On Mon, 28 Jul 2003 07:02:53 GMT, (John Crighton)
wrote:

On Sun, 27 Jul 2003 22:33:48 +0100, Paul Burridge
wrote:


How did you go with Win's soft start motor controller?

Currently under construction...
--

Hello Paul,
you are dragging the anchor a bit. That was months ago! :-)

Have a look here
http://www.ife.tugraz.at/datashts/nsc/h7912.pdf

You'll have to forgive me here, John, as i'm battling with a duff
display on the computer I'm using at the moment and I was only able to
glimpse the data for a few seconds, but this chip doesn't seem to be
suitable for 40Mhz FM, does it? I'm sure your general solution to the
problem is an excellent one, though, if a suitable chip can be found.
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill

On Mon, 28 Jul 2003 07:02:53 GMT, (John Crighton)
wrote:

On Sun, 27 Jul 2003 22:33:48 +0100, Paul Burridge
wrote:


How did you go with Win's soft start motor controller?

Currently under construction...
--

Hello Paul,
you are dragging the anchor a bit. That was months ago! :-)

Have a look here
http://www.ife.tugraz.at/datashts/nsc/h7912.pdf

This also looks a possibility:

http://w1.859.telia.com/~u85920178/use/rc-prop.htm

Might be a contender for the next 'bot, possibly?
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill

On Mon, 28 Jul 2003 07:02:53 GMT, (John Crighton)
wrote:

On Sun, 27 Jul 2003 22:33:48 +0100, Paul Burridge
wrote:


How did you go with Win's soft start motor controller?

Currently under construction...
--

Hello Paul,
you are dragging the anchor a bit. That was months ago! :-)

Have a look here
http://www.ife.tugraz.at/datashts/nsc/h7912.pdf

This also looks a possibility:

http://w1.859.telia.com/~u85920178/use/rc-prop.htm

Might be a contender for the next 'bot, possibly?
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill

"Paul Burridge" wrote in message
...
On Mon, 28 Jul 2003 13:20:27 GMT, (John Crighton)
wrote:

The rich guy is stunting around and decides to buzz
me at low level about 20 feet above the ground.
His model flies over me and then nose dives into
the ground near by. I could here his servos twitching
away as I walked past the wreckage.
After I retrieved my model and switched off my
transmitter, I stopped by the little gathering at the
wreck site. The rich guy was operating his servos OK
and scratching his head. " I spend thousands on
my model and that ******* John Crighton comes
here every weekend with 50 dollars worth of homebuilt
junk and flies. It just isn't fair." "Moan...grumble..moan."
I didn't try to explain that his receiver got swamped. His
mates put the crash down to pilot error at low level, and
that was that.

John, what in your experience causes this 'servo-twitching'? I've
observed it myself at close hand many times. The last time it
happened, we cured it by isolating the die-cast box the rx was mounted
in from the chassis. I still can't figure out why this worked, as I'd
have thought grounding it *ought* to solve the problem. But in this
instance, grounding it *created* the problem and isolating it solved
it! Sometimes when I see those servos behaving like they've got a mind
of their own it almost makes me believe in the supernatural.

R/C servos are EXTREMELY sensitive to trash on the power supply leads.
Grounding the box probably coupled some trash into the ground lead to the
servo.

I don't know what you have in your system, but I'd start by investing in a
few small 250 uF (nominal) capacitors and put them directly across the servo
supply leads. Use Y-harnesses to hook them in if you don't feel like
modifying a cable.

"Paul Burridge" wrote in message
...
On Mon, 28 Jul 2003 13:20:27 GMT, (John Crighton)
wrote:

The rich guy is stunting around and decides to buzz
me at low level about 20 feet above the ground.
His model flies over me and then nose dives into
the ground near by. I could here his servos twitching
away as I walked past the wreckage.
After I retrieved my model and switched off my
transmitter, I stopped by the little gathering at the
wreck site. The rich guy was operating his servos OK
and scratching his head. " I spend thousands on
my model and that ******* John Crighton comes
here every weekend with 50 dollars worth of homebuilt
junk and flies. It just isn't fair." "Moan...grumble..moan."
I didn't try to explain that his receiver got swamped. His
mates put the crash down to pilot error at low level, and
that was that.

John, what in your experience causes this 'servo-twitching'? I've
observed it myself at close hand many times. The last time it
happened, we cured it by isolating the die-cast box the rx was mounted
in from the chassis. I still can't figure out why this worked, as I'd
have thought grounding it *ought* to solve the problem. But in this
instance, grounding it *created* the problem and isolating it solved
it! Sometimes when I see those servos behaving like they've got a mind
of their own it almost makes me believe in the supernatural.

R/C servos are EXTREMELY sensitive to trash on the power supply leads.
Grounding the box probably coupled some trash into the ground lead to the
servo.

I don't know what you have in your system, but I'd start by investing in a
few small 250 uF (nominal) capacitors and put them directly across the servo
supply leads. Use Y-harnesses to hook them in if you don't feel like
modifying a cable.

