Electronics Forum / Basics / June 2008

    --Have been googling around to find the little inverter/sequencers
for blinking various strings of electroluminescent wire for an artsy-fartsy
project. What I can't find are robust ones capable of running more than
short lengths of the stuff. What I'm looking for is a 12-v driver ...

If i consider an opamp in corrent-to-voltage configuration with:
-ideal generetor current in inverting input
-non inverting input to ground
-feedback resistance equal to 100Mohm

What is the benefit with comparators that have a Hysteresis pin?  
I'm using one the LTC1440 and I don't see any benefit you still
require two resistors for Hysteresis. Is the Hysteresis pin tied
internally to the output (positive feedback)?

I have a circuit requiring a 25MHz clock signal, all the components I
can find are 4 pin 25Mhz crystals - how do these differ from the 2 pin
crystals in my spec?
Dave

I was looking at a 12 volt regulated power supply at Dick Smith
Electronics cat. number M9935 @ www.dse.com.au for a regen radio I'm
planning on building (http://www.schmarder.com/radios/tube/
1-12af6.htm) but the AU$24 is a bit too high for my liking. I was

Has anyone on this forum taken a course from the "Cleveland Institute of
Electronics" (CIE), and if so, what is your opinion of the school? Is it
worth the money?
If you don't won't to reply on this newsgroup, please email me at jcd (at)

I bought  a bunch of vacuum tubes from a surplus electronics store
that was going out of business, so many of them weren't marked as to
what tubes they were-- but they were cheap. One in particular is a
large eight inch tube that has four pins at the bottom and two

I have a set of battery, but I only one hooked up to the circuit, The
other one act as a backup. I want to implement an electronic unit that
will change (swap) the batteries.Therefore the wiring will need to be
changed. The circuit need to support 5amp of continuous current. Here

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My boss asked me to evaluate oscilloscopes and to recommend one.  I know
Tektronix and LeCroy.  Which is better?  Are they any others?  Ideally, we
would get a 4-channel scope at 300 MHz, with a 5 million sample record
length.  Thanks for your advise.

I have an outdoor dawn/dusk timer for use outside. My main use has been for
Christmas lights, but now I need something like it for a pond. I'd like to
set it for say 8 am to 6 pm, or slight variations to turn on the fountain.
Anyone know where I can get a more flexible outdoor ...

I have the following questions, can anyone explain to me how the
following circuit works, how does the first op-amp oscillate, and how
does the buzzer sound?
The first op-amp is configured with negative feedback, which normally

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I've only done a little soldering before, but I want to rebuild a
battery pack for my TI-59 calculator (which is basically 3 AA-sized
batteries soldered together in series).
Can I just solder directly onto the battery terminals? With a copper

Is the joint contact on http://www.geocities.com/anglomont/hvr-d.jpg
connected to anode of 2x062h(it should be a diode) ?