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33 Threads found on edaboard.com: Transistor Triggering
hello, I have built a one transistor forward converter (10W) for 240V 50Hz mains. It is an isolated version of an otherwise identical one which was non-isolated and worked fine. However, this isolated one is not working well at all. I am getting only some 2 Volts across the 11 Ohm load. It is strange because the MOSFET gate drive pi
I HAVE PROBLEM WITH TRIGEERING CIRCUIT FOR 555 IT is made using diode and transistor
I have a circuit that is essentially a shock alarm. It uses a piezo shock sensor. The main circuit is based around an LM555 chip such that the shock sensor triggers the LM555 which drives a transistor which drives a horn. The 555 chip is being used in the standard monostable configuration. The circuit works properly except that when it is first pow
Hey guys, I need to trigger a transistor circuit, which in turn will activate a recording circuit to record audio from a "double male ended headphone jack". I need the head phone jack to trigger the circuit when there is sound on it. It will be used with a two-way radio to make a simplex repeater. A radio will be waiting for a message, and when
You need more current. As the opamp doesn't supply sufficient current, you need an emitter follower (NPN bipolar junction transistor), such as 2N2222 or equivalent transistor. Make sure you add a series resistor to limit the current to about 200mA. use a base resistor of about 200 Ohms to avoid current peaks from the opamp. If your suppl
"Code for the gate pulses" suggests a microcontroller interface. Most simple method would be an opto triac, it can work for thyristors as well. Unfortunately you'll lose part of the dV/dt strength that thyristors have in contrast to triacs. A pulse transformer is the more rugged method, it can be driven through a transistor output stage. UJTs are a
rambus_ddr is correct about the resistor. The resistor is used to develop a small gate voltage (~ Vt, threshold voltage) to help provide more uniform triggering of the transistors. If your transistor model accurately models the parasitic capacitance then you can size the resistor to produce between 1 and 2 Vt's on the gate in response to a (...)
You can solve temperature problem by increasing initial current to transistor collector. I think 1mA current will be OK. Place appropriate resistor from Vcc2 to transistor collector.
the principle goes like this.. a fixed reference base voltage (lower than Vbe) is applied in an off-state NPN transistor (biased by the resistor). when temp rises, transistor Vbe goes down, thereby, triggering the transistor when it reached a Vbe lower than the reference voltage.. when the transistor (...)
Hi whitewiz Seems like you don't quite understand the ESD triggering using this approach. In order to be safer, I suggest you to replace the final transistor to an NMOS transistor with gate connected to Vb, which is then a typical RC gate coupled structure for you to be more familiar with the basics first. Otherwise, you may fail finally (...)
I am designing buck regulator too. Main source of switching noise is power switching transistor. For struggle against switching noise I use - placing power NMOS and PMOS in different wells; - placing cells of regulator in different wells; - guard rings around cells; - different supply and ground buses for power and control parts; - decreasin
I built the SRFo4 unit as shown in the schematic from Devantech. I used a PIC12F508 rather than a 'C' device as my stockist only carries the 'F' version. I changed the processor statement in the source code to reflect the 'F' device. I am triggering the module from a 555-based oscillator - transistor inverted to give a 10uS high level, with a
do you agree that the diac always conducts whenever the top transistor is onClearly no, see the diode polarity. It keeps C2 discharged and prevents further triggering of the DIAC after startup.
A charge pump can be used for disabling ESD protection during normal operation. For instance you could use an ESD protection transistor that is turned on unless its gate is biased highly positive (beyond Vdd) or negative. Thanks for the discussion. ESD is always trouble for me too When would this be used? Th
I was hoping someone might be able to help me figure out an issue I'm having with a 12v trigger. I have a NuVo Grand Concerto system and an older amp, without any 12v trigger, powering one of the zones. Thus I tried to add a Russound ACT-1 (voltage triggered AC outlet) to power on/off the amp with the 12v zone trigger from the NuVo. Problem is the
Hi, Is there a transistor or any other element that when the is a signal on the gate It shuts off the connection between base and emiter ? Not quite sure what you mean (gate is for FETs, base+emitter for bipolar) but are you talking about a transistor with a sort of "negative logic"? Maybe a PNP then. If the collector
You can use a transistor to boost up the triggering for your relay to function. Please check out the section on transistor, Hope it helps.
