Re: Nigel's IR Transmitter - a beginners tale (longish)

[Nigel Orr <nigel@xxxxxxx>]

At 09:50 03/11/00 +0000, you wrote:
>WW76 - 47uF Capacitor - =A31.27 (there must be a cheaper alternative
here =
but
>I don't know it)

It needs to be 47uF 25V, just about any electrolytic would do- Rapid
sell=20
them for 4p - 7p each.  The one you have is a tantalum, which is much=20
smaller, and in some ways better (they absorb high frequency noise better,=
=20
though they do tend to fail short-circuit, which is unhelpful!).  Given=20
that WW76 is 16V rated, it might be expected to fail (for future
reference,=
=20
it's usually worth finding the expected maximum voltage and doubling it to=
=20
pick a capacitor rating), it's probably worth replacing with a cheap=20
electrolytic instead, eg 47uF, 25V VH32 at 17p each.

> Next to consider is mounting boards, I would not even consider trying
to
>make the transmitter without a Solderless Breadboard and would suggest
it =
is
>useful to have another one for prototyping the receiver as well.

You can just do a spiders-web prototype of the receiver, solder the tips
of=
=20
the legs together and make sure nothing is shorting out, then cut the=20
soldered bits off when you come to do it properly.  But an extra prototype=
=20
board is useful!

>I bought two BZ14 - =A36.80 which have plenty of rows and columns and
have=
5=20
>screw down terminals.

I use the AG09 types more than anything, they're big enough for most
stuff,=
=20
have power rails across the top, and are cheap (2.99 each).  Currently=20
shown as out of stock, I'll refrain from further comment...

>! I have now soldered up a receiver on a JP46 Stripboard - =A30.59,
this w=
as
>the smallest board I could find and would do for at least 4 receiver
modul=
es

I usually use tripad boards, I find them faster.  Instead of there being a=
=20
continuous strip of copper, where you lose one hole for each break you
need=
=20
to make, the strip is broken into short sections, with 3 holes in each. 
As=
=20
a result, you rarely if ever need to cut strips, and can bridge a join=20
across them very easily with a component leg.  It usually results in a
more=
=20
compact circuit too.

>(by the way, what is the easiest way to cut strip boards ?).

[Junior] hacksaw

>Soldering iron and solder

25W or more powerful recommended, solder is hard to buy, as it lasts so=20
long and they keep changing the mixes!  I tend to go for something=20
'unhealthy', the self-cleaning-kinder-to-the-environment-and-your-lungs=20
ones never seem to make as good joints, and you need all the help you
can=20
get if you're just starting soldering.  But you should give some thought
to=
=20
ventilation- a small fan blowing across the work is helpful to keep the=20
fumes at bay, it certainly triggers mild asthma in me if I get too=20
'involved' in soldering over an extended period.

>Multimeter for checking resistor values (learning the colour codes
would
>have been cheaper but take much longer). Also used for checking
voltages a=
nd
>to ensure that I had not joined two tracks on the breadboard with my
>distinctly amateur soldering.

Cheap is usually good, an exception to my usual rule of save up and buy
the=
=20
best.  Most hobby uses need about 10% accuracy, and even cheap meters
can=20
manage 5% or better... ruggedness might not be so good, a rubber holster=20
can be useful, and get one with 4mm probe connections, not built-in
probes,=
=20
as they always break.

If you're likely to use any of the 'gadgets', then get a more expensive=20
one- diode testers are very useful, transistor testers are handy (though=20
you can do it all with a diode test), auto-ranging is usually a
nuisance,=20
auto-power-off is very useful, and some beep when you select a voltage=20
range when you have the probes in the current sockets, which saves a lot
of=
=20
fuse replacements!  Cheap analogue ones are available for about =A35 or
les=
s,=20
and are useful for most things (except reading resistor values) if you=20
really are on a tight budget.

>The other difficulty I had was in converting the circuit diagram to an
>actual circuit on the board.

I'll try to get a stripboard layout or a photo of mine done at some time.

>you consider that pin 5 is on the same side of the chip as 6,7 and 8
then
>the physical layout looks very different.

I'm sure there is a good reason why Cadsoft did the schematic package like
that, but it's not very helpful for stripboard design!

>  When I finally build the soldered
>circuit I will take some pictures and put them up on my site.

I'm hoping to get some photos on the web soon- I notice Boots are doing
a=20
free service of putting conventional films on the web when they develop=20
them, so as a 35mm techno-luddite (digital- ugh!), I won't have to scan=20
them myself!  Any requests- I'll probably take some pics of krone stuff,=20
and the prototype IR transmit and receiver, and maybe my X10 appliance=20
module which I'm in the process of butchering for another use...

Nigel


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