TC-1 TEMPERATURE CONTROLLER INSTRUCTION MANUAL

Transcription

1 TEMPERATURE CONTROLLER INSTRUCTION MANUAL May, 1997 Copyright by N.B. Datyner, All rights reserved. Cell MicroControls, PO Box 10531, Virginia Beach, VA Phone: (800) 398-4CMC; Fax: (800) 398-9CMC; WWW:

2 TABLE OF CONTENTS PAGE INTRODUCTION...3 CONTROLS, INDICATORS, INPUTS AND OUTPUTS FRONT PANEL...3 TEMP TEMP TEMP 1,2 SWITCH...4 POWER...4 HEATERS A,B...4 ON//OFF...4 LO BATT....4 REAR PANEL V...4 OPERATE/CHARGE...5 TEMP IN...5 EXT TEMP REF...5 INT REF/EXT REF...5 HEATERS A,B...5 FUSE A,B...5 B GAIN...5 INTEGRATOR ON/OFF...5 R p... 6 R C... 6 ELECTRICAL CONNECTIONS...6 SPECIFICATIONS...6 THEORY OF OPERATION...7 TUNING PROCEDURE B GAIN...8 R p...8 R c...8 TROUBLESHOOTING & HINTS...9 TC-1 doesn't work...9 True bath temperature...9 The heater LED's don't light...9 Using HEATER B as main heater...9 Hypodermic tubing to protect thermistor...10 Where does everything go?...10 Bath assembly...10 Thermistor placement...11 Pre-heater assembly...12 HPRE and HPREC...12 Using HC-1 heater with TC Electrical connections...12 Pre-heater...12 Thermistor position...12 Tuning procedure...12 HC-1 Mechanical assembly...13 APPENDIX Additional items...14 Plans for BT-1 bath...14

3 INTRODUCTION The TC-1 Temperature Controller and H-1 Heater form part of a temperature control system that yields reliable and accurate temperature control in small experimental chambers used for studying acutely isolated or cultured cells. The TC-1 accepts the Recorder Output of a YSI-43TD tele-thermometer (connected to a miniature thermistor probe) and compares this voltage with an internal reference voltage set either by manual controls or by external programming. The difference between these two voltages, the error signal, is then used to generate appropriate power in the heater so as to maintain the chamber temperature at the reference temperature during changes in flow rate or ambient conditions. In general, when the reference temperature is increased in a step, the temperature in the experimental chamber overshoots before settling; the TC-1 works to minimize this overshoot, thereby protecting the cells from damage due to transient high temperatures. (The estimated temperature overshoot in response to a temperature jump of 10 C is approximately 2 C at the bottom surface of the BT-1 Bath). With proper adjustment of the controller parameters the temperature across a 0.6x1.0cm surface can be regulated within ±1 C for flow rates of zero to 2ml/min. The rate of rise of temperature depends principally on the experimental chamber volume. Typically rates of 1 C/sec can be expected with chamber volumes less than 0.25ml. The rate of decay of temperature depends on the experimental chamber design as well as the solution flow rate. For the BT-1 Bath decay rates range from approximately 30 secs at a flow rate of 2ml/min to 112 secs for a flow rate of 0.2ml/min. Further details of the performance of this type of system is described in Datyner, Gintant and Cohen (1985). The H-1 heater consists of a finely stranded heater element (strands 40µm wide, 250µm separation) sandwiched between thin layers of glass. This arrangement provides a uniform heat source approximately 0.5mm thick and largely transparent thereby enabling its use with conventional or inverted microscopes. Datyner N.B., Gintant G.A. & Cohen I.S. (1985) Versatile temperature controlled tissue bath for studies of isolated cells using an inverted microscope. Pflügers Archiv 403, FRONT PANEL CONTROLS, INDICATORS, INPUTS AND OUTPUTS N B D TEMPERATURE CONTROLLER HEATERS ON A 15 TEMP 1 40 o C 15 TEMP 2 40 o C % POWER B LOW BATT. TEMP 1 Reference temperature 1. The temperature controller uses this as the reference temperature when the TEMP 1,2 switch is set on TEMP 1. TEMP 2 Reference temperature 2 (see TEMP 1). 3

