Electronics Forum / Basics / February 2007

Tony
Nottingham
England
22 February 2007

please send me all discussions & messeges

I came across this pcb design software that I just finished a project with
and found pleasant,
www.diptrace.com
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I've tried to use a Velleman timer kit for time-lapse photography with
my Pentax DSLR camera but the single relay output isn't enough.
The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact

Dealing with leds..I have few questions.I am trying to make matrix of
64 leds,common anode and darlington pair are used as current sinks for
individual leds. leds at 5v@25ma of current. I need to design a power
supply which will be enough to supply  64 leds i.e 25ma x 64 = 1.6A of

There's a schmatic symbol in Sam's PhotoFacts # 2908 and 2753-1
(covering JVC TV sets av-2749s, av-2759s, and av-2779s) that I don't
recall ever having seen before.  It's NOT listed in the parts section
so I have no original or replacement numbers for reference.

I'm kind of new to this electronics stuff. I took a class years ago
and have a pretty good idea of how basic circuits work. I don't have a
clue about IC's.
I am working on a little project which I don't know how to set up. I

I have a electronic device that uses an OEM ($$$) wall wart rated at
5VDC and 220mA. In my collection of transformers I found one rated at
5VDC with the same plug/ polarity except it's rated at 500mA. Would it
be okay to use or should mA ratings match more closely?? Thanks.

I have beautiful DC panel meters that currently reads 0-5Volts DC by
using an in-series resistor.  I want to use this meter to instead read
0-5 AC AMPS.  This is to help me judge excessive power consumption on
my train layout.

I have a 4 digit 7-segment display that I mux through a MPU (illuminate one
digit, wait a couple ms, go to the next digit... like this:
http://www.melabs.com/resources/articles/ledart.htm).  This switching is
causing terrible noise on the power bus that is really messing with my

Have a newbie question for you. I have  this burglar alarm that has
some very specific current draw requirements. It works on 12VDC. One
set of warning horns cannot exceed 120mA current draw from a
particular set of output terminals. I have a  collection of small

Could someone explain to me if there is a rule of thumb to determine
the peak pulsed power of an (linear class a/b) RF amplifier if the
peak cw power is known. For instance,
if the amp is rated 300W (max power) in cw mode, the max power in

I am a std of BE electronic engineering. Now a sophomore, I had a bad
result in the freshman year. An overall result of 64.6 percent and
failure condoned in two subjects namely basic electrical engineering
and chemistry.

Hi all, I am replacing the old bulb type side marker lamps on my
trailer with the new LED ones. I purchased a tridon 2 pin solid state
flasher to replace the old one. My problem is that now the new LED
lights stay on and do not flash. Help!

first of all, sorry if my English is far from perfect: it's not my native
tongue. Anyway, here we go:
I built myself a reflow oven from a modified / power-increased toaster
oven and a self built controller. I'd like to make small runs of boards.