I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.

"DerbyBorn" wrote in message
2.222...
I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.

The capacitor is there to reduce sparking at the switch so prolonging it's
life.
It's best as near the switch as possible.
You could move it but it's benefits would be reduced.

On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the motor

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.

Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the motor

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.
It is almost certainly in parallel with the switch contacts so how can
you move it to the motor without routing an extra wire between the
switch and motor housing?

Tim Watts wrote in
:

On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across
the load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor




0.1pf 275vac

On 26/03/14 09:16, Bob Minchin wrote:
Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.
It is almost certainly in parallel with the switch contacts so how can
you move it to the motor without routing an extra wire between the
switch and motor housing?

That wasn't totally clear, but it could be the case.

Bob Minchin wrote in
:

Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across
the load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

As the new switch is slightly different in layout I am wondering if
the capacitor could be put across the motor terminals down at the
motor end without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.
It is almost certainly in parallel with the switch contacts so how can
you move it to the motor without routing an extra wire between the
switch and motor housing?


It was across the live and neutral of the load side of the DP switch.

Secondary question. The wires are gripped by spring claws and I quess they
need poking in. Should I lightly tin the wires to make them more rigid to
overcome the spring resistance of the grip?

On 26/03/2014 09:10, Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the motor

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.

I would have though a diode would be the more normal solution should
that be required. I would expect its there as an RF noise suppressor.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 26/03/2014 10:12, John Rumm wrote:
On 26/03/2014 09:10, Tim Watts wrote:

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

Definitely not 0.1pF. 0.1uF (100nF) would be about right though. The
OP needs to be sure to use an approved Class X AC rated component.

It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.

I would have though a diode would be the more normal solution should
that be required.

On an AC motor?!

I would expect its there as an RF noise suppressor.

Agreed. If mounted near the motor it will be more susceptible to heat,
moisture and vibration so it would need to be suitable for that
environment and mounted with a clip, not left dangling on its leadouts.

--
Andy

On Wed, 26 Mar 2014 13:38:57 +0000, Andy Wade
wrote:

On 26/03/2014 10:12, John Rumm wrote:
On 26/03/2014 09:10, Tim Watts wrote:

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

Definitely not 0.1pF. 0.1uF (100nF) would be about right though. The
OP needs to be sure to use an approved Class X AC rated component.

It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.

I would have though a diode would be the more normal solution should
that be required.

On an AC motor?!

I would expect its there as an RF noise suppressor.

Agreed. If mounted near the motor it will be more susceptible to heat,
moisture and vibration so it would need to be suitable for that
environment and mounted with a clip, not left dangling on its leadouts.

Being that far away from the switch contacts would defeat its purpose
as an RFI suppression capacitor. It has to be wired directly across
the switch contacts with a minimum of lead length for maximum benefit.
--
Regards, J B Good

On 26/03/2014 16:37, Johny B Good wrote:

Being that far away from the switch contacts would defeat its purpose
as an RFI suppression capacitor. It has to be wired directly across
the switch contacts with a minimum of lead length for maximum benefit.

Err, it'll be there as a suppressor for interference from the motor
(brushes), not from the switch contacts. I think you'll find it's
across the line, to reduce differential-mode conducted interference
being fed back into the mains. As such, and considering we're talking
about quite low frequencies here (up to 30 MHz at most), its positioning
won't be that critical.

--
Andy

On Wednesday, March 26, 2014 8:43:42 AM UTC, DerbyBorn wrote:

I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.
As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.

It'll almost certainly be a standard snubber, 0.1uF + 100ohms. 0.1pF would be completely ineffective.

Don't tin wires before putting them into connectors, solder is too soft.


NT

In article 6,
DerbyBorn writes:
Tim Watts wrote in
:

On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across
the load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

0.1pf 275vac

The component leads by themselves would be more than 0.1pF,
even if the component was just a passive lump of resin.

It will be 0.1 microfarads, most likely.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 26/03/2014 13:38, Andy Wade wrote:
On 26/03/2014 10:12, John Rumm wrote:
On 26/03/2014 09:10, Tim Watts wrote:

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

Definitely not 0.1pF. 0.1uF (100nF) would be about right though. The
OP needs to be sure to use an approved Class X AC rated component.

