Category Archives: Meters

Here you will find information about our home made meters for measuring frequency, capacity, induction and other parameters.

Bipolar Power Transistor Tester h21E

Bipolar Power Transistor Tester h21E

Here you will find our development for a bipolar power transistor tester. It measures the short-circuit forward current ratio (Iout/Iin @Vout=0) commonly known as h21E.

Gallery

 

Schematics

Bipolar Power Transistor Tester h21E
Bipolar Power Transistor Tester h21E
( as PDF)

 

Bipolar Power Transistor Tester h21E PCB
Bipolar Power Transistor Tester h21E PCB
( as PDF)

Descriprion

Commonly in everyday practice we need to use two or more bipolar power transistors in parallel, in a push-pull schematic. In order for the transistors to work with identical parameters of currents and gain, as well as to minimize the non-linear distortions, and to reduce heat peaks, they must be with the same h21E parameter.

The unit works like a current generator and measures the base current of bipolar power transistors N or P type. By reading the milliammeter you can quickly compare the h21E values of the measured transistors and to select those with similar parameters for work in a couple or in parallel.

The parameters in the schematic are for a milliammeter with 100 microamperes and internal resistance of 1000 ohms. If you need to use a meter with different values from the above, you need to recalculate R 3,4,5,6,7,8 depending on the new internal resistance. The device and the schematic are easy to implement.

Good Luck!

More Info

Frequency and LC Meters

Frequency and LC Meters

Here we have put the diagrams of our devices for measuring frequency, inductance and capacitance. Options Frequency meter v3.1 (2003 – 2007) 1Hz – 1000MHz Frequency meter with functions v2.4 (2004 – 2005) F1: 1Hz – 1000MHz F2: 1Hz – 50MHz F3: 1Hz – 50MHz Frequency and LC meter v1.2 (2005 – 2008) 1Hz –… Continue Reading