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Thermometer
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Dual Channel Schmitt Triggered Coolant Temperature Controller.

This controller is designed to work with standard Thermistor Temperature Sensors found in Cars and Trucks.
Each unit is hand built, tested and setup to ensure premium quality and durability.

It operates at the standard Vehicle DC Voltage of 12V.
Stand-By "OFF" condition current =10mA
Each circuit accuracy 1o Celsius (external Sensor dependent)
Die Cast Casing Size: 11cm x 6cm x 3cm

The System has 2 sets of circuits which can receive signals from 2 independent Thermistor Sensors with adjustable 'ON' (Hot temperature reached) condition where the output turns on the Cooling Fan Relay(s).

Unlike most switching systems - not only does each circuit adjust to a "Hot" 'ON' (say 90o C) condition - they also have adjustable 'OFF' circuitry which maintains the Fan Relay 'ON' condition until a pre-determined lower temperature (Say 85o C) is achieved. By this mechanism you are able to maintain a more stable engine temperature if desired and a more consistent drive to the Fan.

Once the lower temperature has been achieved and the Cooling Fan has switched 'OFF' the system goes into Stand-By mode awaiting the Thermistor Sensor to send the "Hot" (90o C) signal again.

2 independent adjustable sensing and switching circuits are included in the same package thus allowing full control of say engine Cooling Water Radiator and Cooling Oil Radiator temperatures.

You can also connect one Thermistor Sensor to both inputs thus providing independent temperature control for 2 separate Cooling Fans should you so desire.

Logic Drawing

Temperature to Resistance Thermistor Values Vehicle Temperature Sensors

The chart to the left indicates the changes in Resistance that a standard Vehicle Temperature Sensor (Thermistor) presents via its' +VE output pin (relative to EARTH / GROUND).

As you can see - when the Sensor is at around room temperature the resistance presented is about 2500 Ohms.

The difference between 90o Celsius and 85o Celsius is very small (in Resistance Values).

Therefore a very sensitive circuit is required to differentiate between the 2 temperatures.

The ReelAudio Controller employs Operational Amplifiers, Schmitt Trigger chips and protected Relay drive components to ensure that operation is constant between minute differences sent by the Thermistor.

2 versions of the controller are available.

A Single Channel Dual Temperature Controller (running a single Fan) and the Two Channel Dual Temperature Controller running 2 independant Fan systems.

Single Fan Drive

Dual Fan Drive

Terminal Connections of the Box to/from the Vehicle are Coded the same for both units. These connections are also marked on the top of the box.

Terminal 1 = +12Volt (Input to the Box)
Terminal 2 = Ground/Earth
Terminal 3 = Sensor No 1 (Input to Box)
Terminal 4 = No 1 Fan Relay +V (Output from the Box)
2 x Fan Control Unit only
Terminal 5 = Sensor No 2 (Input to Box)
Terminal 6 = No 2 Fan Relay +V (Output from the Box)



Single Channel Dual Temperature Controller

Single Channel Dual Temperature Controller

Single Channel Dual Temperature Controller

2 Channel Dual Temperature Controller

2 Channel Dual Temperature Controller

2 Channel Dual Temperature Controller


Connections to Vehicle

Both the single Fan and the 2 x Fan systems have interconnections via custom inbuilt plug/socket screw terminal connectors.
Each circuit board is housed in a Die Cast Heavy Duty casing (11cm x 6cm x 30cm).

The terminations to each box are shown on the lid:

Connections
Connections

Both circuits of the Controller are pre-set to operate at 90oC "ON" and 85oC "OFF".

If you need to change these settings then locate the 2 or 4 controlling 20 turn multi-turn RV potentiometers inside the unit and turn these all counter clockwise (at least 20 turns each) to set everything to minimum. DO THIS PRIOR TO CONNECTING THE UNIT TO THE VEHICLE.

As the circuitry draws only 10mA in Stand-By Mode you can connect the +12v and ground (Power-In) permanently to the Vehicle Battery [thus allowing the unit to drive the Fan(s) whilst the ignition is "OFF"]. This small current drain is negligible to the comparatively huge Battery Life of the Vehicle (unless it is standing idle for a month or more).

If you decide to connect the +12V through the ignition switch then of course, the Cooling System will turn "ON" and "OFF" with the ignition switch.

Although the internal circuit board Relay Switches are capable of delivering >10amps, the circuit boards are fitted with a 1 Amp Quick Blow fuse to protect the circuitry. Thus it is essential to use an appropriate additional proprietary switching Relay for each Cooling Fan otherwise the controller protection fuse will blow.

The coil connections of a standard vehicle Fan Relay needs less than 500mA to make the switching work - so the 1 Amp quick Blow fuse on the circuit Board is perfectly adequate.

DO NOT USE A FUSE GREATER THAN 1 AMP QUICK BLOW ON THE CIRCUIT BOARD!


You may change the pre-set temperature settings by adjusting the RV controls as follows:

Sensing / Switching Circuit 1
Connect the No 1 Sensor terminal (3) to the + output of the Radiator Temperature Sensor (Thermistor).
Connect the No 1 Fan Relay +V terminal (4) to the +V input of the Fan switching Relay.