4 TEMP 1,2 SWITCH Selects TEMP 1 or TEMP 2 as the reference temperature. between two preset reference temperatures. This control allows reproducible switching POWER This control regulates the power available to HEATERS A and B. During normal operation (ie. when there is solution in the experimental chamber) this control is set to the 100% position. When the chamber is being drained of solution or loaded with cells this control should be set at 0%. Reducing the available power to zero is preferable to switching the TC-1 off, since this avoids the possibility of temperature transients when the TC-1 is turned on. The POWER control can also be used to slow the rate of rise of temperature if needed (halving the available power will halve the rate of rise of temperature). Since it is essential to have sufficient power for steady state maintenance of temperature, the application of this method is limited. Where slow temperature changes are desired it is preferable to either raise the temperature manually using the TEMP 1,2 controls or use the EXT TEMP REF to program a slow ramp. HEATERS A: the intensity of the LED reflects the voltage at the HEATER A output. For most reference temperatures the LED will glow only dimly, if at all. However, during temperature steps the LED will light. If the FUSE is blown or the 12V battery voltage falls below approximately 8V the LED will not light. B: see A: ON/OFF SWITCH This switch turns the temperature controller ON or OFF and lights the LED below it when the TC-1 is ON (OPERATE/CHARGE switch must be in OPERATE position). LO BATT. This LED lights when the internal battery voltage is low (less than 7.4V). If the batteries were initially fully charged, the controller can be used safely for approximately 5 hours after this LED comes on. REAR PANEL 12V OPERATE TEMP IN EXT TEMP REF INT REF HEATERS A B FUSE B GAIN 2 RP 3 CHARGE EXT REF A FUSE 1 4 INTEGRATOR ON RC B OFF +12V Input of +12V at approx. 2.5 Amp max, usually a 12V battery. A fully charged 17 Ampere-Hour battery should provide power for well over 12 hours when both HEATER A and B are used. 4

5 OPERATE/CHARGE During normal operation of the TC-1 this switch should be on OPERATE. Switching to CHARGE disconnects the +12V input from the TC-1 and reconnects it to a charging circuit for the internal batteries. (The 12V battery should be charged using the recommended chargers. Both the 12V battery and internal batteries can be charged simultaneously if the 12V battery is left connected to the TC-1 and the 12V battery charger is attached to the 12V battery or +12V input.) Charging of the internal battery takes approximately hours. With the switch set to CHARGE the ON/OFF SWITCH should be in the OFF position, otherwise charging will be slowed by the current drain of the TC-1. The internal battery must be charged, for the TC-1 to perform properly. Once the LO BATT. indicator is lit the TC-1 will function normally for approx. 5 hours (if the batteries were initially fully charged). After this time the TC-1 switches to a shut-down state in which :- a) HEATER A,B outputs are held at less than 1V, b) the TC-1 no longer responds to the POWER or TEMP 1,2 controls and c) the YSI-43TD temperature reading may be distorted (lowered) by the TC-1. The TC-1 should then be charged as recommended above (see OPERATE/CHARGE). TEMP IN This is the input from the Recorder Output of the YSI-43TD tele-thermometer (see ELECTRICAL CONNECTIONS below). Other transducing devices can be used as inputs provided V(T) x T (in C) Volts where T is the chamber temperature in C and V(T) is the output voltage of the transducer. A circuit is available to convert the output of a Sensortek probe (with 10mV/ C output) to an equivalent of the YSI-43TD Recorder Output. Please call for information. EXT TEMP REF The EXT TEMP REF is used for inputting an external reference temperature to enable programming of temperature jumps or ramps. The relationship between the reference temperature (T) and the equivalent input voltage V EXT TEMP REF is given by T x V EXT TEMP REF C V EXT TEMP REF in volts INT REF/EXT REF This switch selects TEMP 1,2 (INT REF) orext TEMP REF (EXT REF) as the source for the reference temperature. HEATERS A: Output to heater A. B: Output to heater B. FUSE A: Fuse protecting power amplifier A from short circuit of heater output A. B: Same as for A but protecting power amplifier B. B GAIN This control adjusts the ratio of the output voltage for HEATER B to that of HEATER A. When fully anticlockwise both heater output voltages will be identical. Other gains are indicated on the dial (adjust with a screwdriver blade such that the blade points to the desired gain.) See SET-UP PROCEDURE to determine appropriate B GAIN. INTEGRATOR ON/OFF This switch turns the integrator stage ON or OFF. During normal operation this switch is in the ON 5

