Building model rocket controller

Thread Starter

medic2891

Joined May 7, 2018
8
Hi all my name is Eddie i am new to model rocketry and I am building my own controller I have several questions here is a picture of the outside of
controller.
I am using 2 12 volt latern batteries should i connect the in series or parallel ?
next I want to include a test option
i have a speaker output in the rear of box going out to padP_20180507_031810.jpg
here is a picture of my project so far
 

ericgibbs

Joined Jan 29, 2010
13,833
OK,
Could you describe what you are trying to do with the project, any extra information will make it easier to help you.
E
 

Thread Starter

medic2891

Joined May 7, 2018
8
i am launching model rockets

what i have so far is power coming in to red switch on right side then to volt meter to check battery power then to key switch then to led green
from there i want to go to red arm sw also test i don't no how to configure the rest
 

ericgibbs

Joined Jan 29, 2010
13,833
hi,
For the 12V batteries, I would not connect them in parallel.
If you need 24V, then two 12v batteries would give 24v.
Do the rocket igniter's require 12V or 24v.?
Are there any relays in the project.?
E
 

ericgibbs

Joined Jan 29, 2010
13,833
hi,
Without more detailed description of the project or a circuit diagram, it is not possible to help you to proceed.
E
 

Thread Starter

medic2891

Joined May 7, 2018
8
here is my work so far i need 2 things one to wire the controller the other one is the charge box what want is to wire the charge wires to the charge box and to the battery back to the charge box

thank u
 

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Reloadron

Joined Jan 15, 2015
6,123
A Learning Guide for Model Rocket Launch Systems is a very good read from those nice people at Estes. The guide includes several schematics of basic launch systems. Most model rocket launchers (the igniters) require 12 Volts so a good solution is placing two 12 Volt batteries in parallel. Actually depending on your battery capacity (Amp Hour Rating) one good SLA (Sealed Lead Acid) battery should suffice. Typically a 7 AH battery or greater is used. Electrical Current Requirements of Model Rocket Igniters is another very good read on the subject. While only a short duration the igniters draw quite a bit of current. You need to take that current draw into consideration This is where you want to consider the wire run from launcher to actual rocket launch pad. The link suggest AWG 16 wire stranded but depending on wire run length you may want to think about AWG 14 stranded copper wire.

As to maintaining the battery you may want to look at an off the shelf 12 Volt battery maintainer. Frequently called a Battery Tender and come in several flavors from distributors like Amazon. I use one of these for my motorcycle during winter storage. I see them from $10 USD and up.

Ron
 

-live wire-

Joined Dec 22, 2017
922
Maybe consider a high voltage arc lighter. It will consume a lot less power and will give you many more uses. Just make sure the current is limited to non-lethal levels, and you are well educated in electrical safety.
 

Reloadron

Joined Jan 15, 2015
6,123
here is the wire diagram so far question how do I add a test sw and led
Page 7 of the link I provided shows a circuit using a test lamp which can easily be a LED with a series resistor. The idea being the igniter will not see enough current to ignite the engine but the illuminated lamp will show continuity through the igniter. When the launch switch is closed the test lamp will extinguish and the igniter will ignite the engine.

A typical Red LED will have a forward voltage of about 1.2 Volts and a forward current of about 20 mA. So with a 12 volt launch system you have 12 - 1.2 = 10.8 / .020 = 540 Ohm series resistor for the LED. As a common off the shelf resistor 560 Ohm would work in this case. The linked diagram clearly shows how the test lamp is configured. I suggest you read it and then apply it to your drawing.

Ron
 

Thread Starter

medic2891

Joined May 7, 2018
8
Page 7 of the link I provided shows a circuit using a test lamp which can easily be a LED with a series resistor. The idea being the igniter will not see enough current to ignite the engine but the illuminated lamp will show continuity through the igniter. When the launch switch is closed the test lamp will extinguish and the igniter will ignite the engine.

A typical Red LED will have a forward voltage of about 1.2 Volts and a forward current of about 20 mA. So with a 12 volt launch system you have 12 - 1.2 = 10.8 / .020 = 540 Ohm series resistor for the LED. As a common off the shelf resistor 560 Ohm would work in this case. The linked diagram clearly shows how the test lamp is configured. I suggest you read it and then apply it to your drawing.

Ron
where is the link thanks
eddie
 

-live wire-

Joined Dec 22, 2017
922
here is the wire diagram so far question how do I add a test sw and led
Please try and make the schematic as neat as you can. If you don't know the circuit symbols, that's okay, but try to show the components connected in a coherent way. Remember, except for the added resistance, the shape of the wires does not affect the circuit. Just the actual connections. It is much easier to understand and troubleshoot a circuit that is neater without wires going in every direction.

Here is a circuit that does what you were asking about. The resistances of the wires and switches are not intentional, but rather an annoyance that will always be there. Use thinker wires to minimize it. Screenshot (11).png Live Wire
 
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-live wire-

Joined Dec 22, 2017
922
You can add some super caps in parallel with constant current from battery to handle much higher currents momentarily than your battery can supply. You can add two leds with resistors that have a fV if close to the maximum voltage so you know when they are charged.
 

Ylli

Joined Nov 13, 2015
1,053
Here is a circuit that does what you were asking about.
NAR Safety code requires a removable safety 'key' that, when removed, disables the launcher. It can be a key switch where the key is removable in the 'off' position, or as simple as a headphone jack that uses a shorted headphone plug to enable it.
 

Thread Starter

medic2891

Joined May 7, 2018
8
NAR Safety code requires a removable safety 'key' that, when removed, disables the launcher. It can be a key switch where the key is removable in the 'off' position, or as simple as a headphone jack that uses a shorted headphone plug to enable it.
there is a key that is removable when in off pos only
 
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