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247 Threads found on Darlington
The output darlington transistors conduct more when they heat which causes them to conduct more then heat more then conduct more then then heat more .... It is called "thermal runaway". An audio amplifier or opamp use diodes like you did in one circuit or a transistor to replace the diodes to also conduct when they are heated by the darlingtons to
Hi all, I have ORCAD Capture 16.6. In the software i implemented a darlington circuit taken from the example of an electronics book. The picture of the circuit is attached. The problem is that when i run the simulation i get double values of all the currents and voltages in the circuit. Can anyone help me in this regard. 134868[
TIP127 = PNP darlington. A typical use for pullup resistor is to shut off a P device. Whatever is the voltage at its emitter (more positive) terminal, that is the same voltage you should apply to the base. It may be okay to apply a slightly higher voltage, but there is a limit to this. Operating characteristics could be altered.
These are darlington transistors with a voltage drop hardly below 1V. A suitable MOSFET is clearly the better solution. Unfortunately you didn't mention the switched load current, but there are many "logic level" MOSFETs that fully switch on with 2 or 2.5 V Vgs.
It's a boost converter. The two transistors are arranged to increase gain (similar to a darlington or sziklai pair). The capacitor charge and discharges, causing voltage variations at the left-hand transistor. It creates hysteretic action turning the right hand transistor On and Off. The joule thief is a cousin of this circuit. The joule thief h
You find similar circuits in LM317 data sheets. Using a darlington doesn't make much sense, at least for output currents up to 10 A. Better use a regular PNP power transistor for lower voltage drop.
A TIP120 is not a single transistor, it nis two transistors connected as a darlington. Your circuit has nothing to limit the LED current so the LEDs will blow up. The maximum allowed current in a TIP120 is only 5A so you should use a powerful Mosfet for 25A.
Hello!!! i have a circuit whose output is 4.7 v and 143 micro Ampere now i want to drive simple led.. i want to increase current upto 10 mA , what should i do??? can i use darlington pair or else Thanks !!!
if output is collector, Zout is very high only due to leakage // Rc of the current sink. (NPN) so Zout on CB and CE is the same but ends being just the load resistor only. Base Input Zin=hFE*(Rbe + Re) where the latter is chosen to be larger than Rbe. So it can be high with a darlington or low with Re= zero Ohm Emitter impedance, Ze is the
The power darlington transistors need heatsinks. If the output voltage swing is as high as 8V RMS then the output power is 8W into 8 ohms and each darlington heats with almost 2W. The 741 opamp was designed 48 years ago! It is noisy and its slew rate cuts its high level frequencies above only 9kHz. A modern low noise audio opamp works perfectly to
You forgot to tell us how much current you need for the LEDs. The Texas Instruments datasheet for the CD4017 shows that it can typically supply an output current of 15mA into a 2V red LED with a 9V or more supply if you limit the power dissipation of each output transistor to below 100mW. darlington drivers are inverting and have outputs that go to
I have some ic which called sn754410 datasheet: This ic have two h-bridges with darlington transistors. My question is why there is a need in darlington transistors to create these h-bridges? there is no option to use regular transistors? maybe the high-current is the reason? if yes why darling
There is a difference between darlington transistor and darlington pair? What is darlington transistor in fact?
Good grief! You did not notice that many IC amplifiers are boosted like that? Guess what? The BD908 is an ordinary single PNP transistor but the TIP142 is an NPN darlington dual transistor that is completely different. The shorted schematic is from Unisonic in Taiwan (China). The TDA2030 was invented by ST Micro in Italy and their original
Dear All, I came across this schematic for opto-coupled output: 128155 We have FPGA out 1.8V and resistor 100Ohm to regulate the current for diode from MOCD207-M. I'm not sure how the other side works. 1. How works this circuit? 2. What is the purpose of the diode CDSU4148-HF? 3. What will happen if we put a s
Thanx for the schematic but there are not the same supply i the A and B variant. I did some fault finding yesterday and found a broken power darlington transistor "3-351" and it should be a 2N6053, so now I need to find a supplyer of that or a replacement.
ac coupled darlington inverter amp?
I presume you are referring to the circuit linked in post #1 126146 I would suggest some modifications. If no FET is available, you should at least use a darlington (e.g. BC517 for the NPN configuration) to keep the base current error negligible. Secondly, the output transistor involves a voltage gain for Rsens < 5
125970 Can i use this configuration to drive 12 VDC SSR Relay or 12 VDC Coil Relay ? Please suggest do i need to keep 220R Resistor in between 2 Transistor ? If i use as darlington pair directly will it damage PC817 ? Please suggest.
What does he mean by saying common emitter? Is he mean all emitters of the 7 darlington pairs are all connected together and with the common ground (pin #8)? Exactly. How to use pin #9? For inductive loads, such as the coil of a relay, could act as a protective device that prov