MESA THCAD-10 trouble

Hello...

Long time ago I bought THCAD-10 card, but before card was arrived the my project was abandoned.

But now I have other project and I want to use that card lying in original package all that years and found that output is strange. As from datashet seems that it should be linear Voltage to frequency but as I supplyed voltage from power supply with 1V step and measuring results with oscilloscope I found that output seems more logharitmic than linear. Is That normal???

The jumpers was in Unipolar and F/128.

Attached is pdf with measurements. The 0V and 10V calibration from THCAD sticker seems to be valid. But linearity not.

Why didn't you measure frequency in Hz?

Every other example where I have seen people do similar measurements, the device was linear.

It has same result. 1/f=time and vice versa. So linearity should be same in both directions.

Here's the (scaled in Khz) inverse of your data:

0,0.940733772
1,1.597444089
2,2.304147465
3,2.96735905
4,3.663003663
5,4.273504274
6,4.95049505
7,5.617977528
8,6.289308176
9,6.944444444
10,7.575757576

And here is the plot of that data



The frequency with respect to input voltage is linear, the period is not. The V-F linearity is typically better than .02%

Hmm indeed with frequency is linear...
...but sadly just destroyed the card as I plug wrong connector on wrong place, supplyed 10V on +5V input.

eslavko wrote:

Hmm indeed with frequency is linear...
...but sadly just destroyed the card as I plug wrong connector on wrong place, supplyed 10V on +5V input.

That must be your pennance for doubting the great PCW

PS. Now I don't know what smiley to add

repair or not to repair. That's question now. probably all the chips on computer side are toasted. all except isolator are cheaps...