6 position to eliminate steady-state temperature errors. The OFF position is used in the SET-UP PROCEDURE. In the OFF position the TC-1 becomes a conventional proportional controller where the temperature error is amplified and applied to the heaters. R P This control adjusts the amplification of the temperature error signal (see SET-UP PROCEDURE). R C This control adjusts the rate at which the temperature error is integrated (see SET-UP PROCEDURE) ELECTRICAL CONNECTIONS The electrical connections are illustrated below for the standard configuration of the TC-1. It is recommended that a 4Amp fuse be placed in the lead from the 12V battery. YSI-43TD RECORDER PROBE TC-1 4 Amp fuse +12V TEMP IN HEATERS A B V BATTERY THERMISTOR SPECIFICATIONS REFERENCE TEMPERATURE :15 C -40 C Range internally adjustable from 0-23 C (lower limit) to C (upper limit). Note: operation below ambient temperature is possible with pre-cooled solutions. HEATER OUTPUT : A: 0-5 Volts Fused at 1.5Amp. B: 0-9 Volts Fused at 1.0Amp. Maximum voltages can be increased to 6V with internal adjustment. SUPPLY VOLTAGE : Requires 12V at 2.5 Amp max. Typical current load, 0.5Amp. [You may increase the supply voltage to a maximum of 14V. Greater voltages will damage the TC-1 electronics.] INTERNAL BATTERY: 6xAA NiCd batteries. Should provide approx hours continuous use before the LO BATT. indicator lights. DIMENSIONS : 8.0 x 10.0 x 3.0 inches (LxWxH) FUSES : Type 3AG 1.5Amp 250V for both HEATER A and 1.0Amp for HEATER B. 6

7 THEORY OF OPERATION A block diagram of the temperature controller is shown below. The Recorder Output voltage of the YSI-43TD tele-thermometer is fed to the Error Amplifier via the TEMP IN input and compared with the reference voltage (corresponding to the reference temperature selected [TEMP 1, TEMP 2 or EXT TEMP REF]). The resulting amplified error signal (V E ) is fed directly to the Summing Amp and Rectifier and also to the Integrator. The magnitudes of the amplified error and integrated error signals are adjusted as described in the SET-UP PROCEDURE to allow rapid changes in temperature with minimal overshoot. The amplified error signal is essential in maintaining the chamber temperature at the reference temperature during changes in flow rate while the integrator enables zero steady-state temperature error to be maintained as it supplies a constant heater current in the absence of any temperature error. The controller has two output stages; one for the bath heater (A) and a second for the pre-chamber heater (B). The voltage (and hence power) delivered to the pre-chamber heater is larger than that to the experimental chamber heater by a constant factor, the B GAIN. B GAIN is set to the smallest value which will maintain the temperature of solution entering the experimental chamber at approximately 0.5 C below the reference temperature. If B GAIN is too large the temperature in the pre-chamber at reduced flow rates is much higher than the reference temperature. This causes oscillations in the chamber temperature and inadequate temperature regulation. TEMP IN EXT TEMP REF Error Amplifier - + EXT REF INT REF V E R C ON R P INTEGRATOR - + Summing Amp & Rectifier POWER Power Amp A 1A HEATERS A Heater A Integrator B GAIN TEMP 1 TEMP 2 1A B V ref Temperature Reference +12V +8V 8V reg Power Amp B Heater B 0V 0V TC-1 CHARGE 6xAA NiCd Low V- BATT. TEMPERATURE CONTROLLER OPERATE -7.5V Power Supply 7

