Author Options:

how to make a galvanometers from scratch? Answered

EDIT~how to make a galvanometers from scratch? I don't want to make the compass galvanometer or the cheap ones. I want one that will look nice and work great for less than 250 volts.~EDIT does any one have any diagram or schematic/blueprint?


Here are a couple of renderings of the mechanics of a simple moving coil galvanometer. One is a 3D PDF file (click the image to play with it in Acrobat reader) and the other is a hypershot rendering. In the hypershot rendering, you can see a big frame, which is magnetised, and a gold coloured frame - on which you wind a fine coil of wire. The two spiral springs provide the reaction to the force created by the coil when a current flows in it. They ALSO provide the electrical connections to the coil. The usual way of supporting the coil is by sharpened points in jewels, which are non-conducting. Making a fairly big one of these things wouldn't be too hard, and would look spectacular.


Do you want to make big ones ?

What sort of size are you hoping to build ? How long a needle do you want to have ? I wanted to post a PDF file that made things clearer, but for some reason I can't. Steve

can u still post the .pdf though?

i would like to build a 5*5*5 cube or smaller

A galvanometer, in its simplest form, is an electromagnet pulling a spring-loaded piece against the spring's force. (Or two electromagnets in series acting against each other, one fixed and one on the spring.) More current, stronger pull, moving piece moves farther. Mount an indicator to that piece so you can read the result, calibrate it against known current sources, and you've got yourself a meter. Adjusting it for voltage range is a matter of how many wraps are on the coil, how strong the spring is, and what resistance you put in series with the meter. Making it "look nice" is where things get complicated and/or expensive.