My Videosender popped a capacitor after the 'kids' plugged it into a 12v
supply.

The capacitor that blew is a 100uF 25v, does anyone know where i can buy
just ONE of these in the UK?

Stu.

Maplin.co.uk should sell them, will cost a couple of quid for postage
though.

I have a Maplin store a few miles away, do the stores stock all the stuff
that u see in the catalogues?

Stu.

On Wed, 13 Aug 2003 19:55:59 GMT, "stu" wrote:

Just swapping a blown cap may not fix the circuit. It might work for
an indefinate amount of time, but typically there is unseeable damage
elsewhere. Good luck.

My Videosender popped a capacitor after the 'kids' plugged it into a 12v
supply.

The capacitor that blew is a 100uF 25v, does anyone know where i can buy
just ONE of these in the UK?

Stu.

Most capacitors are married to a circuit.
Therefore if you want a SINGLE one you will have to desolder it.
Ask a TV repair shop for some old trash circuit boards and you will
likely end up with a few 100uF caps. It's ok to use one with a higher
voltage rating.
Stepan

On Wed, 13 Aug 2003 19:55:59 GMT, "stu" wrote:

My Videosender popped a capacitor after the 'kids' plugged it into a 12v
supply.

The capacitor that blew is a 100uF 25v, does anyone know where i can buy
just ONE of these in the UK?

Stu.

Yes normally, your options are to A) ring in advance, or B) fit a capacitor
of a slightly different value if they have them in stock, e.g. higher
voltage rating or slightly different capacitance.

Where are you based? I could give you one if you were local, or
alternatively, if you knocked on the door of a local electronics firm they
might give you one.

A

"stu" wrote in message
...
Maplin.co.uk should sell them, will cost a couple of quid for postage
though.

I have a Maplin store a few miles away, do the stores stock all the stuff
that u see in the catalogues?

Stu.

Yes normally, your options are to A) ring in advance, or B) fit a
of a slightly different value if they have them in stock, e.g. higher
voltage rating or slightly different capacitance.

I'll have a look around for a close match.
Why did the cap blow with a 12v supply it's rated for 25v?

Where are you based? I could give you one if you were local, or
alternatively, if you knocked on the door of a local electronics firm they
might give you one.

I'm in Glasgow, I think I'll pop out to the local Maplins and see what new
toys they have. ;-)

Stu.

Most capacitors are married to a circuit.
Therefore if you want a SINGLE one you will have to desolder it.
Ask a TV repair shop for some old trash circuit boards and you will
likely end up with a few 100uF caps. It's ok to use one with a higher
voltage rating.

Ok, so the capacitance MUST remain 100uF but the voltage can be as high as i
like, but not less than the original 25v?

Stu.

When I design stuff I stick in 100uF out of habit and without any specific
calculation of value. If I consider you application, I cannot think it is
really critical and (if it was me) would happily replace it with any
capacitor between 50uF and 150uF, and if I absolutely couldn't find anything
else, would go as low as 10uF. For your application the only ciritical
factor is not to have a voltage rating too low, only equal or larger than
the current capacitor. I think the actual value of capacitance is less
important.

When you say it popped - do you mean it literally blow up? And plugged it
into a 12V supply - what is the proper voltage AC or DC and voltage? This
may help us to understand if other things will have gone wrong. I'd be
surprised if only a capacitor was affected - did they connect the voltages
the wrong way round?

A


"stu" wrote in message
...
Most capacitors are married to a circuit.
Therefore if you want a SINGLE one you will have to desolder it.
Ask a TV repair shop for some old trash circuit boards and you will
likely end up with a few 100uF caps. It's ok to use one with a higher
voltage rating.

Ok, so the capacitance MUST remain 100uF but the voltage can be as high as
i
like, but not less than the original 25v?

Stu.

When you say it popped - do you mean it literally blow up? And plugged
into a 12V supply - what is the proper voltage AC or DC and voltage? may
help us to understand if other things will have gone wrong. I'd be
surprised if only a capacitor was affected - did they connect the voltages
the wrong way round?

The capacitor exploded, lol

The unit takes 9v AC, AFAIK they gave it 12v AC the correct way round.

Stu.

And having removed the mess - does it actually not work? I mean, lots of
circuits will "sort-of" work without the capacitors, just get a bit noisy or
lossy.

A

"stu" wrote in message
...
When you say it popped - do you mean it literally blow up? And plugged
into a 12V supply - what is the proper voltage AC or DC and voltage? may
help us to understand if other things will have gone wrong. I'd be
surprised if only a capacitor was affected - did they connect the
voltages
the wrong way round?

The capacitor exploded, lol

The unit takes 9v AC, AFAIK they gave it 12v AC the correct way round.

Stu.

And having removed the mess - does it actually not work? I mean, lots of
circuits will "sort-of" work without the capacitors, just get a bit noisy
or
lossy.

Well, I don't know to be honest.
It still lights up and appears to work with the original 9v supply, but
since I can only find one of the two 9v supplies to power the videosender I
don't know if it is actually receiving the signal.

On Thu, 14 Aug 2003 14:47:45 GMT, Stepan Novotill
wrote:

On Thu, 14 Aug 2003 09:36:22 GMT, "stu" wrote:

Your statement below is correct.

Ok, so the capacitance MUST remain 100uF but the voltage can be as high as i
like, but not less than the original 25v?

Stu.


Never go lower than rated voltage.

With electrolytics, you can go a little higher, say to the next
standard voltage (35Vdc or even 50Vdc). This has to do with the way
the capacitor develops its dialectric film during charge. (Hence the
name "electrolytic")

(Just curious - was the adaptor the kids plugeed the unit into also
reverse voltage besides being 12 vs. 9 volts?) hooking an
electrolytic up backward is guarantteed to short it out with the sort
of result you observed.)

And sorry - I live in the US. Cant help you find one.

GOod luck

You can't hook AC up backwards. no matter which way you hook it it comes
out the same, it's DC that's connected backwards. also take into
consideration if a bridge rectifier is used, the output is always
slightly more than the input.




Cliff S










"stu" wrote in
:

When you say it popped - do you mean it literally blow up? And
plugged
into a 12V supply - what is the proper voltage AC or DC and voltage?
may help us to understand if other things will have gone wrong. I'd be
surprised if only a capacitor was affected - did they connect the
voltages the wrong way round?

The capacitor exploded, lol

The unit takes 9v AC, AFAIK they gave it 12v AC the correct way round.

Stu.