If you need to change the pre-set temperature settings (90oC "ON" and 85oC "OFF") then turn RV11 and RV12 counter clockwise at least 20 full turns.

Run the vehicle and monitor the Temperature Gauge (if fitted).

Adjusting Pots RV11 and RV12
Once the engine has reached the desired temperature, adjust RV11 clockwise until the RED LED (near Relay 1) turns ON.

The Vehicle's cooling Fan should now be "ON".

Adjust RV11 backwards slightly to ensure an accurate "Turn ON" position is achieved.

Once RV11 has been set, adjust RV12 clockwise so that the BLUE LED turns on too. You may want to turn RV12 another 2 full turns after the Blue LED has turned on. This will ensure that the secondary circuit will not turn "OFF" until the temperature has dropped lower than the initial "HOT" 'Turn ON' condition.

Whilst the Cooling Fan is "ON" the engine temperature will start to drop. RV11 controls the "TURN ON" Temperature and RV12 adjusts the "TURN OFF" condition.

If you monitor the temperature on the gauge - once the required lower temperature has been achieved turn RV12 anticlockwise slowly until the BLUE LED (and the main Cooling Fan) turns "OFF".

The RV potentiometers are multi-turn devices. It should be relatively easy to achieve accurate "Turn ON" and "Turn OFF" conditions with slight adjustments to these controlling potentiometers.

If, while adjusting RV12, you turn that potentiometer backwards too far the whole circuit will turn "OFF" (as the engine temperature cools) - going into Stand-By mode and will not turn "ON" again until the pre-set "HOT" condition of the Coolant is once again achieved.

Sensing / Switching Circuit 2

Connect the No 2 Sensor terminal (5) to the + output of the 2nd Radiator Temperature Sensor (Thermistor).
Connect the No 2 Fan Relay +V terminal (6) to the +V input of the 2nd Fan switching Relay.

If you need to change the pre-set temperature settings (90oC "ON" and 85oC "OFF") then turn RV21 and RV22 counter clockwise at least 20 full turns.

Run the vehicle and monitor the Temperature Gauge (if fitted).

Adjusting Pots RV21 and RV22
Once the engine has reached the desired temperature, adjust RV21 clockwise until the RED LED (near Relay 2) turns ON.

The Vehicle's 2nd cooling Fan should now be "ON".

Adjust RV21 backwards slightly to ensure an accurate "Turn ON" position is achieved.

Once RV21 has been set, adjust RV22 clockwise so that the BLUE LED turns on too. You may want to turn RV22 another 2 full turns after the Blue LED has turned on. This will ensure that the secondary 2nd circuit will not turn "OFF" until the temperature has dropped lower than the initial "HOT" 'Turn ON' condition.

Whilst the Cooling Fan is "ON" the engine temperature will start to drop. RV21 controls the "TURN ON" Temperature and RV12 adjusts the "TURN OFF" condition.

If you monitor the temperature on the gauge - once the required lower temperature has been achieved turn RV22 anticlockwise slowly until the 2nd BLUE LED (and the 2nd Cooling Fan) turns "OFF".

The RV potentiometers are multi-turn devices. It should be relatively easy to achieve accurate "Turn ON" and "Turn OFF" conditions with slight adjustments to these controlling potentiometers.

If, while adjusting RV22, you turn that potentiometer backwards too far the whole circuit will turn "OFF" (as the engine temperature cools) - going into Stand-By mode and will not turn "ON" again until the pre-set "HOT" condition of the Coolant is once again achieved.

Setup with No Temperature Gauge

You will need an accurate digital multi-meter set to OHMS (2k position [or maybe 20k dependent to the cold resistance of the sender]).

Disconnect the Thermistor +VE Connection and measure across the +VE terminal and GROUND/EARTH. Use the Temperature Chart shown to measure the OHMS emitted by the Sender. You will see the OHMS reading drop as the temperature rises. Decide what will be the measurements required before you start.
NOTE: Use the chart as a guide only. Some senders will measure slightly differently to those shown.

This method might be easier if you install a temporary single pole double throw switch to enable quick measurement and re-connection of the Control Box. It should be wired as shown below:

Wiring in the Digital Meter

Temperature to Resistance Thermistor Values
For example:

When the radiator coolant is at 90o C the Sender should read around 241 OHMS.

When the radiator coolant is at 85o C the Sender should read around 291 OHMS.

Quickly re-connect the Sender wire to the control box and adjust the VR control for the condition you want.

Once all controls are set then install the casing lid and site the control box to the side of the engine compartment. Tie-wraps (not supplied) will allow you to affix the box to a suitable bulk head.

Site the Control Box away from Direct Heat and Water!




Q & A:

Can you use the existing vehicle thermistor sensors?
a. The tollerances of adjustment within the system will allow you to use old and new working thermistors - so no need to worry about installing additional sensors.

