Thomas Witzel

Relax2.0, a graphical user interface for OCRA

Hello OCRA and Tabletop community, In this blog post, I will share the news about the first GitHub publication of my Relax2.0 graphical user interface (GUI) for OCRA. Relax2.0 is based on the original OCRA server for the Red Pitaya by Thomas Witzel and the PyQt GUI Relax by David Schote. Relax2.0 can be downloaded…

18 May

Testing the transmit and receive functionality of the OCRA Tabletop MRI System

Hello OCRA and Tabletop community, In this blog I will guide you on how to test the RF functionality of the OCRA Tabletop MRI System. We will test the functionality for receiving RF spin signals (RX) and transmiting RF pulses (TX). For the tests you need a pickup loop coil. The coil can be build…

18 Apr

RF-Coil for the OCRA Tabletop MRI system

Hello OCRA and Tabletop community, In this short blog I will share my radiofrequency (RF) -coil design for our OCRA Tabletop MRI system. The coil is a simple solenoid design. To make it sensitive to the measurement (Larmor) frequency it is built as an electrical resonator with parallel capacitance. To match its impedance to a…

15 Dec

Small Scale 600W Gradient Power Amplifier

Hello OCRA and Tabletop Community, I would like to introduce the low-cost 4-channel 600 W Gradient Power Amplifier (GPA) for our OCRA Tabletop MRI system. Basically, the GPA converts a voltage input coming for example from the OCRA1 (see blog post from Marcus) into currents to supply gradient coils. The GPA can handle gradient sequences (pulsed…

30 Sep

Transmit-Receive Switch for the OCRA Tabletop MRI system

Hello OCRA and Tabletop Community, In this blog I will share my Transmit-Receive (TR) switch design for our OCRA Tabletop MRI system. As it’s a general design, it also can be used for small RF-power applications in other MRI systems. The TR-switch is used to connect the RF-coil (antenna) to the RF Power-Amplifier (RFPA) in…

27 Nov

OCRA1 – SPI controlled 4 channel 18bit DAC and RF Attenuator

Hello OCRA Community, I would like to introduce you to one of the core elements of our OCRA Tabletop MRI console, the OCRA1. It’s a peripheral printed circuit board (PCB) that extends a Red Pitaya to a basic MRI console. All its components are controlled with the Serial Peripheral Interface (SPI) bus given by the…

Welcome to the OCRA blog!

What started in a little corner of my tiny Boston apartment, and then later advanced with the help of numerous students that shall be listed soon on this page has now become a project bigger than just my hobby, with users and contributors in both Europe and the USA. In order to keep the community…

Author: Thomas Witzel