8 R P 1.Set initial control positions : R C 1. Set initial control positions : TC-1 TUNING PROCEDURE Three controls B GAIN, R P and R C influence the steady-state and transient performance of the temperature controller. The values they are set to depend on the thermal properties of the experimental and pre-heater chambers as well as on flow rates used. First, B GAIN is adjusted and then R P and R C. R P finally is re-adjusted for optimum transient response. The TC-1 is shipped with R P set to 80%, R C set to 50% and B GAIN set at 1. If you are using the BT-1 and capillary pre-heater or HPRE and HPREC you should only have to set the B GAIN. The setting should be approximately at 1.4. If you are using another bath design or want to optimize the transient performance then you should perform the SET-UP PROCEDURE below. B GAIN For this adjustment an independent thermistor probe is required to monitor the temperature at the inlet side of the experimental chamber. This test point should be on the long axis of the heater element approximately 5mm left of the center of the element (ie. exactly opposite to the location of the thermistor probe used by the TC-1 Temperature Controller). 1.Set initial control positions : B GAIN at 1; R P at 80%, R C at 50%; INTEGRATOR ON Select TEMP 1 at 35 C; POWER at 100% 2. Adjust flow rate to a typical value that will be used in experiments. 3. Allow flow to stabilize and increase B GAIN until test point temperature matches that of the controller thermistor. If a second YSI-43TD tele-thermometer is not available measure the resistance of the independent thermistor-to work out the temperature use the probe calibration (see Note). For the BT-1 Bath and capillary pre-heater B GAIN should be between 1.4 to Adjust the flow rate to the maximum that will be used and measure the temperature at the test point. Similarly, repeat for the lowest non-zero flow rate. 5. If the temperature at the test point in these two cases is low or high by more than 1 C adjust B GAIN appropriately and check the test point again for the temperature at the typical flow rate. 6. It is preferable to use the smallest value possible for B GAIN as this prevents oscillations of temperature caused by overheated solution exiting the pre-heater. Note: eg. Fluke 8020 series DVM on 20kΩ scale or other meters where test current is less than 20µA - low test currents are necessary to avoid self-heating of the thermistor bead. B GAIN as determined above; R P fully clockwise; INTEGRATOR OFF, TEMP 1 at 25 C and TEMP 2at35 C, select TEMP 2; POWER at 100% 2. Adjust flow rate to typical value that will be used in experiments. 3. Monitor the HEATER A voltage with a chart recorder or DVM. 4. With the control settings above there may be sustained oscillations in the heater voltage. If so rotate R P anti-clockwise until oscillations just disappear. This sets an upper limit on R P. 5. Repeatedly switch from TEMP 1 to TEMP 2, reducing R P if there are significant oscillations in the HEATER A voltage following the switch. B GAIN as determined above; R P as determined above; R C fully anti-clockwise; INTEGRATOR ON; TEMP 1 at 25 C and TEMP 2 at 35 C and select TEMP 1; POWER at 100% 2. Switch between TEMP 1 and TEMP 2 and measure the rate of rise of temperature in experimental 8

