TCHF Instructions

The TCHF (Temperature Control High Frequency) control unit provides reliable temperature control using high frequency alternating current that won't disrupt precision optical magnetometry measurements.

Twinleaf's TCHF controls the power of the heater rather than the voltage or amplitude. Power is related to the square root of the rms-voltage (Vrms) through the equation P = Vrms2/R.

Features

Operation

To turn on the TCHF:

  1. Plug the unit into mains power.
  2. Connect a USB device for control
  3. Connect a heating/temperature measurement device. Use either the Output/RTD BNC connections, or the four pin LEMO connector. Do not use both at once!
  4. Turn on the main power switch, located on the back panel. The small LED on front should begin blinking.

Communication between your computer and TCHF can be done through Python or Labview.

Python Setup

Installing Python and TIO

First, install Python. Instructions for this can be found on our Getting Started With Python page.

Next, you will need to install TIO to monitor and communicate with your TCHF. Instructions for this are found on our Getting Started With TIO Python page.

Finally, it is useful to set up a proxy server so that you don't need to continuously specify the usb path when using itio and tiomon. To do this, following the tio-proxy instructions on our Getting Started With TIO Tools page.

Device Setup

Before use, it is necessary to specify a reference resistance and reference temperature related to the temperature sensor used. To do this, start communication with your device with the command:

% itio

If you do not have a proxy server running, you will need to specify the usb path here. Then, to specify your reference resistance and temperature, using the following commands:

  1. Specify the sensor type using

    >>> tio.tchf.therm.sensor.type(TYPE)

    where replacing TYPE with 1 refers to RTD and replacing with 2 refers to NTC thermistor.

  2. Set the sensor temperature coefficient using

    >>> tio.tchf.therm.coef(COEF)

    which may be ⍺ = 0.003850 for platinum RTDs or β = 3250 for NTC thermistors obeying the Steinhart–Hart equation.

  3. Set the sensor reference resistance with

    >>> tio.tchf.therm.r0(RESISTANCE)

    where RESISTANCE is replaced by the resistance value in Ohms.

  4. Set the sensor reference temperature with

    >>> tio.tchf.therm.t0(TEMP)

    in degrees C if different from 20 C.

Setting a Temperature

To begin using your TCHF, use the following commands:

  1. Set a temperature in degrees C with:

    >>> tio.tchf.pid.setpoint(TEMP)

  2. Enable this change with

    >>> tio.tchf.pid.enable(1)

  3. Finally, to view the output power, use

    >>> tio.tchf.heater.power()

There are additional itio commands for our TCHF for more specific use (setting a maximum power, setting the heater amplitude, etc). Refer to the command line reference for additional features. To exit itio, type exit(). Finally, for a livestream of your TCHF settings and output, use the command

% tiomon

Again, the usb path will need to be specified with this command if you are not using a proxy server.

LabVIEW Setup

Twinleaf also provides a LabVIEW VI for communications with the TCHF. A screenshot is shown below.

TCHF VI

To begin heating, press the Heater Enable button. This will turn on the PID loop, which will seek to reach the temperature in the Temperature Set input box.