Hey everyone! I'm on the lookout for two compact devices that beep when they're separated and stop once they're back together. They need to communicate via radio frequency (RF), not Bluetooth or internet. Ideally, I'm aiming for a range of 100 meters to 1 kilometer. One device will be attached to my wallet or pouch, and the other can go on a keychain or inside a phone case, so one should be small enough to fit between a phone and its case. I'm hoping to find something commercially available, but if I have to go DIY, it needs to be low power for a long battery life. Any recommendations for products or ideas? Thanks!
3 Answers
You should definitely check LoRa devices! They can achieve long ranges and are quite power-efficient but fitting them into such a compact size might be challenging. If you're willing to stretch that size a bit, there are some creative setups with small antennas that might work. If you're looking for something pre-made, electronics markets or specialist stores might have products closer to your needs. Just remember, the size and power trade-off can be significant!
You might want to explore industrial proximity alarms; they often employ standalone RF systems. They can be a bit bulky, but there are models that operate on direct RF without additional dependencies. If none of that helps, going DIY with timer circuits and RF modules like ESP-NOW could totally be the way to go!
Finding devices that fit your specs is tricky! Most handheld walkie-talkies fall short in terms of real range, despite what they claim. Given what you've described, you could look into low-power RF solutions like a 433MHz module or the NRF24L01 for proximity alerts. These are compact and might work for your needs if tuned properly. Just be wary of regulations that limit transmission power, and possibly consider adjusting the transmission power and using an optimal antenna to stay compliant while maximizing your range!