9 chamber ( in C/sec) using a chart recorder plugged into the TEMP IN input (alternatively use a stopwatch for timing and visual observation of the YSI 43TD tele-thermometer). 3. Measure the HEATER A output voltage when switched to TEMP 1 (V 1,s-s ) and then the output voltage when switched to TEMP 2 (V 2,s-s ). An initial value for R C is given by R C = {100 - (TEMP 2 - TEMP 1) 2 / [.(V 2,s-s -V 1,s-s )]} % = percent of the full-scale value This gives an initial estimate for R C. From this value the optimum can be set by observing the temperature transient and increasing or decreasing R C. When the rise is too slow R C should be increased and vice versa. TROUBLESHOOTING & HINTS TC-1 doesn't work Usually either the internal or external battery is discharged. If the external battery is charged (ie. reads 12V) then you can check the approximate status of the internal battery using the following procedure. Disconnect the heater and pre-heater. Look directly at the LO BATT indicator and switch the ON switch from the off position to the ON position. If the LO BATT. LED flashes then the internal battery is not completely discharged. If, when you leave the switch in the ON position and the LO BATT LED glows then you must charge the internal battery. If the LO BATT indicator has been on for some time (or the internal battery has only been charged briefly) the TC-1 may behave strangely. Firstly the TEMP 1, 2 controls will not operate. Secondly you will notice that when you switch the TC-1 on the needle on the YSI Telethermometer will move significantly (usually it moves less than 0.5 C). Thirdly the output to HEATER A and B will drop to about 100mV. This behavior indicates that the internal protection circuit has shut down the TC-1 power stage to protect the heaters. When the internal battery is charged normal function will return. If you use the TC-1 for long periods of time such that the internal battery does not charge sufficiently overnight you can increase the charging rate by raising the input voltage to 14V. This will approximately double the charging rate. This higher rate may lead to a shortened internal battery life due to increased heating of the batteries. An option is available which allows continuous use of the TC-1 without charging the internal batteries. Please contact us for details. Which is the true bath temperature, the TC-1 dial or the YSI temp or? The true temperature is given from the calibration for the probe that you are using. and the temperature on the YSI dial A conversion table is supplied with the TH-1 Thermistor probe (a similar table comes with the YSI-511). Take the temperature reading on the YSI-43TD, T-YSI and locate the corresponding T-true temperature on the chart. For the TH-1 the two temperatures should be similar around 35 C. At lower and higher temperatures the deviations are quite large (ie. several C). The dial on the TC-1 corresponds approximately to the dial on the YSI-43TD. It is possible to internally adjust the temperature reference potentiometers in the TC-1 to make the two scales more closely correspond. If you wish to do this please contact us for instructions. The heater LED's don't light This is usually quite normal when the TC-1 is used with the H-1. Only when the temperature is changing (eg. warming from room temperature) will the Heater LEDs glow brightly. The LEDs will also glow when you use the HC-1 or other heaters and larger tissue baths that require more current. Can I use HEATER B as the main heater and HEATER A as a pre-heater? Yes. If you are using a heater that requires more power then use the HEATER B output. This heater output can go to higher voltages. This is important for heaters with higher resistances. Don't use the HEATER B output for the H-1 Heaters as you will probably damage them by overheating. Do I need the hypodermic tubing to protect the thermistor? 9

