controller compatibility question

[jayarrG7]

Thanks to all who helped out with my question about the Estes E controller.
I am now thinking more along the lines of an aerotech interlock as my first controller.
However, I read somewhere today that an Estes controller should be used with Estes igniters. As my first build in progress is an Estes Big Bertha, I am a bit confused on this subject.
Would the Aerotech interlock be incompatible or require some adaptation to work with the Estes B and C rocket engines?

 

[SCE to AUX]

The Interlock controller will work just fine with Estes igniters.

 

[SteveF]

that is mostly just marketing to make sure you buy all their stuff. If I read it correctly the interlock comes with a clip meant to be used for copperhead igniters that come with a lot of their smaller engines. but you can replace that clip with two microclips like you get with the estes controllers.

 

[shreadvector]

Thanks to all who helped out with my question about the Estes E controller.
I am now thinking more along the lines of an aerotech interlock as my first controller.
However, I read somewhere today that an Estes controller should be used with Estes igniters. As my first build in progress is an Estes Big Bertha, I am a bit confused on this subject.
Would the Aerotech interlock be incompatible or require some adaptation to work with the Estes B and C rocket engines?

Here is what you are really asking and the answer:

"Why is an Estes controller not recommended for other brands of igniters and what is the compatability of various controllers with various igniters?"

A controller must do several things.
* It must comply with NFPA code for safety (have a removeable interlock or "key" and have wires from the controllerr to the pad that are of the specified length for the power level being launched).
* It must be safe to use, so the continuity indicator (lamp or buzzer) must not allow too much current to flow through because some igniters can fire on very low current flows.
* When the spring return launch button is pushed, it must deliver enough current to the igniter to heat it up to ignite the motor or the pyrogen on the tip of the igniter.

Estes controller deliver 200 milli-amps of current throught the continuity lamp. This will fire a Quest Q2G2 igniter, so the Estes controller will work with Quest igniters, but it will not be safe to check continuity. you can solve this by replacing the incandescent lamp with a low current super-bright LED. This reduces the current to 30 milli-amps.

The Estes controller will not be able to deliver a large amount of amps to fire high current igniters such as the Aerotech Copperhead. For those you need a larger power source - usually a 12 volt battery like a small lead acid car, scooter or computer battery or a ni-cad battery pack. The Estes controller will deliver enough amps to quickly heat up and fire their Estes igniters.

The Quest controller will be safe for all igniters when checking continuity because of it's LED and electronics. Firing current will be a bit more than Estes because of the use of a 9 volt alkaline battery and the slightly thicker wires to the pad. If you use the External Battery Connector (EBC), then you can use a 6 volt lantern battery or a 12 volt battery and fire any igniter known, while still being continuity safe.

The Aerotech interlock controller will be continuity safe (electronic buzzer and no lamp) and will fire any igniter known and it has long thick wires to the pad. Make sure you have micro clips for non-Copperhead igniters.

The Estes E controller is undergoing testing with an LED for possible production incorporation. It has longer thicker wires and will deliver more amps to the pad from the 4 AA alkaline batteries than the regular Estes controller with the shorter thinner wires. It can ignite clusters of 2 Estes igniters or a large number of Quest Q2G2 igniters, but will not fire Copperheads unless you bypass the battery compartment and use a more powerful battery.

 

[eggplant]

Thanks to all who helped out with my question about the Estes E controller.
I am now thinking more along the lines of an aerotech interlock as my first controller.
However, I read somewhere today that an Estes controller should be used with Estes igniters. As my first build in progress is an Estes Big Bertha, I am a bit confused on this subject.
Would the Aerotech interlock be incompatible or require some adaptation to work with the Estes B and C rocket engines?

The interlock is kind of expensive. You could look into the pratt hobbies GO-Box, or, if you enjoy electronics, you could make your own, like I am right now. I spent about $30.00 at radioshack, including two 6 volt batteries to wire together and make one 12 volt. It is all contained in an old toolbox, and looks pretty slick. If you really want the interlock, there is no reason that it wouldn't work, you just need to remember to buy some batteries... :wink:

 

[bobkrech]

Several important design features for a reliable launch controller.

Removable safety interlock that prevents power from going to the firing circuit.

• This does not need to be a key switch. It can simply be a shorting plug.

Low current continuity check.

• An led circuit that draws not more than 30 ma should be safe for virtually igniters.
• 470 ohm or higher resistor in series with led in a 12 volt system.

Zip cord/speaker wire/extension cord clip leads longer than the personal separation distance for the motor impulse class requirement

• D and lower - 15' minimum - 18 gauge
• E-G - 30' minimum - 16 gauge recommended
• L1 - 100' minimum - 14 gauge recommended

A battery that can deliver more than 20 amps to the igniter clips.

• Lowest cost solution is any 12 volt gel cell with > 2 AH capacity
  • They can be recharged from a power port in you car
  • A 7 AH gel cell battery will launch several hundred rockets
• 6 volt lantern batteries are marginal with a 3 motor cluster using Estes igniter and won't be reliable with an AT Copperhead and they are expensive
• Rechargeable NiHM and LiPo RC battery packs work well but require special chargers

Bob

 

[MarkII]

The interlock is kind of expensive. You could look into the pratt hobbies GO-Box, or, if you enjoy electronics, you could make your own, like I am right now. I spent about $30.00 at radioshack, including two 6 volt batteries to wire together and make one 12 volt. It is all contained in an old toolbox, and looks pretty slick. If you really want the interlock, there is no reason that it wouldn't work, you just need to remember to buy some batteries... :wink:

I have often mentioned Pratt Hobbies products because they seem to be well thought out and well-made. But here's a direct price comparison:

Pratt Hobbies Go Box: $39.95
AeroTech Interlock Controller: $42.90
Price difference: $2.95 (IOW, not a dramatic difference)

Other choices:
Heavenly Hobbies LightSword: $38.99
Mercury Engineering Igniter Lighter: $46.00
Sunward 12 Volt Rocket Launch Controller: $99.00

As Bob mentioned, a 12 volt gel cell battery is your best bet for power. It has far more capacity than a pair of lantern batteries that have been wired together.