iddhm-m user's manual rev5

8/6/2019 iDDHM-M User's Manual Rev5

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Users Manual

for the

Astro-Smart

Integrated Differential Dew Heater

Module (Model iDDHM-M)

Copyright July 2010


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Astro-Smart LLC P.O. Box 33753 Indialantic, FL 32903Page 1

Users Manual

for the

Astro-Smart



Contents

A. Overview................................................................................................................ 2

B. Contents Included ................................................................................................. 3C. Specifications ......................................................................................................... 3D. Design Features ..................................................................................................... 4E. Basic Functionality ................................................................................................ 4F. How to Use ............................................................................................................ 6

1. Power Cable Routing ...................................................................................... 62. Installation ...................................................................................................... 83. Front Panel .................................................................................................... 174. Operation ....................................................................................................... 19

G. Accessories ........................................................................................................... 20


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Providing the Astronomical Community withPremier Products, Services, and Training

astro-smart.com July 2010

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A.Overview Astro-Smart LLC is the innovatorof this elegant solution to your dewproblem. We incorporate theiDDHM into the fork arm of thevery telescope you are using. Most

users of the LX200 GPS/R/ACFand RCX400 don't use the batterycompartment to run theirtelescope. Our unique approachoffers a clean and efficient use ofthis space to bring the dew control you need. We utilize the wastedspace of your telescope tominimize loading and wireclustering to provide a completereplacement solution to theexisting battery compartment and cover. The iDDHM allows your investment to be brought back to its original condition without alteration in the event you need tosend your scope back to the manufacturer or want to sell in the future.

The Astro-Smart integrated Differential Dew Heater Module (iDDHM) is currentlyoffered for Meade LX200 GPS/R/ACF and RCX400 telescopes. The iDDHM-M wasdesigned with the same Astro-Smart USER-Friendly design philosophy as all ourother products:

-Usable-Serviceable-Elegant-Reliable

...USER-Friendly

It is this integrated module that incorporates a four port heater capability controlledby two channels using two remote temperature sensors (one optional). It will workwith one remote temperature sensor or with a second remote sensor (availableseparately) making your corrector dew control independent from your eyepiece orguidescope dew control for instance.

Figure 1: Integrated Differential Dew

Heater (iDDHM-M)


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B. Contents Included1. User Manual for iDDHM.2. iDDHM Module3. Power cable with white 2-pin circuit board connector and the 2.5mm DC power

connector.

4. Remote Sensor

C. SpecificationsThe iDDHM requires the following: 12 Volts at 3 amps minimum

Note: This current drawn through the iDDHM is dependent on the resistance ofeach dew strap being used with the iDDHM. The total current for all thedew straps must not exceed the power supply current rating.

Center: positive voltage, sleeve: ground [See Figure 2].

Figure 2 DC power plug

Uses dew straps manufactured by other astronomical vendors.

Positive (+) 12V

Grounded Sleeve

The total resistance of all the dew heater straps used with the

iDDHM must follow this equation for SAFE operation:

Current Rating of Power Supply 1 1 1 1= + + +

Voltage output of Power Supply Rstrap 1 Rstrap 2 Rstrap 3 Rstrap 4

Astro-Smart LLC assumes no responsibility

if this or any other warning is not heeded.


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Page 4

D.Design FeaturesThe Astro-Smart integrated Differential Dew Heater Module, iDDHM-M, has theseinnovative and unique features:

Efficient and elegant use of the internal space of your telescope. This minimizesthe cumbersome use and Buck Rogers/Octopus look of your setup.

It is lightweight. Yet aids balancing when used in the east fork arm. High quality components and construction. Astro-Smart uses only the best

quality components. It can keep optical surfaces free of moisture in many different circumstances. High quality design employs multi-layer circuit boards with conformal coatings.

E.Basic FunctionalityThe user simply adjusts the temperature differential based on local current ambientand dew temperature conditions. In clear and bright view, the iDDHM-M displaysthe above ambient temperature differential setting via a bar graph showing eachdegree Celsius temperature difference. The display is also calibrated for Fahrenheitdegrees as well. Each iDDHM comes with one remote sensor. You simply co-locatethe sensor head with your primary heater.

