Electronics Forum / Electronics / October 2004

I used to use an HP frequency counter in the 70's, which measured
about 3' by 3' by 3'. It weighed slightly less than a house, it had an
incredibly powerful and loud fan, and a removable module. I'm guessing
it was made in the 60's. The digital display was made of Nixies.

Does any one know of a manufacturer/supplier of optically isolates
audiocables that I could use to connect a small biofeedback device that
generates a tone to the microphone input of a PC?
Thanks in advance for you help

I don't want to bore holes in my house to put a cable TV outlet into
another room. Does anyone know of a low power transmitter/receiver
combination which will run on house power, which will function as a
"wireless cable" and for which I don't need some sort of license? I have

Hi there all,
I want to use a LED on  24v DC what formula do i use to calculate what
resistor i need...?
the LED is a 10mm..... 30mA..... 2 volts

Questions.
1. I've found online a NiMH D-Cell boasting 11,000 mAh for $9.  Can that be
true?
2. The few Li-ion in D-Cell config I've found have pathetic milli amp hours.

I would like to lower the speed of my 12"  fans. They come with a 3-step
speed control but even the lowest speed is too fast for me.
Is there a simple way of doing this? Resistors?
Thanks

Hi, my mother recently had a co-worker give her some Raytheon CK722
transistors in their original packaging.   They were found in the
attic of his new home.  They have the blue tops and each is in the
envelope packaging.  I'm not sure what year they're from, but the

Could someone please explain or help direct me to an explaination of what the
difference between, say, a 2-head and a 4-head VCR, a Hi-Fi and Lo-Fi VCR, so
forth ... also, are any VCR's out there able to record quadraphonic or dolby
5.1/7.1, even though a good majority of TV shows ...

Ok. Here's how it'll work. You'll need to get a number of 9-volt batteries. To
enter, connect as many 9-volt batteries together in series as you please, touch
the ends, and send a photograph to KellyClarksonTV@cs.com . Person with the
most batteries in series after 100 entries wins ...

Guys,
Anyone know where i can get a grunty servo at a reasonable price ?? I
want to use it to automate the turning of swimming pool valves i.e.
the large plastic handled valves you see on the 40 and 50mm hi

Please i need help finding  3 - 100 farad  capacitors 16 - 20 volts
please email me at ruserious_phx@hotmail(dot)com
please replace (dot) with  .
thanks

Has anybody done anything (projects) with it or is it just a learning toy?
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I need schematic and knowledge on this issue.
the design
the output signal has to  feed into serial port o window 98 / 95 based IBM
note book.

I'm looking for a circuit for switching off a Central heating pump after a
delay up to (max) 2 mins adjustable (after boiler has ceased firing) using
SCR , Triac or similar, 240 V @ 2Amps approx max.
regards

I own a Cingular v60 and when I hook it up to my hf carkit, the backlight
gives off an irritating feedback (kinda maybe) hum, sorta like a 60 cycle
hum.  Only happens when the backlight is on.  Not really noticable when
using a conventional headset.  Is there a filter I can install ...