solid regulator system and provide a properly protected power section. and THEN slap on a pic if you want to.

--- End quote ---

Assuming you've watched those videos, I guess you're politely saying that Dave's design is also total crap since he is using LT3080 for his upcoming psu that he is going to sell.

Just correct me if I'm wrong.  ;)

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