10 If you place cells on poly-l-lysine or other coated slides they may bump into the thermistor probe and eventually damage the insulation. Suitable tubing can be obtained by scoring regular hypodermic needles and bending them to and fro with pliers. Where does everything go? Most researchers have their own methods for flowing solutions in and out of chambers and use of ground wires etc. Below is a guide for one way to setup the bath. For the inflow use a piece of polyethylene tubing (eg. BD Intramedic # 7410 ID 0.58mm OD 0.965mm) with the end bent at right angles for about 0.1". Place the right angled piece through the narrow slit between the inlet chamber and the main chamber so that the tubing points to the rear of the chamber. Glue the tube in place and seal around the slit between the two chambers with Silicon glue. The idea is to force the solution entering the chamber to mix rather than just flow down a central channel. Join the pre-heater to this tube with a short length of thin silicon tubing (eg. ID 1/32" OD 3/32" # available from Cole Parmer, Chicago IL 60648;ph: ). Keep the distance from the pre-heater to the bath inlet as short as possible (this gives better stability to the temperature control). At the outlet one device that you may wish to try is a fine Teflon tube (#22 lightweight Teflon tubing ID 0.028" Wall 0.006", Small Parts Inc, Miami Lakes, FL , ph: ) with the end bent at right angles. To bend the Teflon tubing use a longer length initially and bend it in half by holding the midpoint against a soldering iron tip. When it has bent sufficiently cut one of the ends so that you have about a 1cm length with a 1mm length at right angles, much like a miniature umbrella. If you use a FL-1 Miniature positioner bend a piece of hypodermic tubing or needle (18 or 19 gauge) so that it is held in the groove of the positioner block and has a right angle piece (about 0.1" long) at one end. You can connect the Teflon tube (long piece) and hypodermic tube (short piece) using silicon tubing described above. You may need to shorten the Teflon tube. It doesn't make sense to use just a long piece of Teflon tubing because it is so flexible that it would bend up and down with the suction. At the other end of the hypodermic tube connect some wider bore Teflon tubing (about 1/16" diam.) for about 3 inches or so. You can join the stainless steel tubing and Teflon tubing with silicon tubing (eg. ID 1/16" OD 1/8" # ; Cole Parmer). The Teflon helps to produce fine droplets rather than a continuous stream. You may find that this Teflon sucker produces high frequency noise which is probably due to static charge being built up on the droplets as they speed through the tubing. If you have very high levels of vacuum you may need to reduce them using a Needle valve (eg. MNV-1 Clippard Instrument Co., 7390 Colerain Road, Cincinnati, OH ph: ). The tapped hole in the front left of the BT-1 is intended to hold a block used to maintain a ground wire in place. A simple block using a thick spacer (about 0.15" thick, 0.3" diam.) can be made of Delrin or Plexiglass. Use a nylon washer and 4-40 screw to hold the ground wire in place. You want to be certain that solution cannot reach the solder joint between the silver wire and wire going back to the amplifier headstage. To prevent solution creeping to the ground wire use a thin barrier made of silicon glue. Cut the nozzle of the tube to give about a 1/16" bore or use a 16 gauge needle. You may also wish to put a barrier around the perimeter of the bath in case you leave the vacuum off while the solution is still flowing in. To help reduce the curvature of the meniscus in the central chamber you may find it helpful to use thin Teflon sheeting made by Dupont Teflon FEP 500 C (Dupont Wilmington, DE 19898, ). This sheeting can be glued on one side and attached to the front and rear edges of the inner chamber. Also, a piece of suitable diameter (about 3/16" diam) Teflon tubing with a groove cut in it matching the path between the central chamber and the outflow chamber can be pressed into the outflow chamber. This helps reduce the curvature of the meniscus in the outflow chamber and helps in the maintenance of a constant solution level. Bath assembly Details of the BT-1 Bath construction are given with the bath. The bath can be held onto the moveable microscope stage using 3 thumbscrews in the three rectangular indents in the bath (see figure below); 2 at the front and one at the rear. If you don't want to tap holes in the moveable stage that comes with the microscope it is usually possible to make a substitute stage one out of 3mm (1/8") Plexiglass. If you do this it may be useful to enlarge the central area of the substitute Plexiglass stage. For testing you can attach the bath to the stage using double sided tape or a similar material. Depending on the stage cutout and lenses you may find it necessary to raise the bath above the stage by about 1mm to provide clearance for the H-1 Heater. This can be done using nylon washers placed between the bath and stage on the shafts of the thumbscrews. 10

11 Thermistor placement When the BT-1 Bath and H-1 Heater are used for a maximum useable area of the bath and FL-1 positioner Pre-heater BT-1 Bath Glass bottom H-1 Heater Bath assembly accurate temperature control the heater should be placed so that the thermistor is on the longer axis of the heater approximately 5mm right of the center of the heater element (see figure below). Although other placements are possible the tapering region of the H-1 Heater element must be avoided as the power output in this area is less than in the central region. Pre-heater assembly The pre-heater is constructed by winding approx. 1 foot of 10Ω/ft resistance wire around an approximately 1.25" length of glass capillary. Details of this are given with the RW-10 Resistance wire. The solution outlet pre-heater should be placed as close as possible to the inlet of the Bath Assembly figure as indicated in the above figure. Thermistor position Thermistor position 11

