Tagged Questions
1
vote
2answers
74 views
Voltage Controlled Attenuator
I'm trying to create a DC voltage attenuator which linearly scales the loss relative to an applied control voltage "Vc". In other words, K = Vout/Vin is a linear function of Vc. Vin is guaranteed to ...
0
votes
1answer
113 views
What voltage is put across the Tx+, Tx-, Rx+, and Rx- lines over ethernet?
I'm trying to figure out how to wire up an LED, probably controlled by a FET, for an activity indicator for ethernet. I'm not trying to make one that supports official error codes or anything, but ...
0
votes
0answers
72 views
Compliance question
Q. You have +5 and +15 volt regulated supplies available in a circuit. Design a 5mA npn circuit source(sink) using the +5 volts on the base. What is the output compliance?
This is what I've done:
...
2
votes
2answers
59 views
Problem on output compliance?
What is exactly meant by output compliance of a current source? I've read that it's the range of voltage over which the current source behaves well. What exactly does behaving well mean?
I've got ...
2
votes
1answer
73 views
transistor loop to limit the current
I am trying to implement the DALI TX/RX circuit below.
The description says:
The other transistor (T2) is controlled by the current flowing through the
resistor (R1). If a DALI slave unit is ...
-2
votes
1answer
85 views
transfer AC voltage to load
Good day, how can we transfer the AC voltage from the output of the capacitor towards the load (8 ohms)?
Notice that if we simply put the load in the output capacitor, the voltage there will be ...
2
votes
2answers
96 views
Maximum effective range of RG-6/U in CCTV
How long RG-6u i can use in my cctv? what's is the effective range using RG-6u?
2
votes
2answers
1k views
Driving a large 7 segment display using a micro-controller
I need to drive a large seven segment display (segment length is a about 2 inches) using a micro-controller (PIC 16F877). I've driven normal seven segments directly from PICs without issues, but I ...
4
votes
4answers
396 views
Replacing a switch with a transistor
I am working on a project on the Raspberry Pi, it is a bit experimental as I am learning the electronics side as I go along... please edit out any problems with terminology.
My aim is to replace a ...
1
vote
2answers
506 views
Switch between battery and dynamo to power bicycle lights
Voltage produced by the bicycle dynamo varies depending on what speed your traveling at. I have two 12 volt bulbs mounted on the bike at the front and at the rear. I want to power these bulbs using a ...
2
votes
2answers
2k views
Best way to get +5V or +12V or 0V from arduino pin
I am working on an eeprom programmer as an Arduino shield. There are two pins on my eeprom that require a 12V signal as part of the programming process. One of them is an address pin that I am also ...
2
votes
2answers
369 views
Transistor switch: How to commutate 4-6V rail with 0-3.3V signal?
I want my gate (fet) or base (BJT) to turn on at 3.3 v, I then want to have 4 - 6 volts on my collector or drain, and the same voltage as the C or D to be present on the emitter or source,how should ...
6
votes
4answers
637 views
Transistor with two voltage levels, Vb ≠ Vcc
Why is my transistor only driving 5V instead of 6V? How can I fix it?
I have a 6V, 25mA circuit running some LEDs. I can control them by connecting and disconnecting the positive terminal of ...
8
votes
3answers
1k views
Need help operating a transistor
I have a relay operated by an NPN transistor that needs some voltage applied to the base. I'm working with an arduino and if I give it a digital port, all's well. The circuit looks like this one:
...
