A small neon bulb, like the common NE-2 indicator lamp, typically has a breakdown voltage of around 90 volts. This is the voltage required to initiate the glow discharge within the bulb.
This breakdown voltage, often referred to as the striking voltage or ionization voltage, is the potential difference needed to ionize the neon gas inside the bulb, allowing current to flow and producing the characteristic orange glow. Once the neon gas is ionized, the voltage required to maintain the glow (the maintaining voltage) is lower than the breakdown voltage.
Here's a more detailed breakdown:
- Breakdown Voltage: ~90V. This is the voltage needed to start the glow.
- Maintaining Voltage: Typically lower than the breakdown voltage, often around 60-70V. This is the voltage needed to keep the glow going once it has started.
The exact breakdown voltage can vary slightly depending on factors such as the specific gas mixture, electrode shape, and ambient temperature. However, 90V is a good general value for small, indicator-sized neon bulbs.
Therefore, for practical purposes, when designing circuits involving small neon bulbs, it is safe to assume a breakdown voltage of approximately 90 volts.