Figure 3 displays the normal LX200 GPS/R/ACF or RCX400 battery compartment,the installed 4 port controller (Model iDDHM-M), the circuit board, and a closer

view of the Temperature Scale.


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Figure 3 Views of the iDDHM


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F.How to Use1.Power Cable Routing

The iDDHM is powered through the provided 12V 2.5mm DC power plug. This plugcan be routed in any way that is convenient to the user.

A.

One option (Option A) is to run the power wire through the front of the iDDHM,to the front panel area, and then along the telescope power cable [See Figure 4].This is a simple direct approach that keeps all your power cables bundled. Youcan simply use Velcro or other fasteners to keep the cables together.

Figure 4 Power cable routing Option A

Before installing the iDDHM into your telescope read this

section to determine how you will route your power cable.


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B. Another option (Option B) for power cable routing is through the back of theiDDHM, through the fork arm, into and through the fork arms lower plastic

cover [See Figure 5]. This is a little more tricky to accomplish, but requires nomodification to your telescope. This option allows the power cable to be routednear the main telescope rotating area, yet still allows the iDDHM and telescopepower cables to be bundled together as mentioned with the first option above.

Figure 5Power cable routing Option B

C. The cleanest power cable routing solution (Option C) requires modification toyour telescope and may void your warranty. Because of this it is not presentedhere, you can find this procedure at various URLs on the web. Briefly, it involvesconverting the telescopes existing internal battery compartment wires along witha 2.5mm DC power plug mounted to the telescopes bottom plate. This allowscomplete pass-through and least amount of potential cable wrap. Again, Astro-Smart does not provide instructions for this as it may void your warranty. For afee Astro-Smart will perform this modification for you. Please contact us fordetails.


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2. InstallationThe following steps when followed will allow you to install the iDDHM into yourtelescope safely and properly.

1. Read this User Manual entirely before proceeding.

2. Determine how you will route your power cable.

3. Select the fork arm into which you wish to place the iDDHM.

4. Remove the appropriate form arm battery cover.

5. Unpack the iDDHM from the box.6. Route the iDDHM power cable.

a. If you are routing through the front panel (Option A)then Go To Step 7 on Page 9.

b. If you are routing through the fork arm (Option B)then Go To Step 8 on Page 11.

Store the battery cover that you removed in a safe place so that you can

return the telescope to its original configuration if you wish to in the future.

See Section 1 before proceeding.

Read this User Manual before proceeding any further.

You may wish to select the east fork arm to aid in slightly preloading the

Right Ascension (RA) gear with the small weight that the iDDHM will

provide.


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Page 9

7. Routing power cable through the front panel:a. IF you are routing the power cable through the front of the iDDHM

Module then connect the white connector end of the power cable to the

circuit board observing the correct orientation (The white connector is

designed to fit only one way.) [See Figure 6.]

Figure 6 Connecting Power Cable to circuit board

WARNINIG: BE CAUTIOUS do not force the white connector

onto the circuit board the wrong way. Astro-Smart is not

responsible for failure to heed this warning.


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Page 10

b. As you proceed with Step c carefully route the power cable so it will fitunder the iDDHM Module cover. [See Figure 7.]

c. Continue to route the power cable along with other cables as desired.

Figure 7 Routing power cable through iDDHM front panel

d. Continue with Step 9 on Page 14 .

You may want to consider using Velcro wraps or other plastic cable routers

that have an adhesive back.


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Page 11

8. Routing power cable through the fork arm:a. Loosen the hex (allen) set-screw(s) which retain the plastic fork arm

bottom located on the sides of the metal fork arms.

b. Find a convenient gap between the plastic fork arm bottom and the metalfork arm [See Figure 8].

Figure 8 Example gap location for power cable exit

This will be the exit point of the power cable from the fork arm.


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Page 12

c. Loosen the hex screw of the fork arm [See Figure 9].

Figure 9 Loosening the hex screw of the fork arm.

d. Remove the plastic fork arm bottom by sliding outward [See Figure 10].

