Electronics Forum / Basics / September 2006

I usually see crystals with 2-pins. Can anybody tell me what are the other
legs for in 4-pin crystal oscillator packages? Thanks in advance.
-- Hoi

When we say there is   110V AC, is that peak to peak?

I am looking for textphone access numbers in Holland and Switzerland.
I've done an extensive google search but haven't come up with any.
Any assistance on this matter is appreciated.
Thanks,

A circuit calls for 0,0047 micro farad capacitors.  I been supplied
with 4,7 nano farad capacitors and the circuit doesn't work.  Have I
made the conversion correctly?

I have a portable radio that uses the headphone cord as the antenna. The
radio's reception is very sensitive to movement of the headphone cord. I
want to build a plug-in device so that a telescopic antenna will replace
the antenna function of the headphone cord. The headphone will ...

Not sure if this is the correct group to post this. If anyone can
suggest a more appropriate place, please do so.
I've just built a stereo balanced audio line driver using a pair of
Texas/Burr-Brown DRV134s. I've successfully built these with AD

Hypothetical situation: a PCM audio signal [24-bit and monoaural] is
transmitted through an analog 3 Mhz AM carrier, an AM receiver on the
other end [tuned to 3 Mhz] picks up the signal, and the reciever is
attached to a device that can recieve, process, and decode the PCM

I'd like to create a 12V battery monitor and interface it to a PICAXE-08M
running at 3.3V.
What would be the best way to do this? I was thinking about using a 3.3V reg
for the picaxe and then use a voltage divider so the changes in voltage can

I need to build a device to measure the speed of a pine wood derby car.
One idea was to use two photo censors connected to a programmable logic
controller with the output going to a simple display. Is there an easier
way to accomplish this?

I would like to know more about RF Transmitters/Receivers to provide
wireless communications from one low voltage device to another related low
voltage device (ideally 6-12V).  I've looking around on the internet but I'm
still a little stuck.

I'm building a small  Boost regulator using an inductor, transistor
switch, diode and filter cap, but I cannot get enough current into the
inductor before the transistor starts dropping a large portion of the
supply voltage. I don't think the problem is related to the transistor

I have a question that I'm desperately searching an answer for. I am
wondering if it is possible (I'm pretty sure it is) to hook up the
telephone through my stereo (or even the computer). I have a group
meeting to host at my place, and would like to have a friend who will

Bit of a dumb question...
I have this 4017 decade counter chip that I want to use, but instead of
hooking up a clock signal (like from a 555 timer IC) to the CLK pin, I want
to be able to control the 4017 using a push switch.

I'm working on a project in wich I need to have a system running 24hrs
a day , power supply will be solar panels feeding a battery. Can any
one share with me formulas on how to calculate de Amp/hr for the
battery and the power of the solar panel?

I am looking for wireless small red light I can activate remotely.
You see, I morning meditate in the living room and want to alert my
wife upstairs
to not disturb me until I am done.