Boonton 72BD

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Phil Hobbs 13 years ago

When I saw that there was a Boonton 72BD 3-1/2 digit capacitance meter going for $100 on eBay, I couldn't resist. It's the tarted-up version of the analogue 72A that I have on my bench (and for which I paid $230, still a good deal).

It arrived today, and it's in perfect shape--if you zero it, the display sits there showing 0.000 pF all afternoon. It measured a bunch of 2% polystyrene caps to within 2%, from 100 pF to 1500 pF, and did a good job on other caps down to 1.0 pF (which are the smallest I have with leads). If you wave your hand nearby, you can make the display move by femtofarads very easily. It's almost good enough for a capacitive gauge.

I have a couple of projects for which I care about tens of femtofarads, so this addition to the arsenal is very timely indeed.

Awesome.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net

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tm 13 years ago

Good score! Congrats.

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John Larkin 13 years ago

We have a couple of the analog versions. Wonderful gadgets. They have built-in bias tee capability, and very low AC excitation voltage, so you can measure diode c-v curves easily.

John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation

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Jan Panteltje 13 years ago

On a sunny day (Fri, 07 Dec 2012 15:37:06 -0500) it happened Phil Hobbs wrote in :

Do not want to rain on your parade, but:\

panteltje: ~/compile/pantel/fpga/jps # lcp -d /dev/ttyUSB0 Panteltje lcp-0.7 using device /dev/ttyUSB0 Hit space bar to calibrate, Escape to exit.

4.373 pF 4.611 pF 4.650 pF 4.650 pF 4.611 pF 4.650 pF polystyrene caps to within 2%, from 100 pF to 1500 pF, and did a good

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Phil Hobbs 13 years ago

Yours is sure noisy when it isn't reading zero. How come?

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net

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John Larkin 13 years ago

Your schematic is unreadable, and the Rice link is broken.

The Boonton meter does 2/3/4 terminal measurement with low-level sinewave excitation and a phase-sensitive detector. It's great for measuring semiconductor junction capacitance vs voltage, or a small capacitance at the end of some long cables or PCB traces. Higher voltage oscillator or ramp-type c-meters (like the very nice AADE unit) aren't suited to measuring semiconductors and also get confused by series or shunt resistance, or capacitances to ground.

Capacitance can be measured accurately from attofarads to kilofarads, a huge dynamic range.

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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Jan Panteltje 13 years ago

On a sunny day (Sat, 08 Dec 2012 13:14:07 -0500) it happened Phil Hobbs wrote in :

Yes it is, lemme try again: Panteltje lcp-0.7 using device /dev/ttyUSB0 Hit space bar to calibrate, Escape to exit.

-0.276 pF

-0.237 pF

-0.276 pF

-0.237 pF

-0.276 pF

-0.237 pF

-0.276 pF

-0.237 pF

-0.276 pF

-0.237 pF delta is .039 pF

-0.276 pF

-0.237 pF

-0.276 pF

-0.237 pF

-0.276 pF

-0.276 pF < - space bar

0.000 pF 0.000 pF 0.000 pF 0.000 pF 0.000 pF 0.000 pF

-0.039 pF

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amdx 13 years ago

An "improved" inductance / capacitance meter by Phil Rice VK3BHR Actually, it works much the same as the original.

formatting link

Mikek

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Phil Hobbs 13 years ago

dig

It does sound useful. I have a bunch of gizmos like that lying around, e.g. a curve tracer specifically for pHEMTs.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net

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John Larkin 13 years ago

That looks very similar to the AADE unit. It even has the same part values.

formatting link

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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Robert Baer 13 years ago

Far Out! I do not have to spend $200 for a complete professional meter; i can spend a lot more plus time to make it myself and have something that looks so-so. Neat!

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John Larkin 13 years ago

The AADE LC meter (the one that Rice stole the design of) is $129 fully assembled/tested/calibrated. It's a great little gadget.

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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Robert Baer 13 years ago

Well, in that case, lemme know how i can buy that (assuming that royalties are now being paid).

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John Larkin 13 years ago

formatting link

He publishes the schematic, and lots of people copy it verbatum.

John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation

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ehsjr 13 years ago

formatting link

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Robert Baer 13 years ago

Thanks.

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DaveC 13 years ago

Any options on your unit?

Dave

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Phil Hobbs 13 years ago

I have one with the 15 mV excitation and one with 100 mV. (There was another one that went for $80.) ;)

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net

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John Larkin 13 years ago

Do you have the 2-wire and 4-wire adapter thingies?

John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation

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Phil Hobbs 13 years ago

I have one with two spring posts (72-5B), two with the three spring posts (72-4B), and one with the four BNCs (72-5C). I haven't gotten as far as figuring out how to use the four-way one yet, though I do have the manual. It looks like it just computes the difference of the capacitances between the centre conductors of the two pairs.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net

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Boonton 72BD

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