Poll

Are you buying the powersupply kit ?

Yes
No
Perhaps

Author Topic: Do you want to buy the powersupply kit ?  (Read 45142 times)

0 Members and 1 Guest are viewing this topic.

Offline Blue

  • Regular Contributor
  • *
  • Posts: 55
  • Country: nl
  • Fighting for peace is like fucking for virginity
Re: Do you want to buy the powersupply kit ?
« Reply #50 on: January 10, 2012, 09:50:56 pm »
Spikee,

have a look here: http://www.douane.nl/particulier/internetaankopen/internetaankopen-03.html#P140_8194

Not included is the extra you have to pay someone (commercial company) that is doing all the maths and sending you the invoice.  After you paid, they will release the package. This hassle will cost you an additional two weeks for delivery.

From the above mentioned website: Uiteindelijk kost dat maatpak u € 313,21 plus de eventuele inklarings- en afhandelingskosten van het post- of koeriersbedrijf.
« Last Edit: January 10, 2012, 09:57:08 pm by Blue »
 

Offline rr100

  • Frequent Contributor
  • **
  • Posts: 337
Re: AW: Do you want to buy the powersupply kit ?
« Reply #51 on: January 11, 2012, 03:36:06 pm »
In Europe the Vat =18-21 %.
It is in fact up to (and including) 27% (and I'm talking EU only, don't know much about VAT in non-EU european countries).
If you hit the customs (as in above the threshold around 100 euro or whatever it is) as mentioned the charges can be really painfull. And I think VAT/customs are applied to the whole value (including postage). I don't know if you pay VAT on the customs charges or vice-versa (I wouldn't be surprised).
The postage itself is usually in the tens of dollars for anything other than padded envelopes, especially if you want any tracking or insurance (minimal one, 100-200$). And again as mentioned if you use the DHL and the like they might charge you again some tenners to do the customs for you.
Add the 1-3% (or sometimes more) for the transaction itself (either straight credit card charges or paypal "biased" exchange rate) and it's not unusual for the 100$ item to leave you without 150 EUR. That is while staying under the threshold where real "customs" charges would be applied. Not funny.
 

Offline Bloch

  • Supporter
  • ****
  • Posts: 440
  • Country: dk
Re: Do you want to buy the powersupply kit ?
« Reply #52 on: January 11, 2012, 06:40:10 pm »
For Denmark (EU) Text from http://www.toldpriser.dk/toldregler


When you buy a product in a country outside the EU, which has a value above 80 kr, you must pay VAT, duty and customs of the goods.


The rates at which a shipment must clear customs are as follows:
Less than 80 kr: You need not pay customs duties, VAT or customs clearance fee
80 to 1,150 kr: You must pay VAT and customs fee
Over 1,150 kr: You must pay VAT, customs and clearance fees


Let's say you buy some clothes in the U.S. at a price of 1,500 kr,
You pay 50 kroner to get the product sent home to Denmark and the duty forexample. jeans and jeans is 12%.
Calculation  therefore looks like this:Duty is 12% of product value and postage ie. (1,500 kr + 50 kr) * 0.12 = 186kr

The VAT is 25% of product value + postage + customs, ie. (1500 + 50 + 186) * 0.25 = 434 kr

Add to that clearance fee of DKK 160

You will then be charged 780 kr from Tax and Post Denmark to get it to Denmark.

When the clothes are at home at your doorstep, you have therefore paid:
Price of goods: 1500 kr
Shipping: 50 kr
Customs: 186 kr
VAT: 434 kr
For customs: 160 kr
Total: 2325 kr
 

Offline Stephen Hill

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
  • M3VXY
Re: Do you want to buy the powersupply kit ?
« Reply #53 on: January 11, 2012, 09:48:58 pm »
... back to the original topic.

I unfortunately won't be buying the kit because I'm designing my own microcontroller controlled power supply and incorporating some of the idea and techniques that Dave has presented in his design.

My design will be using an LM317 instead of the LT3080 because no one seems to sell them in the UK. I've also kept the current limiting opamp instead of the custom current IC.

I'm learning so much while following Dave's videos, so even though I won't be buying the kit, I'll be making sure a donation is sent his way.

Cheers
Stephen

PS: @Dave: After reading a PDF on the web... What is the burden voltage of your Fluke 87? No looking it up!
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 29250
  • Country: au
    • EEVblog
Re: Do you want to buy the powersupply kit ?
« Reply #54 on: January 11, 2012, 10:07:44 pm »
PS: @Dave: After reading a PDF on the web... What is the burden voltage of your Fluke 87? No looking it up!

