[Q] use Keyestudio Electromagnet Module

[eadmaster]

will this module work as alternative to the proposed circuit?

https://www.keyestudio.com/products/keyestudio-electromagnet-module-for-arduino-diy-projects

[zacharyweiss]

Good question! In short: I'm not sure, but it's worth a shot.

The longer answer is:

• The product states it draws 0.3A (and, somewhat contradictory, 3W, implying 0.6A), which nominally should be safe to pull from the Flipper (which has a fuse set for 1.2A on the 5V pin). That said, it's possible there would be transient draws larger than this, or that flipping back and forth could cause the fuse to blow somehow anyway. Hence, do so with caution, and possibly start by just testing feasibility powering it externally and only using the F0 to enable/disable the electromagnet.
• To match the standard speed of swiping a card, the app plays data back with a 200-700us clock. If the inductance of this electromagnet is too high, it's possible it won't be able to switch back and forth fast enough. I'm not an electrical engineer, but if my memory of undergrad circuits classes serve me, the time constant here should be L/R (inductance over resistance), neglecting any wonky effects from the ferrite core (retentivity/hysteresis/etc). My uninformed guesstimates would put resistance at ~10ohms, inductance at ~1-100mH, putting the time constant on the order of milliseconds, not microseconds. Hard to say without an actual datasheet (and someone with more EE knowledge than me) or just testing it, but that might make it too slow.

Either way, curious to see what comes of you trying it! Keen for updates if you decide to give it a shot.

[eadmaster]

thank you for the tips, i'll make some tests with a CC1101 module first.