Shim Amplifier -------------- .. figure:: /images/peripherals/shim/front_angle.jpg :width: 100% :align: center Shim Amplifier front .. figure:: /images/peripherals/shim/back_angle.jpg :width: 100% :align: center Shim Amplifier rear This module allows you to drive up to 8 shim coils with current controlled output of up to 1 Amp. Features: - 8 channel shim amplifier - Dual Heater Driver Connections ^^^^^^^^^^^ On front of the Shim Amplifier module you will find the on/off power switch and the indicator lights. The top indicator will illuminate green when the module is powered on, while the bottom indicator will illuminate blue when the amplifier is enabled via the interlock. .. figure:: /images/peripherals/shim/shim_amp_front.png :width: 100% :align: center Front controls & indicators The 24 V power port, Shim in/out connectors, I/O port and temperature control connectors can be found on the back of the module. .. figure:: /images/peripherals/shim/shim_amp_back.png :width: 100% :align: center Rear ports Setup Guide ^^^^^^^^^^^ This section will guide you through the steps required to connect and power the Shim Amplifier Module with the Kāhu Spectrometer. .. warning:: **Ensure the Shim Amplifier module is not powered on during Kāhu power up and shutdown.** **Step 1 - Rear Cable Connections** Begin by arranging the modules as shown in the image below with the Kāhu Spectrometer placed on top of the drive module(s). Note that the image below also shows the Gradient module in the stack-up. This module is not required to run the shim amplifier, and if it is not being used simply place the Shim amplifier module to the side of Kāhu. .. figure:: /images/peripherals/shim/stacked.jpg :width: 100% :align: center Kāhu, Shim & Gradient Amplifier modules stacked Complete the initial rear Kāhu connections as explained in the Kāhu Hardware :ref:`setup:Connections` section. Connect the 24V, 120 W external power brick to the shim amplifier. .. figure:: /images/peripherals/shim/power.jpg :width: 100% :align: center Power supply: 24V, 120W Fasten the 10 pin I/O connector to the Shim Amplifier's I/O port using the provided drive tool, H2.0. **Take care to not overtighten.** .. figure:: /images/peripherals/shim/IO_cable.jpg :width: 100% :align: center IO cable connection, shim amplifier side Connect the other end of the I/O cable to Kāhu's interlock and PT100 ports as shown. .. figure:: /images/peripherals/shim/IO_cable2.jpg :width: 80% :align: center IO cable connection, Kāhu side Connect the provided Shim control cable between the Shim In port on the Shim Amplifier Module and the Shim port on Kāhu. Should you need to replace this cable, the part number is Samtec FCF8-20-01-L-12.00-S_. .. _FCF8-20-01-L-12.00-S: https://www.samtec.com/products/fcf8-20-01-l-12.00-s .. figure:: /images/peripherals/shim/shim_cable.jpg :width: 80% :align: center Shim control cable connection .. note:: **The shim control cable is oriented with the gold contacts facing upwards when connecting to Kāhu, but facing downwards when connecting to the amplifier module.** Finally, connect the shim out port to your shim coils. You will need to build our own cable for this connection. The mating connector required for the cable is the Harwin M80-4141698_ and the arrangement of the shim channels from the amplifier is shown below. .. _M80-4141698: https://www.harwin.com/products/M80-4141698 .. figure:: /images/peripherals/shim/shim_pinout.png :width: 80% :align: center Shim output connector, Shim Channels **Step 2 - Power Up** Power on Kāhu and establish a network connection from your PC. Once Kāhu power up has finished, you can power on the Shim Amplifier with the power switch. Specifications ^^^^^^^^^^^^^^ General """""""" .. list-table:: :header-rows: 0 :width: 100% :widths: 70 200 :align: center * - Power Supply - 24 V, 120 W * - Dimensions - 150 x 200 x 65 mm (Width x Depth x Height) * - Weight - 1 kg .. todo:: Kerry check dimensions and weight Heater Driver """"""""""""" .. list-table:: :header-rows: 0 :width: 100% :widths: 70 200 :align: center * - Channels - 2 * - Output Voltage - 24 V * - Max total output current - 2 A [#heatf1]_ * - Mating Connector - `Adam Tech MMI-M0PG05S52 `_ .. [#heatf1] With only one channel in use, the minimum load resistance is 12 Ω. With both channels in use each load must be at least 24 Ω, or otherwise configured so that the total current does not exceed 2 Amps. Shim Drivers """""""""""" .. list-table:: :header-rows: 0 :width: 100% :widths: 70 200 :align: center * - Channels - 8 * - Input Range - ±5 V, single ended * - Transconductance Gain - 0.2 A/V * - Output Voltage Range - ±5 V * - Output Current Range - ±1 A * - Shim Coil Resistance - 3 - 5 Ω Detailed Description ^^^^^^^^^^^^^^^^^^^^ Amplifier """"""""" Each shim amplifier channel consists of a single stage voltage controlled current source. The output current will be proportional to the input voltage according to the following transfer function: .. math:: I_{out} = 0.2 * V_{in} I/O Port """""""" The part number for the mating connector used in the I/O cable privided (on the amplifier side) is the `M80-4141298 `_. The pinout of the *I/O* port on the module is: .. list-table:: :header-rows: 1 :width: 70% :widths: 70 200 :align: center * - Pin No. - Description * - 1 - PT100 1+ output * - 2 - PT100 1- output * - 3 - PT100 1 reference output * - 4 - PWM 1 input * - 5 - PWM 2 input * - 6 - Interlock input * - 7 - PT100 2+ output * - 8 - PT100 2- output * - 9 - PT100 2 reference output * - 10, 11, 12 - GND .. figure:: /images/peripherals/shim/shim_io_conn.png :width: 70% :align: center Shim IO connector pinout .. note:: Do not connect a PT100 sensor to this port, instead use the T-1 or T-2 port(s) as described in the :ref:`hardware/shim_amplifier:Temperature Control` section below. Temperature Control """"""""""""""""""" Two independent heaters can be driven by the module via the T1 and T2 ports. Using the :ref:`dashboards:Temperature Control` tab of the *System* dashboard, the duty cycle of the heater driver can be automated to achieve a temperature set point. The mating connector required to build the temperature control cable is the `Adam Tech MMI-M0PG05S52 `_. The pinout of both temperature control ports on the module is as follows: .. list-table:: :header-rows: 1 :width: 60% :widths: 70 200 :align: center * - Pin No. - Description * - 1 - Heater + * - 2 - Heater - * - 3 - PT100 Reference * - 4 - PT100 - * - 5 - PT100 + .. figure:: /images/peripherals/shim/temp_ctrl_conn.png :width: 40% :align: center Temperature control ports pinout .. caution:: **To avoid damage, take care to align the red orientation markers on the connector and port** Maintenance """""""""""" To ensure the module doesn’t begin to overheat, the dust filters should be cleaned regularly. To access the filters, ensure the module is powered off then remove the 4 screws on the panel on the under side of the module as seen below. The filters can then be removed, cleaned, and refitted. .. figure:: /images/peripherals/shim/dust_filter.jpg :width: 100% :align: center Dust filter cover removed .. note:: **Ensure filters and panels are refitted before the module is powered back on.**