Considering that would be likely written by me :->, I should be able to get this right from memory - 1.8mV/mA?

Dave.
 

Offline Stephen Hill

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
  • M3VXY
Re: Do you want to buy the powersupply kit ?
« Reply #55 on: January 11, 2012, 10:29:15 pm »
PS: @Dave: After reading a PDF on the web... What is the burden voltage of your Fluke 87? No looking it up!

Considering that would be likely written by me :->, I should be able to get this right from memory - 1.8mV/mA?

Dave.

Correct :)

Now don't ask what mine is. I have no idea!

Cheers
Ste
 

Offline Tooms

  • Supporter
  • ****
  • Posts: 91
  • Country: dk
Re: Do you want to buy the powersupply kit ?
« Reply #56 on: January 11, 2012, 10:39:57 pm »

My design will be using an LM317 instead of the LT3080 because no one seems to sell them in the UK. I've also kept the current limiting opamp instead of the custom current IC.

Ebay has them

 

Offline Stephen Hill

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
  • M3VXY
Re: Do you want to buy the powersupply kit ?
« Reply #57 on: January 11, 2012, 10:50:41 pm »

My design will be using an LM317 instead of the LT3080 because no one seems to sell them in the UK. I've also kept the current limiting opamp instead of the custom current IC.

Ebay has them

True. But I'm not willing to part £7-14 for a voltage regulator. Perhaps we could organise a group buy. Ordering 25 from UK Farnell would cost £4.37 each plus a little for postage. I would still consider this pricey but much better than ebay.

Cheers
Stephen
 

Offline IanB

  • Super Contributor
  • ***
  • Posts: 9487
  • Country: us
Re: Do you want to buy the powersupply kit ?
« Reply #58 on: January 11, 2012, 10:56:08 pm »
My design will be using an LM317 instead of the LT3080 because no one seems to sell them in the UK.

Farnell appears to have them in the TO-220-5 package at £4.17 each. Is there a hidden catch I am missing?
I'm not an EE--what am I doing here?
 

Offline Stephen Hill

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
  • M3VXY
Re: Do you want to buy the powersupply kit ?
« Reply #59 on: January 11, 2012, 11:00:08 pm »
My design will be using an LM317 instead of the LT3080 because no one seems to sell them in the UK.

Farnell appears to have them in the TO-220-5 package at £4.17 each. Is there a hidden catch I am missing?

"US Stock items that have a service charge indicated are coming from our Newark warehouse. The service charge will be £15.95 per order, in lieu of a freight charge for Newark items."

So this is why I would suggest a group buy. Order we could put pressure to Farnell to stock them locally in the UK.
 

Offline IanB

  • Super Contributor
  • ***
  • Posts: 9487
  • Country: us
Re: Do you want to buy the powersupply kit ?
« Reply #60 on: January 11, 2012, 11:16:26 pm »
"US Stock items that have a service charge indicated are coming from our Newark warehouse. The service charge will be £15.95 per order, in lieu of a freight charge for Newark items."

So this is why I would suggest a group buy. Order we could put pressure to Farnell to stock them locally in the UK.

Ah, that's a bit of a gotcha. But it looks like the SOT-223 package is in stock locally and it's cheaper too. Wouldn't that be an acceptable substitution?
I'm not an EE--what am I doing here?
 

Offline im_a_human

  • Regular Contributor
  • *
  • Posts: 70
  • Country: gb
Re: Do you want to buy the powersupply kit ?
« Reply #61 on: January 11, 2012, 11:58:59 pm »
I would like another powersupply especialy for precision work.
 

Offline Stephen Hill

  • Regular Contributor
  • *
  • Posts: 178
  • Country: gb
  • M3VXY
Re: Do you want to buy the powersupply kit ?
« Reply #62 on: January 12, 2012, 12:02:03 am »
"US Stock items that have a service charge indicated are coming from our Newark warehouse. The service charge will be £15.95 per order, in lieu of a freight charge for Newark items."

So this is why I would suggest a group buy. Order we could put pressure to Farnell to stock them locally in the UK.

Ah, that's a bit of a gotcha. But it looks like the SOT-223 package is in stock locally and it's cheaper too. Wouldn't that be an acceptable substitution?

Such a small package would very hard, if not impossible to keep cool. See the datasheet for an example.
 

