What is it?
Can I buy one?
A lot of hard work and personal time was given up in the design and manufacture of this product. If we get enough interest in the timer then we may start to sell them in a batch production format. Presently we have no timers ready to sell. It you personally want one then feel free to email at [email protected] and we can reserve one for you so that once more timers have been all finished and ready for selling you are guaranteed one! We are not quite sure of the price, but it will not break the bank. Again, if you want more details then email us.
How does it work?
The Timer is based around the PICAXE 14M2 Microcontroller. This is basically a mini computer. We at JSB Rocketry have written the code for the PICAXE in BASIC that enables it to be used in this configuration as a Rocket Recovery Timer! This code is downloaded to the PICAXE and interpreted. The timing and positioning of the Servo can be changed via variable resistor which gives an analogue value hence the need for a fixed voltage input as this value will change as the input voltage decreases or changes. However, simple easy to understand steps on how to change the delay and servo positions are explained below and the push to make PCB mount switch can aid with the setting of different parameters.
Four LEDs are included on the board, each one telling the user which state the timer is in. There is a Power LED, then two LEDs to show the user if they are setting the timer delay or the servo positions and also an armed LED. All values are saved to the EEPROM memory of the PIC which is non-volatile meaning that the saved settings can be accessed as soon as the timer is powered up. The RRT2 also differs from the RRT1 via having an on-board piezo which acts as a auditory means of knowing when the timer is armed. A PCB mount slide switch is included to allow an easier means of turning on and off the timer. The PIC can be reprogrammed without unplugging it from the IC socket as a programming socket can be connected to the pins to the right of the board (more details below). The timer can be triggered by either a broken wire or a G-Switch, either one of these triggering will start the delay automatically meaning there is no need to set a preference- these are connected via a internal OR gate in the PIC to the trigger input.
How do I configure the settings?
To set the Time Delay:
To set the time delay the potentiometer is turned to anywhere in this range (see picture below). This image shows the top of the potentiometer for ease of viewing. The timer is then powered on. Once the timer is powered on the user turns the centre of the potentiometer to the number of seconds that they want the delay to be. In this case it is a delay of 4 seconds. Each notch on the potentiometer is a second as seen here. The program button is pressed and the time delay LED flashed the number of seconds including the 0- which can be confusing!
Link to Simulator: http://www.polyplex.org/rockets/simulation/
How do I power it?
The Timer can use up to 13 volts. We tend to use double cell, 7.4 volt Lipo batteries. The RRT2 differs from the RRT1 because the RRT2 has a Voltage regulator on-board which makes sure that a constant supply of 5 volts reaches the PIC even if you use a power supply greater than 5 volts so a 9 volt battery could also be used. The timer simply controls the timing and positioning of a Servo Motors movement. Because of the 5 volt regulator it isn't recommended that a single cell lipo is used as this would change the ADC values. A 2 cell should be used for optimum performance and it is small and light enough to mount on your rocket.
We at JSB Rocketry are happy to answer any of your questions regarding the timer. The Operation, the Manufacture and Availability of the RRT2 are all open to discussing. If you want to just leave any comments or constructive criticism in the form below please feel free.