Aysu Sarı <[email protected]> writes: > The current that is sent by the Telemetrum needs to melt the fish > line instead of firewire. Can Telemetrum do that or can i make it do > that?
Hello. The design of the pyro circuits on Altus Metrum flight computers including TeleMetrum provides is a FET switch to ground on one terminal and pyro voltage on the other. So in a normal configuration, you attach an e-match, and when the channel fires the FET switch closes the circuit and causes the match to fire. Whether TeleMetrum can help you melt your line depends on two things: The first is how much power you need... we can switch a ridiculously large amount of current, but TeleMetrum provides the unregulated voltage from the LiPo which is in the range of 3.7-4.2 volts. It's possible to use some other voltage source, ignoring the v_pyro terminal and just using the FET switch to ground to close the circuit on some other battery. We should be safe with any battery up through nominal 12V, on the order of 15V absolute max. The second is how long the power needs to be applied. All of our flight computers including TeleMetrum default to a 50 milli-second on time, which is way more than enough to fire a typical e-match. Bench tests I did some years ago showed that 13-15 micro-seconds was enough to fire the commercial e-matches most of us use. However, this may be too short to melt a bridge wire wrapped around fishing line. Unfortunately, for TeleMetrum, the only way to change this is to customize the firmware. That's entirely possible since everything is open source, but may or may not be within your capabilities. Our TeleMega and EasyMega boards with 6 pyro channels allow the "extra" pyro channels to have a user defined pyro on-time, so one possibility would be to switch to one of those boards. It's also entirely possible that you could build up a small circuit with it's own battery, FET switch, and a timer / pulse generator configured to trigger on our FET closure switching a pin to ground, such that your switch "latched on" for as long as necessary to melt your line. I hope this helps. We've seen teams work around rules against loose black powder in the past, but this is the first time I've heard of a contest that doesn't allow pyro charges at all. Please let us know what you end up deciding to try, and how it works out! Regards, Bdale
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