Offline IanB

  • Super Contributor
  • ***
  • Posts: 9487
  • Country: us
Re: Do you want to buy the powersupply kit ?
« Reply #63 on: January 12, 2012, 12:30:56 am »
Such a small package would very hard, if not impossible to keep cool. See the datasheet for an example.

Hmm. The datasheet gives a thermal resistance of 3 K/W between junction and case for the TO-220 package, but it does not give an equivalent number between junction and tab for the SOT-223 package. That makes like-for-like comparisons rather difficult. I had thought perhaps to solder the SOT-223 package to a copper heat sink by its tab and use flying leads to the pins. In other words to to turn the SMT part into a make-shift through hole part.  For home build construction you don't always have to mount devices in the manner intended for automated production. Would be hard of course with aluminium heat sinks.

I'm not sure how feasible it might be...
I'm not an EE--what am I doing here?
 

Offline amspire

  • Super Contributor
  • ***
  • Posts: 3638
  • Country: au
Re: Do you want to buy the powersupply kit ?
« Reply #64 on: January 12, 2012, 02:12:12 am »
Such a small package would very hard, if not impossible to keep cool. See the datasheet for an example.

Hmm. The datasheet gives a thermal resistance of 3 K/W between junction and case for the TO-220 package, but it does not give an equivalent number between junction and tab for the SOT-223 package. That makes like-for-like comparisons rather difficult. I had thought perhaps to solder the SOT-223 package to a copper heat sink by its tab and use flying leads to the pins. In other words to to turn the SMT part into a make-shift through hole part.  For home build construction you don't always have to mount devices in the manner intended for automated production. Would be hard of course with aluminium heat sinks.

I'm not sure how feasible it might be...

The datasheet has all the thermal specs for the different packages on the second page of the data sheet. The SOT package is 15 DegC/W. The two surface mount packages with 3 DegC/W are the 8 lead plastic DFN package and the 5 lead DD-PAK package. I would think the DD-PAK has the bigger heatsink tab area, so it will probably make the best thermal connection to the heatsink.

Richard.
 

Offline IanB

  • Super Contributor
  • ***
  • Posts: 9487
  • Country: us
Re: Do you want to buy the powersupply kit ?
« Reply #65 on: January 12, 2012, 04:46:29 am »
The datasheet has all the thermal specs for the different packages on the second page of the data sheet. The SOT package is 15 DegC/W. The two surface mount packages with 3 DegC/W are the 8 lead plastic DFN package and the 5 lead DD-PAK package. I would think the DD-PAK has the bigger heatsink tab area, so it will probably make the best thermal connection to the heatsink.

Well thank you, I didn't spot that.

Unfortunately, the DD-PAK is also US stock, so it still commands a nasty surcharge. The DFN package is stocked in the UK, but that thing would be a pain to solder to a big heat sink. As an ex-UK resident, I sometimes think it would be great to have one foot on both sides of the Atlantic and live in both places at once. Sadly there aren't too many jobs that permit that, and it would make filing tax returns horribly complicated.
I'm not an EE--what am I doing here?
 

Offline thilo

  • Regular Contributor
  • *
  • Posts: 51
Re: Do you want to buy the powersupply kit ?
« Reply #66 on: January 12, 2012, 02:05:44 pm »
Hey Dave, do you have a ball-park figure for the kit's price yet?

And would you consider to provide the kit in a surplus version? I'd like an extra unit of the LT3080 and the SMD components, because I'm sure I'll want to use the 3080 in a future project and I haven't a lot of experience in SMD soldering. I suppose others want spare units of other parts. And I really don't want to burden you with packaging each kit individually. So maybe we could compromise on a surplus unit where all the ICs are included twice (or thrice)?

Thilo.
 

Offline plunger

  • Contributor
  • Posts: 35
  • Country: us
Re: Do you want to buy the powersupply kit ?
« Reply #67 on: January 12, 2012, 05:41:23 pm »
What kind of time frame might this happen? I'm in need of my first powersupply.
 

Offline Chet T16

  • Frequent Contributor
  • **
  • Posts: 522
  • Country: ie
    • Retro-Renault
Re: Do you want to buy the powersupply kit ?
« Reply #68 on: January 12, 2012, 06:35:36 pm »
I think as a first power supply something in the generic 0-30v 0-5A range would be better suited. Daves supply is more niche with its lower voltage/current output but far greater precision. Both supplies definitely have their place and i'll be looking to get one of Daves
Chet
Paid Electron Wrestler
 

Offline IanB

  • Super Contributor
  • ***
  • Posts: 9487
  • Country: us
Re: Do you want to buy the powersupply kit ?
« Reply #69 on: January 12, 2012, 06:54:02 pm »
I think as a first power supply something in the generic 0-30v 0-5A range would be better suited.

