PCB update

IMG_1799

I’ve recently created a PCB for my STM project and updated the electronics page. I’m now using digital feedback and linearizing the tunneling current data in software using a logarithmic lookup table. This really stabilized the feedback loop and I’m now able to get atomic resolution in constant current mode, something which I just couldn’t get to work with the previous analog feedback loop. I’m also using sigma-delta modulation to increase the resolution of the scanner drive signals from 16-bit to 20-bit. The previous electronics page describing the breadboard prototype with analog feedback is still available and can be found here. I’ve also added some images acquired with the new system to the gallery.

Graphite atoms. Constant current. 50 mV, 1 nA.

Graphite atoms. Constant current. 50 mV, 1 nA.

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