12 HPRE Pre-heater and HPREC Control box The HPRE Pre-heater and HPREC Control box allows more flexibility in the range of flow rates and provides improved stability of temperature control. The HPRE Pre-heater has a folded loop construction to heat solution over an extended "distance". This provides a slow transition in the temperature profile as solution comes out of the pre-heater which gives more stable temperature control when the sensing thermistor is located away from the outflow of the pre-heater. The HPRE Control box uses the output from a temperature sensor located on the pre-heater to significantly reduce the power to the pre-heater when the flow is halted. This reduces any temperature overshoot when the flow is restarted after being halted. Using HC-1 Heater with TC-1 You should refer to the instructions that come with the HC-1 Heater for detailed guidance on the setup of the HC-1 Heater for use with culture dishes. This section provides information on hooking up the heater to the TC-1 and factors which influence the performance of the TC-1 and HC-1 combination. Electrical connections The HC-1 is normally plugged into the HEATER A. ELECTRICAL CONNECTIONS section. The rest of the cabling is as indicated in the Pre-heater If you intend to flow solutions you should construct a pre-heater as described in the instructions provided with the RW-10 Resistance wire. The HPRE and HPREC combination provide a more flexible pre-heating arrangement when a wide range of flow is to be used. The pre-heater should be positioned as shown in the Mechanical Assembly figure. You should experiment to achieve the most uniform temperature distribution when you are flowing solutions. It my be helpful to provide some kind of baffle in front of the pre-heater outlet or to point the pre-heater towards the rim of the culture dish to help in mixing the inflowing solution. Thermistor position The thermistor should be positioned so that it is just outside the central hole. Placing the thermistor at the center of the culture dish is not a good idea because of the delay in heat diffusing to the probe from the heater. This delay will destabilize the temperature control. You can also experiment with the thermistor position by using the LTX Liquid crystal temperature sensor material to measure the 2D temperature distribution. Tuning procedure You should leave the R p and R c in there shipped positions; R p :80%, R c :50%. Because the heating and cooling of the HC-1 heater setup is much slower than with the H-1 Heater the setting on these controls do not greatly influence the performance of the TC-1. If you are flowing solutions the B GAIN should be set to the minimum value possible such that solution leaving the pre-heater is approximately at the temperature being regulated (ie. setpoint). Making the B GAIN too large will destabilize the control and there will be large oscillations. If you need to flow solutions at more than 1.5ml/min then you should use the HPRE and HPREC combination for pre-heating. 12

13 Thermisor placement 2 glass cover slides thermal grease Pre-heater 30mm culture dish 2 glass cover slides thermal grease Stage insert HC-1 Concentric heater Pre-heater Thermistor probe Central hole in insert Notes on mechanical assembly: 1. See HC-1 Instructions for further details. 2. HC-1 is bonded to bottom of stage insert round glass cover slides improve uniformity of temperature and allow for rim that is present on most plastic culture dishes. The slides are bonded together with optically clear glue. They are either glued to the insert using thermal epoxy or held with thermal grease. 4. The TH-1 Thermistor probe is placed towards the rim of the petri dish as indicated in the diagram. 5. Stage insert should be as small and light as possible and thermally isolated from the microscope stage (using plastic shims or similar thin insulators. 6. Pre-heater is made using a piece of capillary wrapped with RW-10 resistance wire (see separate Pre-heater instructions) 13

14 APPENDIX Additional items needed for the Temperature Control System: 1. YSI-43TD tele-thermometer available from VWR Scientific P.O. Box 999 South Plainfield, NJ ph: V battery or regulated power supply capable of delivering 1.5Amps. Batteries are recommended for electrophysiological studies where minimal electrical interference is essential. Recommended battery and charger :- Panasonic LCR12V17AP (12V 17Amp-hour Gel battery; Part#: available from Allied Electronics ). Automatic Charger PSC A or equiv. (Part#: available from Allied Electronics ) A N. DATYNER 7 December, /4" 1-13/32" 0-3/16" 0-5/16" 2-25/32" 1-21/32" 1/32" Use 1/32" dia. x 3/32 long end mill 3-1/16" 1-29/32" 1-27/32" 0-1/8" Use 1/32" stub end mill Section A-A tap /32" tap /32" B 2" 0-1/4" 0-13/16" 0-1/16" 0-5/16" 1-1/8" 0-1/2" 0-17/32" 0-15/32" 0-3/8" tap 4-40 B 0-3/16" 0-3/8" 1/8" 0-1/16" 0-7/8" 0-7/8" 0-1/4" 0-1/8" 0-1/8" 0-3/16" 0-5/8" 2-7/8" 3-1/16" 2-5/8" 3-1/4" A 0-1/16" 0-3/32" 0-7/32" 1/32" deep groove Plans for BT-1 Bath Section B-B 14