Zener Diode tester

[BANNEDMemberAccount]

The circuit can be assembled on a Vero board.
    Use a 9V PP3 battery for powering the circuit.
    The capacitor C3 must be rated at least 150V.
    Use a holder for mounting IC1.
    T1 can be a 110V primary , 9V secondary step down transformer connected in reverse.

Meron nakong 555 timer IC, pero wala pakong trafo na 110v to 9v.

meron pa bang mas simple nito ?
o kahit complicated nito basta mas maganda

[rdpzycho]

rekta sa 220V 'yung trafo, 'yung secondary depende kung gaanong kalaki 'yung Zener na susukatin. so kung ang maximum nung Zener is less than 20V, ok na 'yung 24V na trafo. pwede rin sa DC supply na lang ikabit.

malamang kasi 'yung design niyan is for portability at hindi na kailangan ng AC supply.

[Macgyver]

bakit may R3 and R4 pa na magkaiba value?  Nagiiba ba ang voltage sa zener depende sa current?

[BANNEDMemberAccount]

Mga sir may nahanap pako, medyo simple lang, ang taas lang ng volt na kailangan


PARTS LIST
R1    4.7 KΩ
R2    2.2 KΩ
R3    2.2 KΩ
R4    1 KΩ
VR1    47 KΩ LIN
D1    RED LED
IC1    LM741

<<<Dito sa site na ito>>>

ito ang description niya:

Zener Diode Tester Circuit

This tester helps to check the voltages of zener diodes. It is very inexpensive and  handy to find the voltages of small glass zeners, whose markings get rubbed-off very easily. The 741 op-amp has been used in differential mode.

The 47k linear potentiometer’s dial is calibrated in terms of voltages between 0 and 27V, either by using various known zeners in the range, or by applying a known voltage at pin 3 of IC 741. The position of the potentiometer where the LED gets turned off, gives the breakdown voltage of zener.

The power supply voltage can be between 9V and 30V. But zener to be tested, and should not be changed once the dial is calibrated.

You can also check the polarity of zener. The cathode side should be connected to the red clip.(i.e. pin 3 of IC 741) If you connect the zener the other way round, then it will just behave as a diode, and the LED will remain off at all positions of the potentiometer.

In case of a zener that is shorted from inside, the LED will remain off with zener connected either way ti the clips. In case of a zener that is open-circuit from inside, the LED keeps glowing at all positions, with zener connected either way to the clips.

You may even differentiate between a diode and a zener by their behaviour on this versatile tester.

[rdpzycho]

bakit may R3 and R4 pa na magkaiba value?  Nagiiba ba ang voltage sa zener depende sa current?

110V kasi 'yung secondary sis kaya pwedeng itaas 'yung resistor value, baka kasi masira 'yung zener.

@sis Red, mas madali 'yung una, tester lang, mahirap 'yung pangalawa dahil may pipihitin ka pa at para lang sa isang voltage kung ifi-fix mo na 'yung trimmer.

[BANNEDMemberAccount]

^ oo nga po may vr1 pa, ang dami ko kasing zener diode na binili nde kona alam yung mga volt niya ibat iba pa, problema konalang yung trafo nito

[Macgyver]

di ba pwedeng

variable bench power supply >  high value resistor >  zener > gnd.  Tapos voltmeter na lang na nakaparallel sa zener? 
Tapos  pihit ng bench power from 0v to 12v (depende kung ano max value ng zener) tapos kung saan na "stuck" yung voltage ng voltmeter eh yun na yung value ng zener?

meron din akong mga zener na di ko alam ang value.

tapos yung zener ko mga glass type.  para tuloy signal diode.  pano kaya matest kung zener ito or normal diode?

[rdpzycho]

^ pwede 'yang bench supply sis. actually, mas maganda kung constant current source, around 10mA, 'yan kasi 'yung kailangang zenering current.

reverse connection kung merong voltage. kung wala kasing voltage, normal diode siya na mataas ang breakdown.

[torpedo]

nice..