Duoyi DY294 component and isolation tester

Video review

The front

This is a small battery powered transistor tester but it can do more. It can test Vbr, hFE, Vce sat and  Iceo. It can test transistors, fets, diodes, leds, zeners, SCR, isolation of MOVs, capacitors, etc

hFE, also called Beta is the DC amplification parameter. It is the ratio between the base current and collector current. There is also hfe, or alfa, the small signal amplification parameter. This is the ratio between the change in base current and the change in collector current.  Beta is not a constant. It is not lineair. This tester has 3 different base currents, 10 uA, 1mA and 10mA. Be careful, you can fry a transistor in a flash. As soon as you set the switch on a hFE position it starts measuring. I had rather seen that the pushbutton worked for all functions and not only for HV. Voltage is max 6V, Ic is 2A foor the 1mA and 10mA range and 58uA for the 10uA range.

Measured: Ic: 2A, 2A, 58uA, at 5,98V
                  Ib: 9,979mA, 0,996mA, 9,92 uA at 5,98V

Vbr, the breakdown voltage  is for isolation testing. It generates 1500 or 270Vdc and shows the voltage the component breaks down. You can use this also to test f.i. zeners. The current is low, 544uA for the 1000V range and 712uA for the 200V range.

Measured, Ice: 544 uA at 1622V and 712 uA at 234,8V

Vce(sat) is the saturation voltage, this is the voltdrop over collector and emitter. This must be very low for switching semiconductors so the dissipation is low. Open voltage is 6V. Ic is 2A, 800mA, 100mA or 10mA

Measured, Ice: 1,94A, 0,829A, 100mA, 9,436mA
                  Ib:  150mA, 76mA, 9,9mA, 0,979mA 

Ice, this is a leakage current measurement. It has 1 uA resolution. The voltage is 26V, max current is 2000uA

Measured: 1660uA and 26,25V
DMM            DY294
1657uA            1670
2,66uA             0002
1660uA            1665
1188,4uA         1191
518,36uA           511
259,97uA          260

The capacitor connectors are to test the Vbr or Ico of capacitors (not for electrolytics) However, the Ice is usable for low voltage electrolytics. 

4 batteries or an external 6Vdc

It uses 4 AA batteries or an external 6Vdc powersupply. For the Vce 2A and 800mA you need the external psu.  

Soldering was not great to put it mildly. 

The main pcb. Right top is the HV part

Under the display is a blobbed IC

Piggyback board with the current resistors.

Backside of piggyback board

The zero position of the knob

Location of the contacts. Be careful, they lay more or less loose on the disk.


This entry was posted in Bridges and component testers, Measurement gear. Bookmark the permalink.

Comments are closed.