Tagged Questions
-3
votes
0answers
33 views
RTL state confusion [closed]
My textbook says that if Vin1 is 0V and Vin2 is 5V, then both transistors are off, but I think that the upper transistor must be in saturation mode. Why is it off?
2
votes
2answers
198 views
leds in parallel, switched with NPN transistors
I have the following circuit designed to drive 3 PWM pins off a 3v3 Arduino Pro Mini -- one pin for each of R, G, B in this set of 5 RGB LEDs.
simulate this circuit – Schematic created ...
2
votes
2answers
95 views
Constructing a simple emergency light kit
This is my first adventure in the electronics world and, as I'm a CS student, you can expect a lot of associations that maybe aren't that right.
The main feature of my circuit is:
If there isn't ...
1
vote
1answer
224 views
Alternative to optocoupler? Other switching devices?
I have a part that classifies what kind of power I get on ethernet by presenting different loads. For example, the part needs to have a 100 Ohm resistor across two of its pins, and the part will ...
0
votes
1answer
65 views
NTE2013 base inputs
I have an NTE2013 which I want to use with an Arduino. I may be driving the base pins directly off of the Arduino or perhaps off of a 74HC595. Should I use resistors between the outputs and the base ...
0
votes
1answer
334 views
how to choose the transistor for following case?
I planned to use the following circuit to run unipolar motor. I got this circuit by surfing internet. I know how to choose the transistor for driver circuit by knowing the base current, but in this ...
3
votes
2answers
894 views
1.8V to 5V, still not comfortable with transistors
I have a H-bridge IC L293DNE that needs 5V input signals to operate, however my available outputs are only 1.8V from a Gumstix Overo GPIO pin. I have a power supply that supplies me with +5V 1A.
I've ...
5
votes
2answers
733 views
Transistors: why are resistors needed?
I have a solid state relay which needs at least 3V to activate, and I need to toggle with a 2.3V output from a microcontroller. I've also got a 6V 1A power supply which I can use to power the relay.
...
0
votes
1answer
147 views
How to properly store components efficiently and effectively [duplicate]
Possible Duplicate:
What's the best way to store and categorise resistors/capacitors/ICs/etc?
I have MANY resistors and many other components as well and currently I am using a very ...
26
votes
5answers
2k views
Why do you need 2 resistors when hooking up a transistor as a switch
What is the point of R2 in the following diagram:
I get that R1 controls the current to the Base, but what does R2 do?
Thanks!
3
votes
3answers
938 views
Determine suitable resistor for the base of transistor as switch (NPN)
I have designed a program to count the frequency and time period of the pulse generated by a 555 timer IC using PC Parallel port. I’ve connected a base of BC547 (NPN) transistor to the output pin (no. ...
1
vote
2answers
334 views
Not use current limiting resistor for switching device on off using TIP122 possible?
I wanting to control MP3 player and amplifier box through PIC board.
My project is doing announcement when person standing in near PIC board with proximity sensor.
When proximity sensor detecting ...
1
vote
1answer
372 views
What kind of resistors do I need to use in this Canon remote switch, if it is possible at all with the P2N2222A transistor I have?
I'm a total electronics n00b set out to create an intervalometer for my Canon EOS 350D camera which seemed super simple from the outset, but I got a bit blocked with creating a switch using a ...
8
votes
6answers
2k views
Inexpensive solid-state variable resistor
I have an analog audio project I'm playing around with designs for and it will need about 150 solid-state variable resistors. I plan to control these from a micro controller so a digitally controlled ...
