Arcane question, and sort of long, but here goes.... Last night, young son was in the process of adding foglights to his car and asked me for some wire to extend the harness. I wasn't sure what the current draw would be so I grabbed one of the foglight assemblies and connected it to the Eico 1050 battery charger/DC power supply which has been part of my garage tool clutter for nearly 50 years: When I cranked the voltage up to 13, the bulb lit brightly and the ammeter on the Eico read around 9 amps. That seemed sort of high to me so I asked the kid, "How big a fuse is in the harness which came with those lights?" he looked at it and told me it was a 15 amp fuse. 15 amps for TWO 9 amp bulbs? Obviously something was't right, so I got my Simpson 260 and saw that the current drawn by that bulb was really a bit less than 5 amps. Since SWMBO was out getting some "retail therapy" I had some free time, and taking the Eico into my workshop, I opened it up, disconnected the leads to the ammeter and fed it with my bench supply. That verified again that it was reading almost twice the DC current passing through it. By a couple of "cut and trys" I found that about 4 inches of 18 gage solid copper wire shunting the meter made it read correctly enough for "gummint work", so I soldered that wire in and closed the Eico back up. I believe the ammmeter is what I used to know as a "moving iron" type, and IIRC the restoring force was supplied by some kind of permanant magnet field, not by a mechanical spring. Am I right about that? I doubt that Eico installed a defective meter when they built the unit around 1965 (The date marked on the meter.) and I'm guessing that the meter's restoring magnet weakened over 50 years, increasing its sensitivity to nearly double. Anyone have any similar experience with those kind of meters, I'd enjoy learning more, just for the shits and grins of it. Thanks guys, Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "Rudeness is the weak...

Nope. Still a spring. Moving iron vane - The moving iron vane meter operates on the principle of magnetic repulsion between like poles. The measured current flows through a field coil which induces a like magnetic field into a fixed and moving vane causing the moving vane to deflect a pointer in proportion to the current or voltage applied to the coil.

---What did you have in mind, specifically?-- John FieldsProfessional Circuit Designer

---So, even the four-year-old has to dumb it down for you?-- John FieldsProfessional Circuit Designer

DC Ammeter Sensitivity Increased?

Sep 27, 2006 92 Replies

Rate this thread:

John Fields 19 years ago

What did you have in mind, specifically?

Vote

John Fields 19 years ago

So, even the four-year-old has to dumb it down for you?

Vote

Homer J Simpson 19 years ago

Other way around. I need him to translate your demented babblings into something approaching human speech.

Vote

Homer J Simpson 19 years ago

Peg Bundy: "All men are idiots. I married their king".

Vote

John Fields 19 years ago

If it's for _your_ consumption, why bother? A few barks and a bowl of Alpo ought to keep you happy enough...

Vote

Homer J Simpson 19 years ago

Depends not fitting snugly?

Vote

John Fields 19 years ago

Goodbye Homer, you're really not interesting enough to bother with, but thank you for your time.

Vote

Homer J Simpson 19 years ago

We are the champions - my friends And we'll keep on fighting - till the end - We are the champions - We are the champions No time for losers 'Cause we are the champions - of the world -

Vote

Homer J Simpson 19 years ago

Try a higher dose of fibre.

Vote

Homer J Simpson 19 years ago

Yes. On average.

Vote

Jeff Wisnia 19 years ago

Just dropped back in, and in response to your question, the EICO does have a pretty large filter cap in it, though I can't testify to how many of its microfarads may have grown legs and run away over the years.

However, the check I performed against my bench supply, which is definitely well filtered, confirmed the ammeter's calibration error.

I got a few giggles reading some of the interchanges on this thread I started, between "Homer J Simpson" and others.

I'm thinking that some of the participants' alimentary canals may have somehow gotten completely reversed. Medical miricals, to be sure.

Jeff

Jeffry Wisnia (W1BSV + Brass Rat '57 EE) The speed of light is 1.8*10^12 furlongs per fortnight.

Vote

Lostgallifreyan 19 years ago

Jeff Wisnia wrote in news:x9udnZ-VU- M2Cs7YnZ2dnUVZ snipped-for-privacy@conversent.net:

That's been said to be even worse than it sounds. (House...)

Vote

Rich the Newsgroup Wacko 19 years ago

Sounds like a case of optical rectusis - when the optic nerve gets scrambled with the nerve to the bowels.

It gives you a s***ty outlook on life. ;-)

Cheers! Rich

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required