It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.

I would have though a diode would be the more normal solution should
that be required.

On an AC motor?!

Yes fair point ;-)

I would expect its there as an RF noise suppressor.

Agreed. If mounted near the motor it will be more susceptible to heat,
moisture and vibration so it would need to be suitable for that
environment and mounted with a clip, not left dangling on its leadouts.

ducks for cover

Or leave it off altogether, since its presumably only intended to
suppress switching RFI rather than motor running RFI.

/ducks for cover


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Wed, 26 Mar 2014 08:43:42 GMT, DerbyBorn
wrote:

I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.

Since it's wired across the load side of the original switch (100nF
not 0.1pf) wiring it directly to the motor terminals would be the
optimum placement (assuming a universal ac/dc motor with brush gear)
provided you can gain access to the motor terminals and safely wire it
in place.
--
Regards, J B Good

On Wed, 26 Mar 2014 17:26:13 +0000, Andy Wade
wrote:

On 26/03/2014 16:37, Johny B Good wrote:

Being that far away from the switch contacts would defeat its purpose
as an RFI suppression capacitor. It has to be wired directly across
the switch contacts with a minimum of lead length for maximum benefit.

Err, it'll be there as a suppressor for interference from the motor
(brushes), not from the switch contacts. I think you'll find it's
across the line, to reduce differential-mode conducted interference
being fed back into the mains. As such, and considering we're talking
about quite low frequencies here (up to 30 MHz at most), its positioning
won't be that critical.

You're right. I lost sight of the fact that the OP mentioned it being
wired across the load side of the double pole switch and got blind
sided by mentions of switch noise/arcing suppression in the subsequent
responses.

I've actually advised him to wire it directly across the motor
terminals if he can gain access and there's room for it to be safely
mounted there.
--
Regards, J B Good

On Wednesday, March 26, 2014 5:44:26 PM UTC, John Rumm wrote:
On 26/03/2014 13:38, Andy Wade wrote:
On 26/03/2014 10:12, John Rumm wrote:
On 26/03/2014 09:10, Tim Watts wrote:

I would expect its there as an RF noise suppressor.

Agreed. If mounted near the motor it will be more susceptible to heat,
moisture and vibration so it would need to be suitable for that
environment and mounted with a clip, not left dangling on its leadouts.

ducks for cover
Or leave it off altogether, since its presumably only intended to
suppress switching RFI rather than motor running RFI.
/ducks for cover

It'll reduce switch arcing, avoiding premature failure.


NT

On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across the
load side of the douple pole switch is a 0.1pf capacitor.

0.1pf Thats less that the stray couplin between the wires!

As the new switch is slightly different in layout I am wondering if the
capacitor could be put across the motor terminals down at the motor end
without any ill effects.

Probably.



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

On 26/03/2014 17:31, Andrew Gabriel wrote:
In article 6,
DerbyBorn writes:
Tim Watts wrote in
:

On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across
the load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

0.1pf 275vac

The component leads by themselves would be more than 0.1pF,
even if the component was just a passive lump of resin.

Indeed - a good deal than an "industry standard finger" even ;-)

It will be 0.1 microfarads, most likely.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Tim Watts wrote in
:

On 26/03/14 09:16, Bob Minchin wrote:
Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower.
Across the load side of the douple pole switch is a 0.1pf
capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

As the new switch is slightly different in layout I am wondering if
the capacitor could be put across the motor terminals down at the
motor end without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.
It is almost certainly in parallel with the switch contacts so how
can you move it to the motor without routing an extra wire between
the switch and motor housing?

That wasn't totally clear, but it could be the case.


Job done - I fitted it to the switch terminals - I had to modify the
housing slightly to accomodate it (the terminals were in a different
position to the original switch)
0.1 microfarads. I couldn't find the symbol and used p.

On Wed, 26 Mar 2014 23:08:10 +0000, DerbyBorn wrote:

Tim Watts wrote in
:

On 26/03/14 09:16, Bob Minchin wrote:
Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower. Across
the load side of the douple pole switch is a 0.1pf capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

As the new switch is slightly different in layout I am wondering if
the capacitor could be put across the motor terminals down at the
motor end without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.
It is almost certainly in parallel with the switch contacts so how can
you move it to the motor without routing an extra wire between the
switch and motor housing?

