One for the books - or gamblers.

[itsmoked]

Here is a schematic I am to assemble. The author of this misbegotten rag is gone and hopefully the fish enjoyed his company and fine corals are living on his cement shoes..

Here is today's problem:

The capacitance meter is a high end Fluke unit that uses 1kHz, 10kHz, or 100kHz to figure out the R, L, and C.

The 'device' is just a crummy quality capacitor with about 0.010uF of capacitance.

I appears to me that the bottom three elements do nothing.

Can anyone suggest if this circuit does anything I'm not seeing?

Keeping in mind that other things on this schematic were blatantly wrong that I've sorted out, can you suggest a logical "correct" connection to the test device?



Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

Seems like the intent is to put them in series with the CUT, but that would mean putting 2 0.02 uf in series with the CUT...

TTFN

FAQ731-376

 

[waross]

Keith, will the 10M resistors pass enough current to affect the test? (Too lazy and not enough time to calculate the Xr at different frequencies this morning.)
From power basics, the phase angle of the test current will be changed by the relative currents through the resistors and the capacitors.
You can replace the circuit with one 0.01 uF with double the voltage rating, shunted by a 2 m Ohm resistor.
Is the intent to test capacitors so tiny that they may be damaged by the test current or voltage of the fluke? If so, this may be an attempt to design a voltage divider.
Please let us know how the circuit responds under test!

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[VEBill]

The problem with badly laid-out schematics is that blatent errors are easy to miss. Such as those three useless, do-nothing components at the bottom.

LOL - perhaps they're spares - LOL.

 

[waross]

The worst part of feeling this foolish is knowing that I deserve to feel this foolish. Thank you for being gentle with me. LOL, LOL

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

LOL
Yeah I just glanced at this circuit and bought the parts. Now soldering iron in hand, I stare dumbly at what is before me.(that I missed)

I think IR may be correct. These are supposed to be two sets - one in each lead of the test circuit. The ugly part is that that requires two drafting errors instead of just one. That vertical line needs to go away and the top line needs to have the top set in it. (actually three errors then!)

The capacitor under test will first have had 5kV across it. The FLuke can have only 40V into it. Perhaps the 10M ohm resistors are to protect the Fluke even though there is a discharge position that is supposed to isolate and discharge the cap-under-test before reaching the Fluke testing mode.

<sigh>

I will be trying that first. Luckily they've given me test data to show what value they expect to get.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

The problem I think I see is that there will be two capacitors in series with the test cap, all in the same capacitance range.

So unless there's an B-A mode, the measurement would be contaminated by the extra capacitors.

TTFN

FAQ731-376