Level indicator for liquid in drink container - contains electrodes and PNP circuit detecting change in resistance when electrodes contact liquid

摘要

The arrangement contains two electrodes mounted at a fixed distance from each other and a transistor circuit connected to the electrodes which responds to the change in the resistance between them when they come in contact with a liquid. Both electrodes are fixed, electrically insulated conductors with free ends which act as a mounting for the drink container and define the fill level. The transistor circuit contains two pnp transistors which take no current when the electrodes are insulated from each other but which generate an acoustic signal when the electrodes contact the liquid. ADVANTAGE - Simple, economical arrangement can be easily used by blind people or people with limited vision.