Minecraft wiki entry for Dispenser, associated text: When activated, a dispenser waits for 2 redstone ticks (4 game ticks, or 0.2 seconds barring lag) and then ejects one item. The dispenser does not continue to eject items while activated; ejection occurs only on the initial activation (the rising edge of an input signal). To eject multiple items, repeatedly activate the dispenser with a clock circuit. If the clock runs at faster than 5 Hz (more than 5 redstone pulses a second), the dispenser fires once and then locks in the "on" position.