Kingtronics Blog

The Ceramic gas discharge tube can be used in all places that have over-voltages.We should decide the parameter of the GDTs base on the need of the actual circuit and then select the suitable GDTs,
otherwise,we may get the reverse result.The following is the notice when using  the Ceramic gas discharge tubes:

1)Must avoid affecting the normal operation of circuit when using the Ceramic gas discharge tube.
2)Confirm the maximum peak voltage that the circuit can bear,make sure that the GDT's impulse spark-over voltage must be lower than it
3)Based on the possible impulse current energy to select the necessary impulse discharge current volume of  the Ceramic gas discharge tube
4)When the over-voltage disappears, the GDTs must extinguish rapidly to avoid affecting the normal operation of the circuit.
5)If over-voltage lasts significantly longer, GDT's discharge may continue for an extended period and generate significant thermal energy
6)Select suitable volume of  the Ceramic gas discharge tube according to the applied space.

Since the voltage dropped across a Zener Diode is a known and fixed value, Zener diodes are typically used to regulate the voltage in electric circuits. Using a resistor to ensure that the current passing through the Zener diode is at least 5mA (0.005 Amps), the circuit designer knows that the voltage drop across the diode is exactly equal to the Zener voltage of the diode.

NEW Click here to visit Zener-Diode.co.uk for a site dedicated to zener diodes, their characteristics, usage, and other information.

Zener Diode Voltage Regulator Circuit

A zener diode can be used to make a simple voltage regulation circuit as pictured above. The output voltage is fixed at the zener voltage of the zener diode used and so can be used to power devices requiring a fixed voltage. Click here to find out more about the Zener Diode Voltage Regulator and how you go about selecting the resistor and zener diode.
NEW The above mentioned article on zener diode voltage regulators has now been updated and a handy calculator has been added to help you select the correct resistor and zener diode values and power ratings.

Zener Diodes in Series With Loads

If you have a regulated fixed voltage - say 12 Volts from a desktop PC power supply, and you want to power something requiring a lower voltage, it is possible to simply place a zener diode in series with the load device. You would choose a diode with a zener voltage equal to the supply voltage minus the voltage drop across the load.

For example, if you have a 1 Watt 6 Volt lightbulb to power from a 12 Watt regulated power supply, a 6.2V zener diode could be placed in series with the bulb giving the bulb 5.8V, or you could overpower the bulb a little using a 5.6V zener diode and dropping 6.4V across the bulb. Heat would be generated in the zener diode so it is essential to calculate the power lost in it so a suitably rated diode could be chosen.

Using a 5.6V zener diode, and knowing the bulb draws a current of around one-sixth of an Amp, we can calculate the power loss in the diode (with Ohm's Law) to be just under 1 Watt. Therefore a standard 1.3 Watt zener diode should be up to the job.

Circuits with Zener Diodes

Zener diodes are key components in the circuits presented in the following articles: Make a Simple Battery Status Monitor, LM741 Voltage Indicator, and High Capacity Alternative to 9V Battery.