But why? What is the basic electronics experimenter going to do with such a beast?

For every electronics need I have encountered, 0-12 V and 0-1 A has been more than sufficient.

If I have needed more power than that it has been for non-electronics applications like driving lamps or motors. And for that a linear supply is scarcely necessary. A cheaper switch mode supply does just fine.
I'm not an EE--what am I doing here?
 

Offline benemorius

  • Regular Contributor
  • *
  • Posts: 173
Re: Do you want to buy the powersupply kit ?
« Reply #70 on: January 12, 2012, 07:57:02 pm »
I think as a first power supply something in the generic 0-30v 0-5A range would be better suited.

But why? What is the basic electronics experimenter going to do with such a beast?

For every electronics need I have encountered, 0-12 V and 0-1 A has been more than sufficient.

If I have needed more power than that it has been for non-electronics applications like driving lamps or motors. And for that a linear supply is scarcely necessary. A cheaper switch mode supply does just fine.

The thing about a first power supply is that a beginner may not know what the requirements are going to be in the near future. I needed about 15 volts from the first power supply I ever bought. That was for automotive use, which is probably not uncommon at all. If I bought my first one now it would need to do 20+ for a PLC I'm working with. Those are the only two >10V needs I've had that I can think of off the top of my head so I'll certainly agree that 95% of the time or more you won't need that much voltage, but there's still that 5% or less to worry about and this is one case where "almost enough" is no good at all. A typical beginner isn't going to want to have to get two power supplies, so it really seems like a valid goal to try to make the first one as versatile as is reasonably possible.
 

alm

  • Guest
Re: Do you want to buy the powersupply kit ?
« Reply #71 on: January 12, 2012, 08:14:35 pm »
A typical beginner isn't going to want to have to get two power supplies, so it really seems like a valid goal to try to make the first one as versatile as is reasonably possible.
It's quite common to need multiple power supplies, so I'm not sure if I agree with your assertion. You may need multiple power supply to provide 12/24V for motors and 5V for logic for example, or 5V and 3.3V logic, or to provide symmetrical power supplies for op-amps. Might as well get two and put them in series/parallel for higher voltage/current.
 

Offline Chet T16

  • Frequent Contributor
  • **
  • Posts: 522
  • Country: ie
    • Retro-Renault
Re: Do you want to buy the powersupply kit ?
« Reply #72 on: January 12, 2012, 08:28:18 pm »
I think as a first power supply something in the generic 0-30v 0-5A range would be better suited.

But why? What is the basic electronics experimenter going to do with such a beast?

For every electronics need I have encountered, 0-12 V and 0-1 A has been more than sufficient.

If I have needed more power than that it has been for non-electronics applications like driving lamps or motors. And for that a linear supply is scarcely necessary. A cheaper switch mode supply does just fine.

I wasn't suggesting 30V and 5A were needed but most of the bench power supplies out there on ebay etc fall in that category.

Obviously different people will have different needs but i wouldn't recommend a supply with less than 12V for a first supply which is what Daves will be
Chet
Paid Electron Wrestler
 

Offline benemorius

  • Regular Contributor
  • *
  • Posts: 173
Re: Do you want to buy the powersupply kit ?
« Reply #73 on: January 12, 2012, 08:33:37 pm »
A typical beginner isn't going to want to have to get two power supplies, so it really seems like a valid goal to try to make the first one as versatile as is reasonably possible.
It's quite common to need multiple power supplies, so I'm not sure if I agree with your assertion. You may need multiple power supply to provide 12/24V for motors and 5V for logic for example, or 5V and 3.3V logic, or to provide symmetrical power supplies for op-amps. Might as well get two and put them in series/parallel for higher voltage/current.

Yes, absolutely. No argument there at all. Even two is not enough, eventually. I only meant to suggest that someone who is just getting their feet wet might find one multipurpose supply more affordable than two supplies with narrower ranges.
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 29250
  • Country: au
    • EEVblog
Re: Do you want to buy the powersupply kit ?
« Reply #74 on: January 12, 2012, 08:46:03 pm »
Obviously different people will have different needs but i wouldn't recommend a supply with less than 12V for a first supply which is what Daves will be

It's not designed as a first supply.
There are countless 30V/3A supplies on ebay for less than what this kit will cost.
This is different, it is not trying to compete, I designed it for a specific reason you have not really seen yet.

Dave.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf