Voltage detectors how work?

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physis

physis

Senior Member
Re: Voltage detectors how work?

I can't take it anymore! :D

My Greenlee tic tracer is now an engineering sample.

I'll disect this thing in whatever intervals suit me.

To start the circuit:

R's 1 & 2 are 3.95M & 500M respectively.

R1 is signal and R2 is shunted for noise stability.

I beleive it boasts a sensitivity to 50v or more.

That gives the signal input a minimum sensitivty magnitude of 12.58 uA.

Here's where you come in Rattus:

There are no discrete capacitances before the input terminates to the IC. The IC is a "TI" component

38F6VCK

I don't have any current data references for this stuff but I figure you might know some guys or have more ready access?
 
R

rattus

Senior Member
Re: Voltage detectors how work?

Sam,

Give us a schematic or at least a net list. Also look for large areas of copper on the PC board. These could be capacitor plates. You might even give us a picture.
 
physis

physis

Senior Member
Re: Voltage detectors how work?

One side of the board is a ground plane. Interestingly there's a gound trace under the two input signal resistors.

I seriously dought there's any attempt to use the board as a capacitor. There's no configuration on it that would cause me to suspect that and it doesn't make much sense anyway, discrete capacitors are cheap and far more accurate.

TI is Texas Instruments and Rattus is an Ex TI man.

[Probe lead]--R1--R2--Gnd

The junction of R1 and R2 is the signal to pin 13 of the IC. It's a 14 pin CMOS. I'm guessing dual OP amp but comparator sounds good to.
 
physis

physis

Senior Member
Re: Voltage detectors how work?

I can't find the part No. either. I don't have the thing with me right now, I'll make sure I have the right number.
 
R

rattus

Senior Member
Re: Voltage detectors how work?

Sam,

Your ground plane is one plate of C2! There is somewhere another plate which is part of C1.

I have been away from TI since 1971, and all my old buddies have retired.

I know! I will ask the smartest man alive next time I see him--in about a week or so.
 
physis

physis

Senior Member
Re: Voltage detectors how work?

P/N update: I think it might be 38F5VCK.

It looks like the ink is more expensive than the device so they use very little of it. :D
 
physis

physis

Senior Member
Re: Voltage detectors how work?

It's kind a funny that you swear by your Greenlee, of the two I had I chose the Greenlee to be sacrificed.

It was because it has an on off switch at the top and when you turn it off too far (some of you know what I mean :D ) the cap comes off and the batteries donate themselves to the sidewalk or where ever it is you happen to be at the time.
 
physis

physis

Senior Member
Re: Voltage detectors how work?

And the cap tries to disappear too so it can never be used again and I have to go buy another Greenlee. :D
 
physis

physis

Senior Member
Re: Voltage detectors how work?

I swore "at" my Greenlee, :D .

I wonder if they have the slightest clue about it? :D
 
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