Description
The Elektor Zener Diode Tester is essentially a constant-current source that can be switched in steps from 1 to 50 mA. It can be used to test Z-diodes up to a maximum of 54 V. Thanks to a 60-V step-up converter, the device can be powered by the usual 5 to 12 V.
The principle of this tester is straightforward. A Z-diode or other DUT (device under test, such as an LED) is biased by an adjustable current source. The voltage across the DUT can be measured with a multimeter. The voltage of most (small) Z-diodes is specified at a current of 5 mA. Depending on the application, the voltage at other currents can also be of interest. That is why six current settings are available: 1, 2, 5, 10, 20, and 50 mA. LEDs are often specified at a current of 20 mA.
What can be tested is:
- Whether a Z-diode is defective (short circuit or high impedance).
- Whether a Z-diode exhibits the correct Z-voltage.
- How a Z-voltage changes with different currents.
- What exact voltage is present at an integrated voltage reference.
- Whether LEDs in a series chain differ in brightness (hence the 20 mA current).
- What the current gain is for different base currents in (power) transistors.
The kit contains all parts listed in the bill of materials including PCB and enclosure.
Specifications
| Supply voltage |
5…12 V/2 A (USB-C) |
| Supply current (Itest = 50 mA) |
1.1 A @ 5 V / 412 mA @ 12 V |
| Selectable currents |
1, 2, 5, 10, 20, and 50 mA |
| Max. test voltage |
>54 V @ Itest ≥1 mA |
| Max. output voltage |
60 V @ Itest = 0 mA |
| Voltage limit at 5 V |
4.5 V @ Itest = 1 mA / 5.18 V @ Itest = 50 mA |
| Enclosure dimensions |
110 x 82 x 44 mm |
| PCB size |
105.4 x 67.3 mm |
| Connections |
4 mm banana sockets for multimeter |
| 2 mm banana sockets for test clips |
| USB-C socket for power supply |
Included
Resistors
- R1 = 3.3 kΩ, 600 mW, 1%
- R2 = 0.15 Ω, 1 W, 5%, LS 12.7 mm, ø 3.5 mm
- R3, R8 = 180 Ω, 600 mW, 1%
- R4, R6, R16 = 1 kΩ, 600 mW, 1%
- R5, R19 = 47 kΩ, 600 mW, 1%
- R7 = 3.9 kΩ, 1 W, 5%, LS 12.7 mm, ø 3.5 mm
- R9, R10, R12 = 10 kΩ, 600 mW, 1%
- R11, R13 = 100 Ω, 600 mW 1%
- R14 = 249 Ω, 600 mW, 1%
- R15 = 499 Ω, 600 mW, 1%
- R17 = 2.49 kΩ, 250 mW, 1%
- R18 = 4.99 kΩ, 250 mW, 1%
Capacitors
- C1 = 470 uF / 35 V, 20%, Ir = 1.86 A, ø 12.5 mm, LS 5 mm, ESR = 0.038 Ω (Panasonic EEUTP1V471)
- C2 = 1 uF / 100 V, 10%, X7R, LS 5 mm
- C3 = 2.2 nF / 50 V, 10%, X7R, LS 5 mm
- C4, C7 = 100 nF / 100 V, 10%, X7R, LS 5 mm
- C5 = 100 uF / 100 V, 20%, ø 14 mm max., LS 5 mm
- C6 = 1 nF / 100 V, 10%, X7R, LS 5 mm
Inductor
- L1 = 100 uH, Irms = 2.4 A, Isat = 3.5 A, 0.09 Ω, radial, pitch 2.5/5/10 mm, ø 14 mm max. (Kemet SBC8-101-242)
Semiconductors
- D1 = MUR120G, DO-41
- D2, D4 = STPS3150RL, DO-201AD
- D3 = Z-diode, 18 V, 1.3 W (BZX85C18)
- D5 = Z-diode, 5.1 V, 0.5 W (1N5231B)
- LED1 = LED in pushbutton S1
- LED2 = LED, green, 3 mm
- IC1 = MC34063, DIP-8
- IC2 = LM4040BIZ-5.0/NOPB, TO-92 (TO-226AA-3)
- IC3 = TL051CP, DIP-8
- T1 = BC327.25, TO-92
- T2 = STP40NF10L, TO-220
- T3 = IRF9510PBF, TO-220
- T4 = 2N7000, TO-92
Others
- K1, K2, S1, S3 = 2-way screw terminal block, LS 3.5 mm, max. 1.5 mm²
- connected to K1 = USB-C socket, 30 V/3 A, chassis mounted, wired, 9 x 16 mm
- connected to K2 = Banana Connector, 2 mm, Socket, 60 VDC, Panel Mount, red (Multicomp 24.102.1)
- connected to K2 = Banana Connector, 2 mm, Socket, 60 VDC, Panel Mount, black (Multicomp 24.102.2)
- Test clip, red, 30 VAC/60 VDC (Hirschmann 931467101)
- Test clip, black, 30 VAC/60 VDC (Hirschmann 931467100)
- S1 = Pushbutton, panel mount, SPST-NO, 30 DC/100 mA, with red LED
- S2 = Rotary Switch, 6 position, 2 pole, 30°, 250 V/150 mA
- S3 = Toggle switch, panel mount, SPDT, solder lugs, 28 VDC
- T2, T3 = Heat sink, 15°C/W, FK 214 SA-CB
- Enclosure Hammond 1591XXSSBK, ABS, 110 x 82 x 44 mm
- Knob for S2, round shaft 6 mm, ø 21 mm, with indicator line (Multicomp CP-LB21-6-6D)
- 4 x Self-tapping screw #4-1/4", carbon steel, pan head
- Banana plug, red, 2 mm, 60 VDC (Multicomp 25.205.1)
- Banana plug, black, 2 mm, 60 VDC (Multicomp 25.205.2)
- Banana socket, black 4 mm, panel mount
- Banana socket, red 4 mm, panel mount
- for LED1, LED2 = Pin header, 1 x 2, vertical, pitch 2.54 mm
- for LED1, LED2 = Pin socket, 1 x 2, vertical, pitch 2.54 mm
- for T2, T3 = M3 screw, 10 mm, steel, pan head
- 2 x M3 washer, plain, steel
- 4 x M3 nut
- for IC1, IC3 = DIP-8 socket
- Wire, black, 0.25 mm² (24 AWG), stranded 14 x 0.15 mm, 1 m
- Wire, red, 0.25 mm² (24 AWG), stranded 14 x 0.15 mm, 1 m
- PCB 250772-1 v1.1
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