Electronics Forum / Basics / July 2006

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I bought a potentiometer at Radio Shack, but it doesn't fit on my
breadboard.
How do most people attach these to breadboards?
Thanks.

I just dropped my 20 year old Radio Shack digital multimeter and it
stopped working.  I use it probably once a month so I want to order
another DMM.  
Does anyone have a recommendation for a good basic DMM in the $50 +/-

I have built this basic sound to light 555 schmitt trigger circuit
The circuit I am using (see fig.9) is at this link:
http://www.uoguelph.ca/~antoon/gadgets/555/555.html
The R1 & R2 are 220k, c2 is omitted,and its powered from a 12v car

See the original text.
16          Franck-Hertz experiment is not quantized
Ed 01.12.31 ----------------------------------------
Abstract

I am looking to power a USB "dongle" from a 12 volt battery.  From what
I've read USB is 5V @~100mA.  I'd like to build a voltage regulator to
do this, and I'd rather not lose half of my power to heat.  Can anyone
point me at a circuit that is more efficient then a standard voltage

If I put a potentiometer on this circuit, will it serve as a decent
volume attenuator?
http://electronics.howstuffworks.com/telephone5.htm

Is this a good idea? How low a temperature can they take?
I have a few spare used cell phone Li-ion batteries that I may want to
use for other applications, and I was reading some web info indicationg
they should be stored at 40% charge inside a refrigerator. I'm

Hi, got a question about those starting caps on AC motors in pumps,
washing machines etc..
Why are they so freaking big while having so low capacity??
If I was to replace one of those, can I substitute it with a usual

Couldnt continue last night as google seems to put a posting limit on
folks now.... I would continue this morning but I must go to work.
Tonight I will try and find some other web based usenet access
sites...preferably something non US without posting limits......

can someone help me to make code for digital clock using AT89S52. The
specs of clock are 12 hour clock,am-pm display,use timer interrupts to
have delay.two external inputs to adjust hours and minutes,use 4 digit
hex display multiplexing.

Hi, im trying to get my head round ground loops and after some
verification of my limited understanding.
Looking at the driver of RS485, you measure the voltage between the
output_A and output_B. These go straight into another op-amp in the

I have seen a IMO cool gadget lately in a hotel. Instead of a mechanical
wall switch, you basically found a metal plate of about 2 inch diameter.
By touching this plate shortly with your bare finger, you switched
on/off the room light. By touch and hold your finger on the plate, ...

It has been a while since I fooled around with electronics when it was
part of my education. So now, I am wiring up a few projects. Here's my
question:
Can I use a car battery to power a 555 timer circuit and a load that is

Hi, can anyone explain the purpose of the drain wire when there is
already a foil shield on the outside of the wire? Is it to allow a
better shield connection as the foil is quite resistive?
Thanks,