GDamiani2927
commented
3 months ago Possible options:
- 5V Relay: Easy to use, hard to use well. The 5V relay utilizes an internal electromagnet to toggle a switch on and off. This physical means of toggling works for most application, but with such a small margin of error, this isn't great. Time for switching varies by product, the ones we have access to to (Songle SRD Relay) actually have a very short release time (max 10msec), and switch current at a maximum of 7A at 240 VDC, which easily encompasses our range. However, the minimum operating voltage of the relay is 5V, and the Pico can only supply around 3.3V. Using this relay would involve additional batteries and voltage control, and would likely be less convenient in the long run than the alternative.
- MOSFET Power Transistor: Hard(er) to use, eas(ier) to use well. The MOSFET Transistor is a powerful way to switch high currents in a very short amount of time. The setup of the transistor itself is simple, however every transistor is very different, and if careful attention is not payed to the datasheet of the specific model, problems can arise. When staying within the parameters of the model however, a MOSFET is likely the best solution to this problem. The IRLB8721 Power MOSFET, the easiest for us to access, has a high current capacity, making it ideal for our application. That said, a transistor circuit will significantly slow down our progress, and will likely require testing of its own at various voltages and currents.
The Electromagnet that we are using to connect our payload to the launcher runs 15V @5A, meaning that we need to utilize a DC power supply to sufficiently power it. Eventually, we hope to find a way to power the magnet without the use of a power supply, but until then, we have to devise a way to switch the electromagnet on and off quickly and consistently. This poses a difficult issue, as any power switching device we use has to be able to withstand a 5A current, which isn't possible for most components we have in the lab.