Figure 10 Removal of plastic fork arm bottom


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e. Route the power cable through one of the two rectangular cutouts (holes)found in the bottom of the fork arm [See Figure 11].

Figure 11 Routing power cable though rectangular cutout

f. Feed power cable through the plastic battery compartment housing.g. Pull the power cable through enough to provide you with sufficient cable

to connect the white connector to the circuit board [See Figure 12].

Figure 12 Power cable through battery compartment


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13.Connect any dew straps that you have [See Figure 16, Page 17, item (B and F)].

14.Install the Remote Sensor at each location under the dew strap with the flat faceof the sensor facing the telescope piece [See Figure 14].

Figure 14 Remote Sensor Placement

If you purchased the Right-Angle dew strap connector(s) you may choose to

install them at this time along with the connection of your dew straps.

If you purchased the 2ndRemote Sensor you may choose to install it at

this time also.

WARNINIG: Ensure the total resistance meets the specifications

provided in Section C on Page3. Astro-Smart is not responsible

for failure to heed this warning.


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15.Route the Remote Sensor(s) cables along with the dew strap cables. A convenientway to do this is to braid the two cables together [See Figure 15].

Figure 15 Route Sensor cable with Dew Strap cable

16.Connect the power supply that is 12V 3amp (minimum) [See Section C, Page 3].

If you have two Remote Sensors route one with the dew strap that is used for

your telescopes front corrector. Route the second Remote Sensor cable along

with either the dew strap that is used for your eyepieces or your finderscope.


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3. Front PanelThe front panel contains all the controls the user requires [See Figure 16].

.

Figure 16 Front Panel Layout

A. Channel OnLED Indicator

B. Channel 1 DewStrap Plug

C. RemoteSensors Plugs

D. Power Switch

E. TemperatureDifferential Scales

F. Channel 2 DewStrap Plug

H.AmbientTemperatureSensor

I. TemperatureDifferential

Setting Knob

G. TemperatureDifferential LED

Bar Graph


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The following are descriptions of each of the major control panel features:

A. Channel-ON LED Indicators: Each of the two dew heater channels has a separateindicator. When the respective Channel is powered (ON) by the iDDHM circuitthe appropriate red LED will illuminate. This indicates power is being supplied tothe dew straps that are plugged into the respective Channel Dew Strap Plug.

B. Channel 1 Dew Strap Plug: These two plugs provide power to the two dew straps when they are plugged into them. When the Channel-1 On LED Indicatorilluminates then there is power supplied to these Channel-1 Dew Strap Plugs.They are standard RCA plugs. Any standard dew strap from astronomicalvendors will work with the iDDHM.

C. Remote Sensor Plugs: The Remote Temperature Sensors are plugged in here. TheiDDHM comes with one Remote Temperature Sensor. It can be plugged into

either Remote Sensor Plug and provide temperature information to bothChannels. If the 2nd Remote Temperature Sensor Accessory is purchased andutilized then each Channel will have its own remote sensor.

D. Power Switch: The Power Switch is the main on-off switch for the iDDHM. In theON position the Power Switchs internal LED illuminates indicating power isbeing supplied to the iDDHM.

E. Temperature Differential Scales: There are two Temperature Differential Scalesprovided on the front panel. The Temperature Differential Setting is indicatedwith the Temperature Differential LED Bar Graph (G). The left Scale is in Celsiusand the right Scale is in Fahrenheit. The Celsius graduates from 0 to 10 degreesevery degree. The Fahrenheit Scale is converted and rounded for each Celsius

scale.F. Channel 2 Dew Strap Plug: See B. above.G. Temperature Differential LED Bar Graph: This 10 LED bar graph indicates the

desired Temperature Differential Setting between the Ambient (H) andRemote (C) Temperature Sensors. Each LED in the bar graph indicates 1 degreeCelsius temperature difference set between the two sensors.

H. Ambient Temperature Sensor: This sensor is mounted internal to the iDDHMand is visible on the front panel. It senses the ambient temperature for use by theiDDHM to determine the temperature difference between it and the remotesensors.

