Curves Tracer

fig.1 Curve Tracer schematic
fig.1 Curve Tracer schematic

Description:

In my first version, inspired by an article [2], I have modified the circuits inserting an audio oscillator instead of rectified AC power line... then I loved & used it very much. Some years ago I saw another project, written by an italian magazine [3] and that you can see above in schematic form. Actually I'm studing the circuit and, as you can see, I identified all block.

But before achieve it I want to make some changes.

The problems of this solution,imho , are the TDA IC is oversized for its job further the blanking circuits are miss.

 

For the first problem one buffer in push-pull configuration is a suitable solution.

For the second one... I don't thought at nothing by now... 

When I finish blanking circuits I achieve it and I'll upgrade the page.

Simulation Screen-Shots:

fig.2 Chars
fig.2 Chars
fig.3 Output Voltages (Y&X scope's chans))
fig.3 Output Voltages (Y&X scope's chans))
fig.4 DUT Voltages (NPN-BJT in example)
fig.4 DUT Voltages (NPN-BJT in example)
fig.5 Vstep & Vsaw
fig.5 Vstep & Vsaw

Updates:

fig.6 Push-Pull add-on zoom
fig.6 Push-Pull add-on zoom

I have substistute the TDA with the push-pull . I have test with bjt NPN type and works well. Obviusly this is a general test in the final scheme I put a Vbe-Multiplier instead that diodes and a polarizzation review is required.

The polarization review is required because the step-signal must to be a bipolar (as you can see in fig.9 the signal Step is unipolar  in this test). In  scheeme you can see the  circuit for DC-shift is disabled (in gray).

In this test the Howland's current pump is disabled too.

The test promise well....

fig.7 Test of push-pull for BJT NPN type
fig.7 Test of push-pull for BJT NPN type
fig.8 Vy(t) & Vx(t)
fig.8 Vy(t) & Vx(t)
fig.9 Step & Saw signals
fig.9 Step & Saw signals

References:

[2] - Kaz Sunamura

[3] - Nuova Elettronica

 

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