Test Gear Circuits


Posted on Feb 7, 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 555 timer 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


Test Gear Circuits
Click here to download the full size of the above Circuit.

the unloaded ac voltage is around 120volts ac. This is rectified 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. This circuit is the result of Andy Collinson research. He has used a photodiode, SFH2030 as an infra red sensor. A MOSFET opamp, CA3140 is used in the differential mode to amplify the pulses of current from the photodiode. LED1 is an ordinary coloured led which will light when IR radiation is being received. The output of the opamp, pin 6 may be connected to a multimeter set to read DC volts. Infra red remote control strengths can be compared by the meter reading, the higher the reading, the stronger the infra red light. He aimed different remote control at the sensor from about 1 meter away when comparing results. For every microamp of current through the photodiode, about 1 volt is produced at the output. A 741 or LF351 will not work in this circuit. Although he has used a 12 volt power supply, a 9 volt battery will also work here. 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 555 timer is used in the astable mode, the output at pin3...




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

CodeLock AVR
Ultrasonic range finder circuit
btr200
im3500
LED Volt Meter Circuit LM324
Baxendall tone control circuit
Xbee doorbell project
NOAA WEATHER ALERT DECODER
TDS9092 TDS971 IEEE-488/RS232C
Pulsed Magnetic Field Therapy (PMFT) Circuit



Top