Site in the UK supplying the following...

Hi there,
I'm building a small radio transmitter with instructions I received from a
friend. I'm in the UK and looking for the following. I can't find some of
the things on the list and others when I do find them there are many types
and I don't really know which one I'll need. Unless they're all pretty much
the same?

330R Resistor
6K8 Capacitor
4.7 Capacitor
1nF Capacitor (102 on it)
100 nF Capacitor (104 on it)
BC549 Transistor
Omnidirectional microphone
Variable tuning capacitor (green pot)
5 turn coil

This is the only information, component wise I've got so is it obvious to
you clever lot what specific components they are? Or would more information
be required?

If anyone could help it'd be very appreciated.

Thank you,
Jon

 

A few things: You don't give a wattage for the resistor - a standard 0.6W
will probably do it. Also, the "6K8" capacitor doesn't look right. Are you
sure it's a capacitor and not a resistor? Is the "6K8" written on its body?
It could be 6.8nF but I don't know. The "4.7" cap is probably 4.7pF. When
you buy the caps, ask for "ceramic" ones. You don't specify a capacitance
range for the variable tuning capacitor. They usually are in the pF range,
but again I'm guessing here. Omnidirectional mic of what type? There are
many types out there... Does it have two of three pins? This will give us
some clues. The 5-turn coil you probably need to make yourself by purchasing
some insulated coil wire (check the wire thickness and coil's general
shape).

Other than that, they all look like very standard components to me. Are
there any Maplin stores in your area? If yes, pop in to one of them with the
component list and they will help you out (although I wouldn't count too
much on their knowledge of electronics). Cost should be less than £5 (the
mic should be the most expensive item).

All of the sites below should have all of the components:

http://www.farnell.co.uk/ --- My favourite (min order £10, free delivery)
http://rswww.com/ --- Can order < £10 but they charge for delivery
http://www.maplin.co.uk/ --- I only visit their shop when I need sth NOW!

Hope this helps. Feel free to ask if you need more info.
Good luck with the project.

Costas
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NOW!

Would add for others in UK , Rapid:

http://www.rapidelectronics.co.uk No minimum order but £3.95 P+P below
£25

Adam

 

Hi,
Thanks for your reply, it helped a lot. That'll get me started I'm sure. I
have some more info. regarding the components.

330R Resistor (red, red, black, black) colour code
6K8 Resistor (blue, grey, black brown) colour code
The two 4.7 capacitors have 4P7 on them and are mainly grey with a black bit
on top.

I'm thinking the colour codes of the resistors are unique to that resistor
so it should be easy to ID?

Thanks again for any light you can shed on this.

Cheers,
Jon

 

You're welcome.

Your 330 Ohm resistor should be orange-orange-black-black. The colour code
you mention above is for a 220 Ohm resistor.

For the same type of resistor, the colour coding should be the same
regardless or manufacturer. The thing to note is how many colour stripes the
resistor has. Some only have three (plus the % one), so a 330 Ohm resistor
would be orange-orange-brown in this case (because the multiplier has to be
10 to give 33 x 10 = 330). With the 4-colour coding we have 330 x 1 = 330.
You can always measure them with a multimeter to make sure.

cheers,
Costas
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Standard 330 ohm resistor

Are you sure that's exactly what was specified? 6K8 means 6.8K, but
you've specified no units. I don't recall seeing a 6800uF capacitor
specified as 6K8. Maybe it's 6.8nF...

That seems to confirm that you've either been given a careless
specification or copied it incorrectly. That is almost certainly a
4.7uF (microfarad) capacitor

1nf = 1 nanofarad

100 nanofarad

OK, that's the type of transistor

That's inadequate. Is it meant to be hand-wound? If so, you need its
diameter, and what it's wound on/ Or maybe it's an air type?

With respect, are you confident of being able to build this
successfully, even when you know what the parts are?

 

Mmm... close but no sigar.
Try this:

http://www.okaphone.nl/calc/resistor.shtml?ohm=330
http://www.okaphone.nl/calc/resistor.shtml?ohm=6K8

CU Hans

 

No CIGAR for you either Hans. Ever heard of a 5 or 6 band resistor
colour code?

Try that URL again, this time use the first drop down menu as well and
you'll find that Costas was perfectly correct.

niftydog

 

Ehm... Yes. But as far as I can see, only four where mentioned...

Only when you add a fifth colour for the tolerance?
Or do you think it makes sense to specify a value with three digits
when it has a tolerance of twenty percent?

CU Hans