Tweakers' Asylum

Posted by Christopher Witmer (A) on April 27, 2007 at 17:28:42

Here in Tokyo I don't have a ready source of Hammond Series 193 chokes (that I know of). There are a few inexpensive candidate chokes being sold on a local internet auction site that I’d like to ask about. First, the one shown below weighs 7kg (15 lbs+), and the only information I have about it is what is visible in the photo. My primary concern is that I have no idea what the maximum operating voltage is. Obviously, one way to find out if it works is to plug it in and see whether it results in a fire. However, it occurs to me that perhaps there might be a more intelligent approach to take before I go stuffing "mystery meat" into my AC line's digestive tract.

ANY ADVICE WOULD BE GREATLY APPRECIATED. If I’m just asking for trouble by messing with this, I’ll pass. The price is about US$15.

Another item (http://img292.imageshack.us/img292/7361/kamasho01img600x4501173zy5.jpg) is a 9kg (20 lb) "AC Reactor" that was made in 2002 and has never been used. This is a three-phase device built around a nice laminated steel core. (I'm assuming that there are ways of using three-phase devices on single-phase lines.) This is marked as follows --
Insulation: B
Hz: 50/60
Line: 400/440V, 200/220V
A: 140
mH: 0.049
The price is about US$26

If either of these devices might be worth messing with for AC power line conditioning and/or noise filtering, I would greatly appreciate some advice on how to approach.

Thanks!

Chris

• ***BE VERY CAREFUL*** - Al Sekela 21:48:41 04/27/07 (2)
  In Reply to: In lieu of a Hammond Series 193 choke . . . how to test this safely? posted by Christopher Witmer on April 27, 2007 at 17:28:42:

  The Hammond choke has a nominal inductance of 5 henrys. The unit in your photo is rated as 8 millihenrys. This is 0.008 henry. The impedance at 60 Hz is given by the formula

  Z = j*omega*L,

  where j is the square-root of -1; omega is 2 times Pi times the frequency in Hz, and L is the inductance in henrys. The result for 0.008 henry is 3.0 ohms. The inductor would draw 40 amps of reactive current if plugged in to a 120 volt, 60 Hz AC circuit! Compare this to the 64 milliamperes drawn by a 5 henry choke: that is 0.064 amperes.

  The name plate indicates the choke is designed for 8.5 amps DC. I don't know what it was used for, but it is not suitable as a replacement for the Hammond choke.

  The AC reactor has even less inductance (0.000049 henry) and is rated for much more current. It would have been used in a large industrial power application. I don't think it is useful for domestic AC filtering.
  
  

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  • Consider the idea scrapped -- I'll use the right tool for the job - Christopher Witmer 23:56:17 04/27/07 (1)
    In Reply to: ***BE VERY CAREFUL*** posted by Al Sekela on April 27, 2007 at 21:48:41:

    The other alternative readily available to me (which is being discussed a few threads back), of using one side of a transformer, is what I'll pursue until I can obtain a proper Hammond choke or a true equivalent.

    Thanks for helping me stay out of the Darwin Awards this week.
    
    

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    • Re: Akihabara, main drag - grinagog 00:11:57 04/28/07 (0)
      In Reply to: Consider the idea scrapped -- I'll use the right tool for the job posted by Christopher Witmer on April 27, 2007 at 23:56:17:

      Chris;
      there's a store on the main street in Akihabara that sells nothing but transformers + chokes ( I think they claim to have 7000+ types in stock ) and pretty reasonably priced, if you're in Tokyo check 'em out over Golden week

      Grins
      
      

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