Request help in selecting transformer from Digikey

Nov 20, 2013 10 Replies
D

I apologize if my queries sound silly, so pardon me. The truth is that I have used transformers in my work for a long time, but never bought it myself -- someone else bought the required ones as per my specifications. Now I have to buy some from an online store as Digikey, and am confused, with all details presented to me. I want a 120 V AC -> 9 - 0 - 9 Volt 2 Amp AC transformer. I am also comfortable with two



120 V AC -> 9 - 0 - 9 Volt 1 Amp AC transformers connected in parallel, as I have found this to be a very convenient configuration, both in terms of space occupied by the transformers as well as weight and cost. So I navigated to:
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However, a lot of the presented data confused me.



  1. Who is a reputed manufacturer ?
  2. What exactly is the 'Series' supposed to mean?
  3. Voltage Secondary (Full Load) Now I fully understand what "Parallel 9 V, Series 18 V" means, but why is '18V' listed below ?
  4. Same confusion as for item 3 above holds for Current Output (Max) list - Why for example is 'Parallel 1.02 A, Series 533 mA' listes at the top of the list, but later in the same list is the item '1.06 A' ? Even more confusing are items in the same list : '575 mA, 5 A, 6 A' -- are these some special type of transformers ? Could any electronics guru please help me clear all the confusion ? Thanks in advance for your help.
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P

**The transformer search is dreadful, confuse anyone.

** What it seems you HAVE to do is find the tranny you want at the maker web site and note down all the details.

Then, transfer that data into the Digikey search engine and it will see if they have any.

OTOH, just wade through all the pages of line items until you stumble on it.

IME, a printed catalogue is WAYYYYY easier to use.

Tannys are simply listed by brand, ratings and price.

Find what you want in seconds.

.... Phil

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S

Any of the ones Digikey sell are okay, IMHO. Make sure they have the appropriate safety agency listings for the market you're addressing. There are many, many others who are not okay.

The manufacturer's designation. If it was a car, it would be Buick or Chevy etc. for GM, and something else for Kia, Daihatsu, Land Rover, etc.

Many of the transformers have two isolated secondaries that can be connected in series or in parallel. Many have only one secondary winding. The sorting order in their lists is sort of irrelevant, I think, as long as you realize it exists.

Again, it's some arbitrary sorting thing. That's not too annoying. Their engine gets tempcos completely mixed up.

Click on them (there are only two) and you'll find they're ye olde tube tranformers* with asymmetric (filament and plate) windings. They're also > $150 a pop.

Just flip through a few dozen data sheets and you'll figure it out, and if not, I'm afraid a modest USENET posting isn't going to help much.

*Not to be confused with transformer tubes, which are apparently some kind of drug paraphenalia:
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Best regards, Spehro Pefhany

"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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J

First, let's clear up the purpose of their filter screen, which is to allow you to find what you want a la "20 questions" format. To use the filters, left-click on one of the attributes of the transformer you're looking for, and then left-click on "APPLY FILTERS". For example, if you want a transformer with a single 120V primary, scroll down the "VOLTAGE-PRIMARY box until you see "120V" and then left-click on that followed by a left click on "Apply Filters". That'll get you a list of all of the 120V primary transformers they carry, and you can then further narrow your search by clicking on other attributes in the same way. To select multiple values within a box, hold down 'Ctrl' while selecting values within the box, but only click on "Apply Filters" one box at a time. Your questions: >1. Who is a reputed manufacturer ?
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T

Oh, but Spehro, the web site _clearly states_ that those are for _tobacco_!

Tim Wescott Control system and signal processing consulting www.wescottdesign.com
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A

What's with the flash of a different screen for about a second before the bong page . Here's a sceenprint I caught.

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J

That's the FBI installing the malware to report on your activities.

>
John Devereux
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S

LOL. If it says so on the Internet it must be true.

--sp

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B

So your dad isn't buying them for you anymore?

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G

Dan > The truth is that I have used transformers in my Dan > work for a long time, but never bought it myself -- Dan > someone else bought the required ones as per my Dan > specifications. bloggs > So your dad isn't buying them for you anymore? ROFL

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