That wasn't totally clear, but it could be the case.


Job done - I fitted it to the switch terminals - I had to modify the
housing slightly to accomodate it (the terminals were in a different
position to the original switch)
0.1 microfarads. I couldn't find the symbol and used p.

Conventionally, one uses a lowercase 'u' for that.

--
Use the BIG mirror service in the UK: http://www.mirrorservice.org
My posts (including this one) are my copyright and if @diy_forums on
Twitter wish to tweet them they can pay me £30 a post
*lightning surge protection* - a w_tom conductor

On Wednesday, March 26, 2014 11:08:10 PM UTC, DerbyBorn wrote:
Tim Watts dionic.net wrote in
:
On 26/03/14 09:16, Bob Minchin wrote:
Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower.
Across the load side of the douple pole switch is a 0.1pf
capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

As the new switch is slightly different in layout I am wondering if
the capacitor could be put across the motor terminals down at the
motor end without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.
It is almost certainly in parallel with the switch contacts so how
can you move it to the motor without routing an extra wire between
the switch and motor housing?
That wasn't totally clear, but it could be the case.

Job done - I fitted it to the switch terminals - I had to modify the
housing slightly to accomodate it (the terminals were in a different
position to the original switch)
0.1 microfarads. I couldn't find the symbol and used p.

I trust you've not fitted a 0.1uF capacitor, if you have it will accelerate switch failure by producing switch on current spikes. If you did, maybe you can get a 100ohm series R in there.


NT

On Wed, 26 Mar 2014 14:00:58 -0700 (PDT), wrote:

On Wednesday, March 26, 2014 5:44:26 PM UTC, John Rumm wrote:
On 26/03/2014 13:38, Andy Wade wrote:
On 26/03/2014 10:12, John Rumm wrote:
On 26/03/2014 09:10, Tim Watts wrote:

I would expect its there as an RF noise suppressor.

Agreed. If mounted near the motor it will be more susceptible to heat,
moisture and vibration so it would need to be suitable for that
environment and mounted with a clip, not left dangling on its leadouts.

ducks for cover
Or leave it off altogether, since its presumably only intended to
suppress switching RFI rather than motor running RFI.
/ducks for cover

It'll reduce switch arcing, avoiding premature failure.


Actually, it will induce a modicum of welding on contact closure
which will contribute to contact erosion. Probably not to a
significant amount with a 100nF capacitor and an ac supply to minimise
the pip/crater growth effect with DC.

However, rereading the OP indicates that the capacitor is
(effectively) wired across the motor terminals to suppress brush
contact induced RFI from the universal AC/DC motor that's employed.
--
Regards, J B Good

On Thursday, March 27, 2014 1:56:31 AM UTC, Johny B Good wrote:
On Wed, 26 Mar 2014 14:00:58 -0700 (PDT), wrote:
On Wednesday, March 26, 2014 5:44:26 PM UTC, John Rumm wrote:
On 26/03/2014 13:38, Andy Wade wrote:
On 26/03/2014 10:12, John Rumm wrote:

ducks for cover
Or leave it off altogether, since its presumably only intended to
suppress switching RFI rather than motor running RFI.
/ducks for cover

It'll reduce switch arcing, avoiding premature failure.

Actually, it will induce a modicum of welding on contact closure
which will contribute to contact erosion. Probably not to a
significant amount with a 100nF capacitor

A 0.1uF 100 ohm snubber won't add enough i squared t to damage the switch. A 0.1uF capacitor alone certainly will.


and an ac supply to minimise
the pip/crater growth effect with DC.

I get the feeling you've not tried snubbing switches with 0.1uF caps.

However, rereading the OP indicates that the capacitor is
(effectively) wired across the motor terminals to suppress brush
contact induced RFI from the universal AC/DC motor that's employed.

its not a capacitor.


