Simple Capacitance Tester

[Hammonds]

Hi have come across this Simple Capacitance Tester made by H.W.Sullivan of London.

Has anyone seen one before, and does anyone know how it works, and the significance of all the connections, especially the springy ones on the back.

It looks as if it belongs in a museum, but does it have any value and is it worth putting it up for sale in the appropriate part of the Forum?

Many thanks

Cheers

Dave

[WME_bill]

Simple Capacitance Tester.
Looks much more like a variable calibrated standard capacitor to me.
What makes you say it is a Tester. Does it say so somewhere?
Have you a picture of the vanes which move with the main knob.
Is that a fixed capacitor, two plates with mica in between, in picture 3. That could be switched in for the higher ranges.
All most intriguing. wme_bill

[Hammonds]

Here are a couple more photos for clarification.

There does seem to be a fixed? mica (sandwiched between two thick aluminium plates) capacitor attached firmly to the base.

Dave

[Andrewausfa]

Dave,

I think the spring clips must be to hold a battery cell of some description. The rest of it is a bridge, 'X' terminals connect to your unknown value capacitor that you want to measure. 'Tel' is for a pair of headphones for indication of bridge balance. A and B buttons look like range switching. No idea what the large knob is top right or the Buzzer switch.

There was a good article about H.W. Sullivan in The Bulletin a few years ago.

Andrew

[Restoration73]

A reference variable capacitor (which Sullivan also made) will only have two terminals,
well maybe three if there is a connection to a metal box or screen. This appears to
be a simple bridge, with the unknown cap connected to X and high impedance phones
connected to Tel. The AC voltage could be generated by a buzzer, possibly with a
step up voltage winding, and an internal battery would connect possibly to those
two springs. Try a 3V or 4.5V battery and press the button Buzzer.

[Refugee]

It looks very simple.
Perhaps it is a bridge driven by a buzzer and the value would most likely be given at the point where the audio in the phones comes to a minimum.
I have got a posh one with a magic eye on it.

[ms660]

Similar one here:

http://www.radiomuseum.org/r/sulliva..._test_set.html

Are there any resistors in there?

Lawrence.

[Phil G4SPZ]

We have a far less professional-looking bit of vintage kit in the Black Country Living Museum. It measures resistance as well as capacitance, and is remarkably accurate. It is indeed based on a bridge circuit with a buzzer running off a 2-volt accumulator generating an AC waveform at an audio frequency.

[Gridiron]

I've got one of these in poor condition which I acquired for the buzzer which fitted an early Townsend Wavemeter, most I've seen have an Ivorine scale which shrinks and distorts with age, making the scale useless. Yours has a scale made of different material which looks OK. They seem have made £10 to £20 at BVWS auctions.
Mike.

[Hammonds]

Hi Folks

Thanks for all the info.

Connecting a 5 volt power supply to the two metal connectors does the trick.

Pulling the buzzer knob out, there's a high pitched whine. I'm amazed it still works - H.W. Sullivan certainly knew how to make things last. Exploring HWS's history makes interesting reading.

All I need now is a pair of high impedance headphones or some sort of amplifier and speaker.

I'll keep you posted.

Dave

[Hammonds]

Hi again

I used my trusty Fluke to check the capacitance of a 0.1 uF cap and then used the Fluke instead of headphones or amplifier.

Adjusted the pointer on the shaft to get the right reading, so now all is well.

Thanks to everyone who has helped in any way.

All it needs now is a new home.

Best regards

Dave

[Hammonds]

Hi good people

I've offered this Simple Capacitance Test Set to the Science Museum but they have declined, saying that "although my example is in good condition, they already have one and their current policy is to only have one example of each item"

So if any one knows of a local museum which would like it, I would willingly give it away.
https://www.vintage-radio.net/forum/...d.php?t=136957

Best regards

Dave