I have a remote controlled one celling fan speed controlled + one light on/off circuit. The circuit is consist with one 8 pin IC, one optocuplor, one relay, one BT 134 and one 547 transistor, and few resistance and capacito. It is very simple circuit without using microcontroller, so I want to make this circuit which will be cheap for me and my fri
The transmitter flashes the LED very rapidly. This is to increase it's brightness by driving it at high(ish) current but for short periods so it doesn't overheat. The receiver picks up the flashes in the photodiode as a tiny voltage change and amplifies it so the signal is bigger in the 741 op-amp. The amplified signal is then converted to DC in
In my view, Wikipedia gives a good, not too complicated explanation of basic thyristor operation: Particularly the two transistor equivalent circuit is helpful to understand how it works, provided you already understood the transistor. Otherwise, it's most likely too hard and you should go back to the
When selecting a transistor switch for the lamp, you have to consider the rated current and the inrush current of a cold filament. BC547 most likely isn't able to supply it.
greeting people, Can i replace an general purpose optocoupler(pic817) with optotriac(moc3020)? from what i tested, i notice the optotriac output remains ON althought i have disconnected it input, in other words optotriac output latched. does anyone knows how to unlatch or switch off optotriac output? please help. thanks.[/QUOT
How about using a NOT gate and edge trigger the 555. Feed the inverted input signal from the NOT gates output, through a 0.001uF ceramic capacitor with a following pullup resistor. Or if you don't want to use a NOT gate, just a transistor would do the same
If you understood that circuit enough to get it to work, then allthough maybe not a leccy, you are definately an electronics enthusiast. The system described above is in common use in motor starters, and most relays tend to be double pole so should be easy to do, in fact you can do it with a single pole if the transistor is a high enough rating.
You can add optotriac instead of transistor which it enhance safety of your board.
just a transistor is more than enough. see the circuitry..
One key question is, is there a reasonable upper limit to the overvoltage-to-be-withstood. If yes then an "off" condition of a transistor may be preferable (if its "on" is suitably low resistance). But semiconductor devices often fail shorted and may not be suitable for all safety apps. Now since it is overvoltage, you don't need a passive s
How did you deduce that it is this pin that is causing the problem, and not some other part of the circuit? If, however, it IS this pin causing the problem, maybe somehow false triggering the photo-transistor, you can pull down this pin with a 10k resistor to ground. Hope this helps. Tahmid.
2 amp for the LEDs will be really scary for me.....you really need the power LED for my view you need to choose right LED first...... Normal LED can work max up to 100mili-amp so be careful... and second important point is what is the level of voltage i mean voltage level ....I think you can have low voltage like 3 volts but in that cas
I would make two comments: 1. The 100K resistor in the base of the transistor is *probably* too high in value. It depends on the relay specification which you have not supplied but a value of 10K or less would be more normal. 2. I would add a diode (1N4148 or 1N400x) across the relay coil, cathode end to +VCC. it should not normally conduct but a
Come to think of it, the output might not be strong enough to drive a relay. In any event, you can feed the output to one of the following switching devices: transistor mosfet scr triac solid-state relay Etc.
As shown, the circuit will have hardly ever worked. AT89C51 series has only ?A high output current. You'll either change the circuit to active low drive or use a transistor (or both). I would always prefer active low, otherwise the processor will activate the valve in reset state.
For a first guess, have a look at 555 timer application notes. If you want zero current consumption in off-state, a different approach might be required, e.g. using CMOS logic ICs or transistors.