Moving to SMT
I want to move to SMT components. Do I need a hot air reworking
station, or just a hot air station?
Can you recommend something for
someone with a small budget?
#10131 Rich Strauss
Arduino isn’t Keeno
I developed a great project in
Processing and then — when I went to
port it to the Arduino — it didn't fit.
Is there a utility for Processing or
some way of telling when I'm close to
the hardware limits of the Arduino?
#10132 Don Hyland
PWM Power and Short-circuit
I'm trying to design a PWM circuit
to control power to a resistive
heater strip for my camera/telescope.
Recently, my nice commercial unit let
the magic smoke out after a short on
the output side, so I'm not eager to
replace it with another of the same
The problem is I'm a complete
newbie. I'm using a 4093 for the PWM
part of the circuit and a pMOSFET
(IRF9510) for the power switching. If I
didn't want the short-circuit protection, I would be done. I've found a few
schematics online but am not sure
how to integrate them into my circuit.
Here's the schematic (Figure 1)
I've put together, however, there are
two things that bother me. First, I've
essentially glued the short-circuit
protection onto the output of the
pMOSFET which means I have
another diode drop in the output. That
seems like it should be unnecessary
and it seems like I ought to be able to
put the IRF9510 where the SK100 is,
but I'm not sure how to do that
Second, the whole thing will be
powered off a marine battery and
I'd like some input protection/isolation
of the control part to avoid the
possibility of frying the 4093 from
transients when hooking up power.
Any help is greatly appreciated!
#10133 Roland Roberts
Can Resistors Make the
I'm working on an audiophile-quality all-transistor amp. I was told
that carbon film resistors are less noisy
than wire-wound precision resistors —
which are more expensive. Could I
hear the difference in resistors? Is
there a theoretical noise difference?
#10134 Allan Perali
Audio Amp ICs
I need a good, single-source audio
amp IC for a project. The LM-386 isn't
powerful enough. Is there a 'super'
LM-386 op-amp that's also single-source (only one power connection)?
#10135 Doug Schacter
I have a box full of old lithium batteries. I know they're not supposed to
be put in the normal trash, but I don't
want to pay a fee to have 'hazardous
waste' removed. Is there a safe,
environmental friendly way for me to
dispose of the batteries that won't
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78 October 2013