It is the ability of the special FET's that is so attractive. I think without being rude we all knew that. The idea of T03 out of T0220 came from the fakes. It would be sold under the understanding it needs it's stability to be checked. A ready made feedback pair in the style of a Darlington could be interesting. This would be in DIL 8 and have access to the resistors. Also a longtail pair with 2 x 100 R already fitted. BCV 61 and 62 as DIL 4 device, better still 2N5401 or 2N5551 as ready made current mirrors. One thing if I were a rich man I would like to do is build more ideal devices using existing device silicon. Exicon 10N/P20 and BUZ 900/905 ( and 2SK/SJ devices ) are source to case and only need a variable resistor as bias. The other FET's I mention IRF530/9530 need source resistors and a Vbe bias adjuster to thermally trachk the heatsink temperature, some designs take a risk on that. The problem with source resitors is they would need to be large in value to force good behaviour. If looking at the thermal simplicity and the ability to go direct to heat sink thius is no small thing. I dare say if so power output is less than optimum. Even if you don't use matched sets they tend to self compensate. As they test them after prduction they put them in groups. Smile and don't fret over capacitance straw men - enjoy Exicons, Alfets, On-semi and Toshiba's biggest as we have for decades, whilst you still can.Īs said before the source resistor can be left out if pre matched devices are bought. I suspect we will be without TO264 case parts in the not too distant future. For BJTs, we still need larger packages for the lower temperature safety margins but with commercial demand falling, who's making new parts and support products like thermal pads for low demand BJTs and LMosfets? I have a hard time getting even cut sheet silpads and mica is as scarce as hens teeth for the large pads! What this means is that smaller package parts can be used because there is no second breakdown to be cautious of and if more power is needed, jam in more devices. Even up-market audio is largely Mosfet, and a steady creep to class D is in progress as it improves. Audio power is actually a small field compared to general power control, which is now the domain of Mosfets and little real development now goes into linear audio power. So if you are looking for a medium power NPN transistor in Plastic package then this Transistor might be the right choice for you.TO264 and TO3P packages are becoming orphaned as mainly for BJTs. Due to this feature this transistor is widely used in amplifier applications. This reduces the cost of the Transistor and also since the package is not conductive it will not be affected by other noise in the circuit. It also has a very less saturation voltage (Base Emitter Voltage VBE) of only 5V, this makes it easy to use this IC in digital electronics which has an operating voltage of 5V.Īnother peculiar fact about this transistor is that it comes in plastic package, while most medium power transistor are available only in metal can package. The BD139 was originally manufactured by Phillips rated at 160MHz for specific audio applications, later they were cloned by other manufacturers like Samsung, ST etc.īeing a Medium Power NPN Transistor with a collector current of 1.5A this transistor can be used to control (On/Off) bigger loads that consume less than 1.5A. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (VCE) or Base-Emitter (VBE) could be 80V. When this transistor is fully biased then it can allow a maximum of 1.5A to flow across the collector and emitter. To bias a transistor we have to supply current to base pin, this current (IB) should be limited to 1/10th of the collector current and voltage across the base emitter pin should be 5V maximum. The maximum amount of current that could flow through the Collector pin is 1.5A, hence we cannot connect loads that consume more than 1.5A using this transistor. TIP31C, SL100, S8050, BC547, 2N2222, 2N4401īD139 is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pinīD139 has a gain value of 40 to 160, this value determines the amplification capacity of the transistor. Note: Complete Technical Details can be found at the BD139 transistor datasheet provided at the bottom of this page. Emitter Base Breakdown Voltage (VBE) is 5V.Collector-Emitter voltage (VCE) is 80 V.Continuous Collector current (IC) is 1.5A.Current Drains out through emitter, normally connected to groundĬurrent flows in through collector, normally connected to loadĬontrols the biasing of transistor, Used to turn ON or OFF the transistor.
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