Conway Galvanometer Info?

[mstoer]

I received this galvanometer made by Conway Electronic Enterprises from my daughter as a birthday gift.   She picked it up at the ReStore  and while it came in a box, there are no markings as to it's manufacture date or model or anything official.   There is just handwritten on the box "Galvo" in pen and "A1768" in marker.

Guessing it might have a +/- 50uA range, I tested it and compared it to my Rigol bench meter.   It seems to work well and here is one photo below of a test at 24.03 uA (measured on the Rigol).

Does anyone have any idea as to manufacturing date?  Also, would the model number be 6009 and the serial A1768?  I just wanted to see if there is any history I can add to this before I put it up on the shelf.

Marcell

[zlymex]

Great stuff. If it is a galvanometer, the internal resistance must be very low.

[Gyro]

A nice thoughtful gift. 

From the style, I would think that September 1960 (as in 6009), would be quite realistic.

It would have been used as a null detector for a Wheatstone bridge or probably potentiometer setup, hence to momentary push button to avoid pulling current for longer than necessary.

[mstoer]

I opened it up looking for more info.   I noticed that the range is internally selectable (set to 0.05mA) at the moment.  I also saw that the wire to what I assume is a varistor (marked VR-60 with Sanken logo) was disconnected.   It measures shorted (0.2ohms), so I'm guessing it blew at some time and then someone de-soldered the lead to continue to use it.   Been trying to google what specs the VR-60 might have had if I want to replace it. Can't seem to find it anywhere so far.

Marcell

[joeqsmith]

You had to pull the cover and re-strap it to change the range?   

With the second hole in the board, I wonder if the VR-60 was a "custom" mod for some range they were trying to get.   Maybe you could find a KOA 2K2 5W and install it back into the board.  Remove the thin red wire.  If you wanted to make it work again.    I would just leave it the way it was and select one of the other ranges if you wanted to try and play with it.     

[mstoer]

I didn't change anything so far.  I lifted the board and it looks to me as if the 1.2k resistor was always there.  Below the board there is no indication anything was altered or de-soldered.  It works fine as is in with a 50uA full scale range.  I am assuming the VR-60 was for over-voltage protection.

The case has several other threaded inserts, likely for mounting other boards for different products.  It could be this board had multiple uses as well.

[lowimpedance]

Interesting 'old timer'!, I wonder if VR-60 was a diode? (I have seen similar vintage packaging to this in old gear). Just a thought !.

[Peter pierre]

Hi,
I have just purchased exactly the same model as you have shown pictures of. I know nothing about these and I would greatly appreciate if you could take the time to answer a couple of questions as you seem to know a lot more about this galvanometer then I do.

1. Can I safely connect an ordinary battery (AAA, AA, C,D, 9volt, 3 v lithium, etc. to this device? The reason I ask is from the little bit of information I have gathered is that it seems that if the current is too strong there is something that could burn out. Is there a limit of time I can activate the galvanometer that makes it more liable to burn it out? Could I connect a car battery to it without any danger? Does it always require a resistor between source of current and galvanometer? If I'm correct this is only good for DC current and not AC current?
2. What do the numbers on the dial refer to: volts, amperes, ohms?

Thank you for taking the time to answer these questions, you can answer me directly at sennevillepete@hotmail.com

Pierre

[TimFox]

Do not connect a battery (even a small one) directly to a sensitive current meter!
To measure the current, apply the voltage through a (large) resistor.  9 V and  50 uA imply 180 kohm.
You could easily smoke the coil in the meter.
As the original poster demonstrated, the meter shows microamps up to +/- 50.
Usually, the term “galvanometer” implies a meter with zero at the center.

[Peter pierre]

Hi Tim,
Thank you so much for your reply, from what you have informed me of I have no use for this machine, it is way beyond me, I bought it brand new sealed in package out of curiosity, thinking I could easily use it as a voltmeter or ammeter. I guess not! I will look to pass it on, if you know of anybody who might be interested in buying it off me for a reasonable price they can contact me at my email address: sennevillepete@hotmail.com . Once again thank you for your reply, you prevented me from ruining a brand new machine that might be of use to someone else. Cheers