For fans of the launch of small rockets the availability of an electronic system with key that prevents accidental firing, a very important resource. The electronic launch system we describe is simple to assemble, but efficient in ensuring that the shot occurs only at the right time.
When the S1 is switched on, the ignition system consisting of a nichrome wire (wick) on the rocket can not be heated unless a safety plug with the trip switch is inserted into the J1 jack.
In this way, even if some "cute" closes S1, or that its accidental activation happens, without the presence of P1 in J1 it is not possible to make the shot.
In figure 1 we have the complete diagram of this interesting security system.
In figure 2 we have the arrangement of the components that must be closed in a box of wood or plastic for the correct use.
The batteries must be large, given the current requirement of the fine nichrome wire, which is normally used in the ignition of this type of rocket. The relay, of 6 V can be used equivalent.
The jack is of the type for earphone or else a common socket in case P1 is a corresponding plug.
For the connection of the long wire to the wick we recommend the use of antenna / earth terminal pair or screw bar.
On assembly, observe the polarity of the LED relative to the batteries.
How to use:
Keep the plug with the trigger switch in your pocket and make all the preparations for the shot.
At the time of launch, turn off S1 (The LED goes out) and insert the plug into J1.
Turning on S1, the LED lights up and indicates that the system is ready for launch: Countdown and at zero press S2 which is a pressure switch.
The wick can be obtained by breaking a 10 W wire resistor of any value between 100 ohms and 500 ohms. The bit of nichrome wire will be connected to a common connecting wire that comes from the trigger.
PARTS LIST
B1 - 4 large batteries
S1 - Single switch
S2 - Pressure switch NA (normally open)
K1 - Any sensitive 6 V relay
LED1 - Common red LED
R1 - 1 k ohms x 1/8 W - resistor - brown, black, red
J1 - Phone jack
P1 - Phone plug
Miscellaneous: Mounting box, battery holder, antenna / ground terminal, wires, solder, wire resistor to make the wick (see text), etc.