I. Temperature Differential Setting Knob: This knob allows the user to set thetemperature difference that they wish to use for the activation of power to thedew straps. Turn the knob fully counter-clockwise for no temperature differentialand fully clock-wise for maximum 10 degree Celsius temperature differential.Both Channels use the same setting that is made with this knob. TheTemperature Differential LED Bar Graph indicates the setting the user has setwith this knob. Each degree Celsius is indicted by an LED on the TemperatureDifferential LED Bar Graph.


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4. OperationOnce the iDDHM, Remote Sensor cable(s), and dew strap cables have been installedaccording to the procedures in Section 2 starting on Page 8, turn the iDDHM ONusing the Power Switch (D). When the iDDHM is turned on you will see the PowerSwitch red LED illuminate. This is the indication that power is being supplied to theiDDHM circuit and is ready for use. You may see other LEDs lit at this timedepending on the setting of the Temperature Differential Setting Knob (I).

Check the weather conditions for your observing site. Note the temperaturedifference between the ambient temperature and the dew point. If the temperaturedifference is relatively small, on the order of 5 degrees Fahrenheit or less, you shouldset the Temperature Difference Setting Knob (I) such that the Temperature

Differential LED Bar Graph (G) indicate a setting on the appropriate TemperatureDifferential Scale (E) that is at least 2 degrees Fahrenheit. The TemperatureDifferential LED Bar Graph (G) is a visual indicator of the temperature differentialsetting the user has set with the Temperature Differential Setting Knob (I).

Power is supplied to a Channel(s) when the temperature difference between theRemote Sensor(s) (C) and the Ambient Sensor (H) is greater than the setting of theTemperature Difference Setting Knob (I) indicated by the Temperature DifferentialLED Bar Graph (G).

You may notice when the Temperature Differential Setting Knob (I) is turned

clockwise a small amount from the minimum setting that the Channel ONLED(s) (A) will illuminate but the Temperature Differential LED Bar Graph (G) willnot be illuminated. This condition indicates a Temperature Differential Setting of0.5 degrees Celsius. All other Temperature Differential Settings are indicated in1 degree Celsius increments.

When only one Remote Temperature Sensor (C) is used, both Channels arecontrolled by that sensor. A single Remote Temperature Sensor (C) can be pluggedinto either Channels Remote Sensor Plug (C). When two Remote TemperatureSensors (C) are used, then each sensor controls the Channel into which it is plugged.

When a Channels Remote Sensor (C) temperature falls below the sum of theAmbient Sensor (H) temperature plus the Temperature Differential Setting (G), thenthe iDDHM will supply power to the applicable associated Channels Dew StrapPlugs (B). The Channel ON LED (A) will illuminate ON as the iDDHM heats theoptical elements and OFF as the optical elements heat above the sum of the AmbientSensor (H) temperature plus the Temperature Differential Setting (G).


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G.AccessoriesYou may use a power supply you already have that meets the specifications listedabove, or you may purchase one from Astro-Smart. Our power supplies provide 12vat 3.3amps and will provide years of dependable service along side your iDDHM.

An optional second remote sensor is available (2RSiDDHM-M) [See Figure 17]. This2nd Remote Sensor allows you to control the heating of separate optical elements.For instance, one remote sensor would be placed with your heater at the corrector. Asecond sensor could be placed at your eyepiece or finder scope objective lens. In thissetup each pair of heaters is controlled by their respective sensor. This allows greatercontrol for the user. This item can be purchased at the same time as you purchaseyour iDDHM-M or at a later time. If you only use the included remote sensor, then

all four heater connectors are controlled by the one sensor; and it can be pluggedinto either remote sensor jack.

Figure 17 Remote Sensor accessory

Another convenient accessory that Astro-Smart offers is a right angle heaterconnector (RACiDDHM-M) [See Figure 18]. This allows your heater to be connectedto the iDDHM-M at a right angle. This may be convenient for you to alleviate anybending that you have of your heater connector and wire.

Figure 18 Right Angle dew strap connector

Please note that when purchasing the Astro-Smart integrated Differential DewHeater Module (iDDHM-M), you can use the heater straps you may already have.

Visit Astro-Smart for more astronomical products,services, and training at www.astro-smart.com .

iddhm-m user's manual rev5

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