Zener Diode Testers

Posted on Feb 5, 2014

Using a single 555 Timer IC and a small transformer to generate a high voltage, this circuit will test zener diodes of voltage ratings up to 50VDC. The 555timer is used in the astable mode, the output at pin3 drives a small audio transformer such as the LT700. This has a primary impedance of 1K and a secondary impedance of 8 ohms. Used in reverse the unloaded ac voltage is around 120volts ac. This is rectified

Zener Diode Testers
Click here to download the full size of the above Circuit.

by the 1N4004 diode and smoothed by the 2. 2u capacitor which MUST be rated at 150 VDC. The zener under test is measured with a multimeter set to DC volts as shown. The load current switch enables the zener to be tested at 1 or 2mA DC. The rectified DC load, but a good zener should maintain the reading on the volt meter.

Leave Comment

characters left:

New Circuits



Popular Circuits

Two-wire Lamp Flasher
PC mains switch
15V And 5V Car Battery Supply
Telemonitor For Recording Phone Calls
low noise receive aerial
Class A MOSFET Amplifier 2SK1058
simple 2 watt small switching power
12 volt power supply circuit diagram using LT3845
Complete SS Laser Power Supply Schematics
T3SE type 3 SE
XTR108 reverse voltage and overvoltage protection circuit diagrams