9
votes
Accepted
Will this 3.3 V signal voltage be high enough to close Q3?
(Your current question title says 3.3 V while the text says 3 V, so I'll use the lower of the two.)
Driving PWR_ENABLE with 3 V will be plenty to switch the whole ...
- 23.6k
7
votes
Is my setup for a 5V motor project faulty?
You have the transistor "upside down." It should be like this:
simulate this circuit – Schematic created using CircuitLab
The arrow in the transistor symbol points towards ground. ...
- 72.5k
4
votes
Will this 3.3 V signal voltage be high enough to close Q3?
Q3 is a darlington pair, meaning that you require \$V_{BE}\approx 2\times0.7V = 1.4V\$ to switch it on. A potential of +3.3V at PWR_ENABLE will be adequate in this application, because collector ...
- 38.9k
3
votes
Accepted
Why does this transistor amplifier fail if Rc is greater than 50 ohms?
I wonder about accurate simulation of RF, using your current understanding of bipolar circuits. But I'll drop that and move on.
A couple of bad things done in that ...
- 11.2k
3
votes
Import transistor into LTSpice
Similar question has been answered here.
You encountered an error because of a missing dot before the SUBCKT. I have corrected it in the script below. Save it in a ...
- 1,226
2
votes
Transistor switching speed
I won't go further than a very simplified (1st order) model of what's going on to help develop a meaning for \$f_t\$. There are higher order models. But to a first order the following approximation ...
- 11.2k
2
votes
Accepted
Help with circuit analysis - Transistor, dc-motor, arduino, resistors
Let me draw your circuit with some annotations that I can refer to later:
simulate this circuit – Schematic created using CircuitLab
Your equation for \$R_B\$ was calculated as follows:
$$ R_B =...
- 38.9k
2
votes
Finding relationship between saturation current and Vgs for MOSFET?
There's never a guarantee that a certain amount of current will flow, given some particular \$V_{GS}\$, because it varies so much even between devices from the same batch. Even if a datasheet does ...
- 38.9k
1
vote
Switching ON/OFF an ADC line
Well, there's a couple possibilities:
Don't care. If the input currents are small enough, there's no wear on the ESD clamp diodes*, and VCC lifts imperceptibly against the normal loads on it (MCU ...
- 39.6k
1
vote
4N25 Optocoupler design
You have a wee bit of an issue with a 100Ω load and this circuit. Generally you'd like the base current of the transistor Q2 to be 1/10 to 1/20 of the collector current, which argues for an R6 of ...
- 407k
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