O V E R V I E W
The purpose of the Warm-U 2.0 is to maintain a consistent temperature (the SETPOINT) in a flowing-fluid type physiology bath.
The Warm-U also displays and electrically outputs the bath temp, and gives a warning if this gets too far from the setpoint.
At the core of the device is a miniature thermostatically controlled water bath in the form of a U shaped pipe. (the 2 ends of this pipe can be seen protruding through the top of the box) A thin tube carrying ACSF to a physiology bath first snakes through this "warm-U", and in doing so warms up the ACSF.
On the way to the prep in the physiology bath after exiting the U, the ACSF loses heat to the environment, so the U needs to be substantially warmer than the desired bath temperature.
How much warmer? The user may figure it out empirically by slowly raising the U temp until the chamber is at the desired temp, OR he may let the Warm-U device do this automatically.
Manual "Direct U Control" works well in a very stable system - where ambient temp, flow rate, radiant flux, etc. remain constant. Automatic, or "Adaptive Control" corrects for changes in the system, for example if the flow rate changed.
D I P S W I T C H F U N C T I O N S
DIPSWITCH #1 C O N T R O L M O D E
Adaptive Control (Dipswitch #1 down): The temperature sensor in the physiology bath is used to slowly increase or decrease the U temp until the requested setpoint is achieved. It may take several minutes to stabilize. The user increases/decreases the bath setpoint in .1C increments with the Up/Dn buttons.
Direct U Control (Dipswitch #1 up): The temperature sensor in the physiology bath is used for display only, it plays no part in control. The user increases/decreases U temp directly with the Up/Dn buttons. The U temp setpoint is displayed as a 3 digit number, not a temp.
DIPSWITCH #2 D I S P L A Y M O D E
Normal (Dipswitch #2 down): Minimal info is shown
DEBUG (Dipswitch #2 up): Additionally shown are U setpoint; U actual; Bath Temp Correction
DIPSWITCH #3 M E M O R I Z E S E T T I N G S
Normal (Dipswitch #3 down): no action
Memorize (Dipswitch #3 upward): Bath Setpoint, U Setpoint and Bath Temp Correction are saved to non-volatile memory. These values will be remembered the next time Warm-U is powered up. A sound lets you know it memorized.
DIPSWITCH #4 C A L I B R A T E B A T H T E M P
Normal (Dipswitch #4 down): no action
Calibrate (Dipswitch #4 up): This function allows an offset to be applied to the Warm-U's bath sensor so that it more accurately reflects the true temp of the prep. Note: temperatures in a physiology chamber vary by 5C or more depending on location. If calibration isn't done correctly, the Warm-U sensor will give incorrect values. To calibrate, the system must be fully up and running (i.e. flow rates, microscope lens position, slice position, microscope lamp brightness, etc, all at experiment status).
Place a laboratory- grade temp sensor on the slice. Now, use the Up/Dn buttons until the Warm-U's "Bath Temp" matches that of the fancy temp sensor. Calibration done... put Dipswitch #4 back down. Memorize may be performed now, and so long as the position of the Warm-U's bath sensor doesn't change, the calibration should stay valid.
1) Place the Warm U as close to the physiology chamber as practical.
2) Connect Warm-U to DC power supply, 12-14 volts. 2 amp is sufficient.
3) Insert the teflon tube which feeds the chamber through the Warm-U. The run to the chamber should be as short as possible, and "sleeved" with a bigger tube to reduce heat loss.
4) Fill the U with water. Water must be visible in the clear tubing at the top. A Parafilm wrap will prevent this water from evaporating over time.
5) Place the small white sensor in the chamber. It should be sitting low and "in the flow" as much as practical without interfering with electrode and slice positioning. Fix it to chamber rim with sticky wax.
6) Turn it on, and (with normal ACSF flow rate) after 15 minutes you may perform the calibration (described above).
CONTACT CARL WITH ANY QUESTIONS COMMENTS OR ISSUES!