How do you match transistors in pairs?
A pair of transistors will be “matched” if the voltage at the base/emitter and current amplification are identical. The extent of precision may be from “vaguely same” to “exact” and can be tweaked as needed.
What does it mean when two transistors are matched?
Matched means the transistors were selected from a pile by measuring them to find the two that “match” closest for a particular variable, presumably the one you care about.
How do you select an equivalent transistor?
Step by step instructions:
- Choose a transistor of the same polarity: The first major selection criterion is whether the transistor is PNP or NPN.
- Select a replacement transistor of the same material: Most transistors are either silicon or germanium.
How do you use a multimeter to match a transistor?
Because the transistor base terminals are connected together, the measurement is the difference in VBE of Q1 and Q2. If the multimeter reads 0 V, we know the transistors are matched!
What does well matched transistors mean?
Matched pairs are transistors that were fabricated on the same piece of silicon at the exact same conditions. This reduces the danger of one the transistors reacting to heat at a different rate than the other causing ever greater current to flow through it and thus heating up even more.
Does it matter what transistor i use?
For most general purpose transistor applications we need devices which are non-conducting with zero bias on the control input (base or gate). Such devices are BJTs or enhancement mode MOSFETs. But do we need a BJT or a MOSFET? In many cases it does not matter.
What are the factors to consider in substituting the transistor?
Depending on the application and type of the original transistor, the basic areas of concern are the voltage, power, current, switching speed and amplification characteristics of the substitute. Other areas that may also be important include the lead locations on the transistors and the mounting options.
What are identical transistors?
The most basic application of “identical” transistors is a current mirror: Where TR1 converts I1 into a (VBE) voltage which is then applied to an identical transistor TR2 which then makes a copy of I1 flow, which is I2.