Sunday, May 6, 2012

Spektrum TM1000 telemetry voltage probe installation

I recently upgraded from a Spektrum DX6i to a DX8. Among the new features is telemetry- and the new radio came with a TM1000 telemetry module, a temperature probe, and a voltage probe. For me, the main advantage is to be able to set a low voltage alarm so you can fly out the entire flight pack. This is really helpful when you might be using a range of battery capacities- on my Parkzone Icon A5 I use everything from a 1300 mAh to a 2200 mAh, which makes using a simple timer useless.

The temperature probe doesn't need any real installation- just plug it in and attach the sensor to whatever you want to measure, so very quick and easy. The voltage probe does need to be hard wired into the aircraft's electrical system. I decided to make a removable wiring harness so I could easily move the TM1000 and voltage probe from aircraft to aircraft.

Making a custom harness is very easy for anyone who is capable of soldering their own EC3 connectors.

Voltage Probe, as from Spektrum

Step 1: Cutting the wires

Wires, cut to length
I used Turnigy 14 gage wire. Choose your wire according to expected current draw. I cut the wires to 2" in length. Shorter is probably better for fitting in your airplane, but it gets more difficult to solder and attach the connectors. If I were to do it again, I might try 1" pieces.

 Step 2: Trim the insulation

Roll cutting
I like using a roll cutting technique. Use a razor blade or X-acto knife and gently press into the wire insulation while rolling the wire. Take care not to press too hard or you'll cut through wire strands. You could also use a wire stripper, but for small trims like this I find the roll cutting technique to be easier and more convenient. For these connectors I chose to remove 1/8" of insulation from each end of the wires.

Insulation trimmed

Step 3: Soldering the connectors

Set up in 3rd Hand Tool
You'll have to choose which end of the wiring harness you want your sensing wires to go. It doesn't matter if it's the battery end or the ESC end. Just take care to make sure your polarities are all correct, if they aren't you can easily fry your ESC, TM1000, battery, etc.
A third hand tool really comes in handy here. It's a bit tricky to solder both the power wire and the sensing wire into the connector at the same time. In the photo above you can see both wires inserted into the connector before soldering. I like to hold the soldering iron on the outside of the connector, wait for everything to get hot enough, then feed the solder into the joint. It also helps to put a bit of soldering flux on the wire tips.

Finished connector
  Once the connector is soldered, press it into the EC3 plastic body. There are plenty of online videos / guides elsewhere to show how to do this in detail. Repeat for both wires.

Harness with one end complete
Before I attached the connector to the other end, I chose to put a bit of heat shrink to act as a strain relief.

Completed harness, ready for installation

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