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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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4th Apr 2017, 9:24 pm | #1 |
Heptode
Join Date: Feb 2011
Location: Southampton, Hampshire, UK.
Posts: 574
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Simple Capacitance Tester
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 Last edited by Hammonds; 4th Apr 2017 at 9:26 pm. Reason: typos |
4th Apr 2017, 9:59 pm | #2 |
Octode
Join Date: Oct 2007
Location: Exeter, Devon, UK.
Posts: 1,554
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Re: Simple Capacitance Tester
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 |
4th Apr 2017, 10:28 pm | #3 |
Heptode
Join Date: Feb 2011
Location: Southampton, Hampshire, UK.
Posts: 574
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Simple Capacitance Test Set (2)
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 |
4th Apr 2017, 11:15 pm | #4 |
Octode
Join Date: Dec 2010
Location: St Ives, Cambridgeshire, UK.
Posts: 1,180
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Re: Simple Capacitance Tester
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
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Invisible airwaves crackle with life. Or they should do. BVWS Member |
4th Apr 2017, 11:23 pm | #5 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: Simple Capacitance Test Set (2)
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. |
5th Apr 2017, 2:06 am | #6 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Simple Capacitance Tester
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. |
5th Apr 2017, 8:35 am | #7 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Simple Capacitance Tester
Similar one here:
http://www.radiomuseum.org/r/sulliva..._test_set.html Are there any resistors in there? Lawrence. |
5th Apr 2017, 9:04 am | #8 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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Re: Simple Capacitance Tester
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.
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5th Apr 2017, 10:32 am | #9 |
Heptode
Join Date: Apr 2010
Location: West Midlands, UK.
Posts: 663
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Re: Simple Capacitance Tester
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. |
5th Apr 2017, 8:54 pm | #10 |
Heptode
Join Date: Feb 2011
Location: Southampton, Hampshire, UK.
Posts: 574
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Re: Simple Capacitance Tester
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 |
6th Apr 2017, 1:29 pm | #11 |
Heptode
Join Date: Feb 2011
Location: Southampton, Hampshire, UK.
Posts: 574
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Re: Simple Capacitance Tester
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 |
25th May 2017, 8:21 pm | #12 |
Heptode
Join Date: Feb 2011
Location: Southampton, Hampshire, UK.
Posts: 574
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Re: Simple Capacitance Tester
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 Last edited by Hammonds; 25th May 2017 at 8:21 pm. Reason: typo |