Tagged Questions

0
votes
3answers
90 views

Logic Circuits Vs Transistor Power Circuits

I have need to invert a signal to drive fets with hard/fast rise and fall times. I was told in another thread to use an inverter (NOT chip). This makes perfect sense to me since logic chips are ...
3
votes
2answers
123 views

How to read the datasheet of a Digital transistor?

Could anybody please help in understanding the parameters of Digital transistor from its datasheet. Basically i need two parameters which decide the Maximum voltage for off state(0 state) and minimum ...
1
vote
2answers
107 views

Automating Filling of Humidifier - Logical OR Gate

I have an Ultrasonic Humidifier that I use to humidify my shop. I have to fill its 2-gallon tank daily which is becoming a nuisance. Rather than connecting it to a larger tank, I have opted to ...
1
vote
1answer
71 views

Random-delay gen

Some years ago I tried to design a circuit where (among other things) a LED flashes after a kinda random delay. As it didn't work, (and after raging and destroying everything that could help me solve ...
7
votes
4answers
722 views

How are logic gates created electronically?

So we have AND, NOT, NAND, NOR, OR gates, but how are they created electronically/electrically? For example, what makes NOT gate reverse the value?
4
votes
1answer
258 views

Selecting proper vales of Rb, Re and and Rbe in a NPN transistor emitter follower configuration?

I need to gate a TTL Tx pin @115000bps as the chipset that drives the RxTx lines do not implement UART BREAK for arbitrary time periods. As a quick hack I have come up with the following ...
2
votes
3answers
309 views

Understanding Flip Flops/Registers in Low Level

So I'm reading "Elements of Computing Systems" trying to really understand how everything works underneath (Any other book/article suggestions that would help would be amazing) Since eventually I want ...
0
votes
2answers
85 views

For gates of same drivestrength, what does gate delay depend on and how?

I was wondering what the effect of input capacitance or fan-in is on gate delay. Also, does anyone know of a relation that links gate delay with different circuit parameters (input load (fan-in), ...
1
vote
1answer
192 views

Phototransistor as a pull-down in digital circuit

I have very little experience with phototransistors. I'm trying to create a circuit that will effectively function as collision detection. I'm using OPB608A which utilizes an NPN transistor. My goal ...
0
votes
1answer
126 views

Broken NOR gate

I recently constructed a NOR gate using the following schematic but when one of the transistors is set to HIGH an led I connected to the output of the gate glows brighter, but the other one works ...
6
votes
5answers
401 views

Why are sum-of-products implementations more popular than product-of-sums implementations?

In my book about circuit design (Fundamentals of Digital Logic with VHDL from Stephen Brown and Zvonko Vranesic), the writers always prefer a sum-of-product for representing and implementing simple ...
1
vote
1answer
113 views

If I made an h bridge out of silicon controlled switches, would I still need a driver?

My question is relatively simple. If I arraged four silicon controled swithces, like the one here, to form an h bridge, could I drive it directly from the logic level? Since only gate to gate voltage ...
3
votes
2answers
3k views

How to invert a digital signal

I need a way to invert a digital signal i.e. if the input is high, I want the output to be low and if the input is low I want the output to be high. I think this can be accomplished with a single ...
2
votes
2answers
911 views

read 12V logic pin from arduino using an NPN transistor

I have an inductance sensor on a CNC machine that goes 12V high when triggered (open collector when not) . I want to read that input on my arduino who uses 5V logic. I was thinking I could just use a ...
1
vote
3answers
509 views

SRAM memory cell - what kind of flip-flop

There is a classic 6T SRAM cell (image from wikipedia): It looks like (two inverters in opposite directions and interconnected in and out) and works like some flip-flop. But what kind of flipflop ...
2
votes
3answers
553 views

Going from Transistors to Gates to…IC's?

So I am trying to understand I guess what is probably a basic concept of computers. I was taking a look at this previous question: From Transistor to Gates And it's accompanying link: ...
8
votes
3answers
841 views

Need an XOR gate that works up to 2 to 3 GHz

I have encountered an unusual situation in which I require an XOR gate that will function reliably when presented with a square wave input with a frequency between 2 and 3 GHz. I know that desktop ...
1
vote
2answers
1k views

NOT gate with PNP transistor

I'm trying to make a NOT gate, but with a PNP transistor instead of NPN. What would a wire diagram look like for a NOT gate with a PNP transistor?