NT

On 26/03/14 23:08, DerbyBorn wrote:
Tim Watts wrote in
:

On 26/03/14 09:16, Bob Minchin wrote:
Tim Watts wrote:
On 26/03/14 08:43, DerbyBorn wrote:
I am replacing the trigger switch in a neighbour's lawnmower.
Across the load side of the douple pole switch is a 0.1pf
capacitor.

Possibly not 0.1pF - there's more capacitance in the wires to the
motor

As the new switch is slightly different in layout I am wondering if
the capacitor could be put across the motor terminals down at the
motor end without any ill effects.


It's probably there to suppress back-EMF spikes when the switch is
allowed to open. I don't see any issues with moving it to the motor.
It is almost certainly in parallel with the switch contacts so how
can you move it to the motor without routing an extra wire between
the switch and motor housing?

That wasn't totally clear, but it could be the case.


Job done - I fitted it to the switch terminals - I had to modify the
housing slightly to accomodate it (the terminals were in a different
position to the original switch)
0.1 microfarads. I couldn't find the symbol and used p.

Convention is to use uF if you cant find µF.

And anyway half the readers here wont work if you do because there are
different standards for 'text' and usenet is 'ascii text only' so half
of you who do NOT by default accept UTF8 wont see that as its written.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

On Thu, 27 Mar 2014 01:29:41 -0700 (PDT), wrote:

On Thursday, March 27, 2014 1:56:31 AM UTC, Johny B Good wrote:
On Wed, 26 Mar 2014 14:00:58 -0700 (PDT), wrote:
On Wednesday, March 26, 2014 5:44:26 PM UTC, John Rumm wrote:
On 26/03/2014 13:38, Andy Wade wrote:
On 26/03/2014 10:12, John Rumm wrote:

ducks for cover
Or leave it off altogether, since its presumably only intended to
suppress switching RFI rather than motor running RFI.
/ducks for cover

It'll reduce switch arcing, avoiding premature failure.

Actually, it will induce a modicum of welding on contact closure
which will contribute to contact erosion. Probably not to a
significant amount with a 100nF capacitor

A 0.1uF 100 ohm snubber won't add enough i squared t to damage the switch. A 0.1uF capacitor alone certainly will.


That was never in dispute.


and an ac supply to minimise
the pip/crater growth effect with DC.

I get the feeling you've not tried snubbing switches with 0.1uF caps.

Not in the last quarter of a century, afaicr.

However, rereading the OP indicates that the capacitor is
(effectively) wired across the motor terminals to suppress brush
contact induced RFI from the universal AC/DC motor that's employed.

its not a capacitor.

That's a startlingly definitive conclusion to draw from the OP's
description. What do you believe it is?

--
Regards, J B Good

On Thursday, March 27, 2014 5:31:16 PM UTC, Johny B Good wrote:
On Thu, 27 Mar 2014 01:29:41 -0700 (PDT), wrote:
On Thursday, March 27, 2014 1:56:31 AM UTC, Johny B Good wrote:
On Wed, 26 Mar 2014 14:00:58 -0700 (PDT), wrote:
On Wednesday, March 26, 2014 5:44:26 PM UTC, John Rumm wrote:
On 26/03/2014 13:38, Andy Wade wrote:
On 26/03/2014 10:12, John Rumm wrote:

ducks for cover
Or leave it off altogether, since its presumably only intended to
suppress switching RFI rather than motor running RFI.
/ducks for cover

It'll reduce switch arcing, avoiding premature failure.

Actually, it will induce a modicum of welding on contact closure
which will contribute to contact erosion. Probably not to a
significant amount with a 100nF capacitor

A 0.1uF 100 ohm snubber won't add enough i squared t to damage the switch. A 0.1uF capacitor alone certainly will.

That was never in dispute.

and an ac supply to minimise
the pip/crater growth effect with DC.

I get the feeling you've not tried snubbing switches with 0.1uF caps.

Not in the last quarter of a century, afaicr.

However, rereading the OP indicates that the capacitor is
(effectively) wired across the motor terminals to suppress brush
contact induced RFI from the universal AC/DC motor that's employed.

its not a capacitor.

That's a startlingly definitive conclusion to draw from the OP's
description. What do you believe it is?

I doubt a competent engineer would use a 0.1uF cap here.


NT