Hobby Electronics Basics

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Serial Port Design for Z80 - Questions

Greetings! I wanted to add a serial port to my 1981 Gorf arcade machine. Since it is really just a specialized Z80 comp...
14 comments posted 17yrs
posted by cmdr-dave
14 comments posted 17yrs posted by cmdr-dave

Semiconductor markings

I have a transistor marked D401-Y, made by SEC. I see data sheets marked CSD401, 2SDS401, KSD401, MPD401. I think it's...
1 comments posted 17yrs
posted by notggod.email
1 comments posted 17yrs posted by notggod.email

741 gain

Thank you all. It's set up as simple inverter, with (+) pin to ground via same R as the input R and only 100Hz. Still w...
0 comments posted 17yrs
posted by pccmd
0 comments posted 17yrs posted by pccmd

Derate switch for DC?

I'm looking for switches to control standard automotive 12v relays. Coil current is about 200 milliamps. I need mom/off...
2 comments posted 17yrs
posted by amdx
2 comments posted 17yrs posted by amdx

wall wart and leds

I am trying hookup a 10mm superbright led to a wall wart that is rated output 9v, 300ma. I used a 470 ohm resistor for...
5 comments posted 17yrs
posted by medusa569
5 comments posted 17yrs posted by medusa569

ua741

I'm aware of uA741 slew rate issues and limited GBW, but I can't even get above gain of 2x with Vcc of +/- 12v and input...
13 comments posted 17yrs
posted by pccmd
13 comments posted 17yrs posted by pccmd

error in translation

it ain't spool in english (a translation error on my behalf) but coil. What's the formula to calculate the force between...
1 comments posted 17yrs
posted by vro_hans
1 comments posted 17yrs posted by vro_hans

Vector Network Analyzer Question

I don't know how the display processor block of a VNA usually work. I have scoured through a few application notes, but...
0 comments posted 17yrs
posted by stanigator
0 comments posted 17yrs posted by stanigator

simple output filter question

Here's a question that has been bothering me for a while. I want to make a simple lowpass output filter. With time cons...
31 comments posted 17yrs
posted by ggherold
31 comments posted 17yrs posted by ggherold

How do I initialize a D flip-flop?

Hi, I'm working with a 74AC74 D flip-flop. I wanted it to power up in a predictable state namely with the Q output low....
4 comments posted 17yrs
posted by zeb7k
4 comments posted 17yrs posted by zeb7k

spools

What's the formula to calculate the forces 2 spools have on eachother?
1 comments posted 17yrs
posted by vro_hans
1 comments posted 17yrs posted by vro_hans

What is the symbol for a mic?

I want to write (by hand) if some voice recordings of mine are in mono or stereo. Are there some standard symbols used...
52 comments posted 17yrs
posted by dummy
52 comments posted 17yrs posted by dummy

Blinded By The Light!

Recently I had a peculiar experience with a car driving up the street. This car had on its top a very thin pipe that fl...
3 comments posted 17yrs
posted by ryon
3 comments posted 17yrs posted by ryon

Seasonal Circuits

Just a couple of ideas for maybe simple winter circuits. A battery charger that would charge lead acid batteries automa...
3 comments posted 17yrs
posted by regor
3 comments posted 17yrs posted by regor

Trying to hold stepper motor and measuring

The stepper is turning and I try to hold it (with my fingers, or something stronger). How can I sense and measure the r...
14 comments posted 17yrs
posted by aleksazr
14 comments posted 17yrs posted by aleksazr