Electronics Forum / Basics / May 2007

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I am trying to change a noninverting op amp of an existing circuit so
that it is inverting. Since I am just starting out with op amps I am
confused as to why simply switching the inputs does not work- I am not
getting any output in that case.

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Ive been working on some projects for university and my lectuerer has
suggested that i replace a LCD screen with an OLED one. The scrren
does not have to be full color but it could be an option. I simply
need a screen which can be used to display high visibility text. LED

I need to make a relay switch on 1 second after a 12VDC line comes on, but switch off immediately the 12VDC goes off.  What's the best way to do this?  If you need to know why I want this, see the paragraph below:
I have a solar power setup and wish to switch the load between the ...

Hi, not sure if anyone can help me but I am just starting out in
electronics.  I have bought a multimeter so I can go through a book I
bought 'Starting Electronics' by Keith Brindley.  I am trying to
measure amps on it but cannot see where I can do it.  I didn't buy the

I had an hold cheap iron and I tore it apart. Essentially it uses a wire
wrapped around a ceramic cylinder with another ceramic cylinder on top.
I took about two inches of the wire which is about awg 30 or 29 and it
measured about 30 ohms.

It seems that there is a relationship between
frequency and the voltage drop across an
inductor or resistor. If you have a series
circuit consisting of an inductor and resistor,

Not sure if this is the right place to ask, but give it a go anyway.
I need a small switching device to trigger and stop an ambulance siren.
Can anyone help?  I am totally ignorant in this matter and would be
willing to pay for the finished product.  We are in London, UK.

Hello to the group,
I am looking for a way to get pc boards that will allow me to mount a
40 pin micro, and still have some holes on either side of the pins to
mount things like pulldown resistors, caps,etc.

I calculated the frequency response of the CS and Cascode amplifiers
using the time constants method. Here they are:
CS
f = ( 2*PI*( Rs*Cgs + Rs*Cgs*(1+Av) + Rd*(Cdb+Cl)) )-1

I tore apart the battery transformer I mentioned here a while back. I'm
going to remove a few turns on the primary to increase the voltage across
the secondary(its 24.2VAC now and I'd like to get that to about 30VAC or
so).

Good day.
I recently removed some crystals from some old electronic devices but do not
know what frequency they are.
Is there an easy and accurate way to determine their freqs?

Hi all.  This is my first post to this NG forum, so please be kind.
I am trying to repair a 12v latching relay for my Volkswagen Beetle
(~1975).  It controls the dimming of the headlights (hi/lo).
The trigger is a momentary ground signal (S) which actuates the coil.

I have finally decided to break down and buy a oscilloscope. But I
found I don't know what to get. As this will be by first oscilloscope I
don't need any thing fancy. I don't have a lot of money so a used one
would be fine, if it had a manual or I could get one. I would be