Can I run the system through the ignition switch or direct from the Battery connections?
a. Either is possible. The system will not "forget" its' settings if you wire it through the ignition switch. If you wire directly to the battery connections then it is possible to have the unit running (to cool the engine further) even though the ignition is off. The stand-by current drawn by the box (when everything is off) is only 10mA - so it can be wired directly to the battery without fear of draining the battery too much.

You seem to have put up the same photo for the circuit diagram on both units for sale (2x Fan and the Single Fan model). Does it actually reflect the Dual system?
a. Both units for sale are Dual Temperature models ie: you can adjust for the "on" Temperature and adjust the "off" Temperature too. The single Fan model is the same board as the twin Fan with less components.

1) Your circuit diagram shows 2 separate thermistors, but can the same thermistor/sensor be used to switch the fan on and off?
a. A single Thermistor can be used to switch a 2 x Fan model - the fans being controlled by their independent circuits ie: same Thermistor - different "on" and "off" temperatures - (one fan working harder than the other etc).

2) Can I use the standard Smiths/Lucas temperature senders that are used for my Smiths temp guages? Or do I need some special kind of thermistor/sensor?
a. The standard car temperature senders can be used.

3) Where are the controls for setting up /adjusting the temperature you want to switch on, or off? I can't see them anywhere in your photos. Are they inside the box?
a. The temperature controlling potentiometers are inside the box.

4) How do I calibrate the adjustment controls? Is there a display showing the voltage, or resistance or temperature? or do I have to put an autometer across some terminals and set it up that way?
a. The instruction sheets with each module describe how to setup without temperature gauges (using an Avo Meter).

5) Is there any guarantee?
a. Each unit has a 1 year guarantee to operate correctly & accurately.

a. You are right John, a lot of time and effort has gone into the design and testing of this unique product - The latest models are in use today and have proved their capabilities cooling hybrid V8 engines to exacting degrees of accuracy.


Warranty:

The Control Box and its' contents are guaranteed for a period of 12 months from the date of purchase.
Normal Usage is implied by the word 'Guarantee' and 'Warranty'.

Click Here to view the Products & Pricing Page.

All Warranty repairs are undertaken on a return to base principle.
Any carriage costs are the responsibility of the Client

REELAUDIO MAKES NO WARRANTY, EITHER EXPRESS OR IMPLIED WITH RESPECT TO ANY PRODUCT, AND SPECIFICALLY DISCLAIMS ALL OTHER WARRANTIES, INCLUDING, WITHOUT LIMITATION, WARRANTIES FOR MERCHANTABILITY, NON-INFRINGEMENT AND FITNESS FOR ANY PARTICULAR PURPOSE. REELAUDIOS' SOLE OBLIGATION AND LIABILITY FOR PRODUCT DEFECTS SHALL BE, AT REELAUDIOS' OPTION, TO REPLACE SUCH DEFECTIVE PRODUCT OR REFUND TO BUYER THE AMOUNT PAID BY BUYER THEREFOR. IN NO EVENT SHALL REELAUDIOS' LIABILITY EXCEED THE BUYER'S PURCHASE PRICE. THE FOREGOING REMEDY SHALL BE SUBJECT TO BUYER'S WRITTEN NOTIFICATION OF DEFECT AND RETURN OF THE DEFECTIVE PRODUCT WITHIN NINETY (90) DAYS OF PURCHASE. THE FOREGOING REMEDY DOES NOT APPLY TO PRODUCTS THAT HAVE BEEN SUBJECTED TO MISUSE (INCLUDING WITHOUT LIMITATION STATIC DISCHARGE), NEGLECT, ACCIDENT OR MODIFICATION, OR TO PRODUCTS THAT HAVE BEEN SOLDERED OR ALTERED DURING ASSEMBLY, OR ARE OTHERWISE NOT CAPABLE OF BEING TESTED, OR IF DAMAGE OCCURS AS A RESULT OF THE FAILURE OF BUYER TO FOLLOW SPECIFIC INSTRUCTIONS.

IN NO EVENT SHALL REELAUDIO BE LIABLE TO THE BUYER OR TO ANY THIRD PARTY FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, PUNITIVE OR EXEMPLARY DAMAGES (INCLUDING WITHOUT LIMITATION LOST PROFITS, LOST SAVINGS, OR LOSS OF BUSINESS OPPORTUNITY) ARISING OUT OF OR RELATING TO ANY PRODUCT OR SERVICE PROVIDED OR TO BE PROVIDED BY REELAUDIO OR THE USE OR INABILITY TO USE THE SAME, EVEN IF REELAUDIO HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

Units are Designed and Hand Built by:
Paul Baldwin
www.ReelAudio.Co.UK
BaldwinHiFi.Co.UK
12 Tack Lee Road
Yapton
Arundel
West Sussex
BN18 0HB - UK - Great Britain
Direct EMAIL: neverfinished0@hotmail.com
Tel: 01243 553231 - Mobile: 07858 089421
Paul will be unavailable from 27th June 2017 (for 10 days) while installing wiring and equipment into a new HiFi Venue in Ibiza
Please note: Paul may be contacted by telephone during his preferred admin period of between 5pm and 8pm. Thankyou.

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