Low Powder Alarm for Hornady Powder Measure

thingiverse

This is a low-powder alarm for Hornday powder measures. It consists of a very simple buzzer circuit tripped by a float. The float rides on top of the powder. When the level reaches a pre-determined limit, the arm on the rod closed the switch, activating the buzzer. The limit can be changed by sliding the arm up or down on the rod (the arm is a very tight fit to the rod). The buzzer consists of batteries wired to an active piezo buzzer with a micro-switch in series. A 3.5mm headphone jack is used to connect the switch (on the lid) with the buzzer box so that the lid can be easily disconnected and removed. The housing of the buzzer box is made of two parts glued together (housing + adapter). There are holes for 3mm screws that can be used to align the parts and hold them together while the glue dries. The buzzer box is secured to the funnel with 14" zip ties. Electronics parts: * buzzer: https://www.adafruit.com/product/1536 * switch: https://www.adafruit.com/product/820 * 2xAAA battery holder: https://www.adafruit.com/product/4192 * headphone jack: https://www.adafruit.com/product/3692 The headphone cord and plug was "donated" by an old set of headphones. Anything with a 3.5mm male plug will work. The rod is 12" long 1/4" square brass tube. Aluminum would work just as well.