On Mon, 28 Jul 2003 22:24:11 +0100, Paul Burridge
wrote:

On Mon, 28 Jul 2003 13:20:27 GMT, (John Crighton)
wrote:

The rich guy is stunting around and decides to buzz
me at low level about 20 feet above the ground.
His model flies over me and then nose dives into
the ground near by. I could here his servos twitching
away as I walked past the wreckage.
After I retrieved my model and switched off my
transmitter, I stopped by the little gathering at the
wreck site. The rich guy was operating his servos OK
and scratching his head. " I spend thousands on
my model and that ******* John Crighton comes
here every weekend with 50 dollars worth of homebuilt
junk and flies. It just isn't fair." "Moan...grumble..moan."
I didn't try to explain that his receiver got swamped. His
mates put the crash down to pilot error at low level, and
that was that.

John, what in your experience causes this 'servo-twitching'?
In that incident with the rich guy, he was a few hundred yards
away from his model and my transmitter, only 20 feet away. even
though it was on a different channel upset his signal. Therefore
his servos twitched and his model crashed.

I've observed it myself at close hand many times.

Waving a transmitter with a fully extended antenna beside
the model will cause a bit of servo twitching. The signal
is too strong. That is why you see people doing close
range testing with the antenna retracted.

The last time it
happened, we cured it by isolating the die-cast box the rx was mounted
in from the chassis. I still can't figure out why this worked, as I'd
have thought grounding it *ought* to solve the problem.

I would have thought that grounding the RX to the box would
be good practice also.
Not having a circuit to guide you, maybe you were grounding
a spot on the PCB that should not be grounded.

But in this
instance, grounding it *created* the problem and isolating it solved
it! Sometimes when I see those servos behaving like they've got a mind
of their own it almost makes me believe in the supernatural.

You got some good advice from John R Strohm in regards
to fitting decoupling capacitors across the servo supply leads.

I am assuming that your R/C gear is operating from its
own battery supply not the main driving motor supply.
Using the same battery for the radio and main driving
motors could cause servo twitching.

Pity there isn't one of these fighting robot clubs
here in Sydney. I would like to have a go.

Paul you will have to put some pictures up
somewhere so we can have a look.

Regards,
John Crighton
Sydney

On Mon, 28 Jul 2003 22:24:11 +0100, Paul Burridge
wrote:

On Mon, 28 Jul 2003 13:20:27 GMT, (John Crighton)
wrote:

The rich guy is stunting around and decides to buzz
me at low level about 20 feet above the ground.
His model flies over me and then nose dives into
the ground near by. I could here his servos twitching
away as I walked past the wreckage.
After I retrieved my model and switched off my
transmitter, I stopped by the little gathering at the
wreck site. The rich guy was operating his servos OK
and scratching his head. " I spend thousands on
my model and that ******* John Crighton comes
here every weekend with 50 dollars worth of homebuilt
junk and flies. It just isn't fair." "Moan...grumble..moan."
I didn't try to explain that his receiver got swamped. His
mates put the crash down to pilot error at low level, and
that was that.

John, what in your experience causes this 'servo-twitching'?
In that incident with the rich guy, he was a few hundred yards
away from his model and my transmitter, only 20 feet away. even
though it was on a different channel upset his signal. Therefore
his servos twitched and his model crashed.

I've observed it myself at close hand many times.

Waving a transmitter with a fully extended antenna beside
the model will cause a bit of servo twitching. The signal
is too strong. That is why you see people doing close
range testing with the antenna retracted.

The last time it
happened, we cured it by isolating the die-cast box the rx was mounted
in from the chassis. I still can't figure out why this worked, as I'd
have thought grounding it *ought* to solve the problem.

I would have thought that grounding the RX to the box would
be good practice also.
Not having a circuit to guide you, maybe you were grounding
a spot on the PCB that should not be grounded.

But in this
instance, grounding it *created* the problem and isolating it solved
it! Sometimes when I see those servos behaving like they've got a mind
of their own it almost makes me believe in the supernatural.

You got some good advice from John R Strohm in regards
to fitting decoupling capacitors across the servo supply leads.

I am assuming that your R/C gear is operating from its
own battery supply not the main driving motor supply.
Using the same battery for the radio and main driving
motors could cause servo twitching.

Pity there isn't one of these fighting robot clubs
here in Sydney. I would like to have a go.

Paul you will have to put some pictures up
somewhere so we can have a look.

Regards,
John Crighton
Sydney

On Mon, 28 Jul 2003 22:52:21 +0100, Paul Burridge
wrote:

Have a look here
http://www.ife.tugraz.at/datashts/nsc/h7912.pdf

You'll have to forgive me here, John, as i'm battling with a duff
display on the computer I'm using at the moment and I was only able to
glimpse the data for a few seconds, but this chip doesn't seem to be
suitable for 40Mhz FM, does it? I'm sure your general solution to the
problem is an excellent one, though, if a suitable chip can be found.
--

Hello Paul,
under Features on page 1 it says 50KHz to 72 MHz
but not FM. I forgot about that. My mistake.
OK we'll keep looking for something that suits your
FM transmitter.

Or find, beg, borrow, "buy used," or build an ordinary
AM R/C transmitter. Ten quid should get you an old
style metal cased Futaba transmitter.
A model shop gave me the circuit diagram decades
ago of an old JR brand transmitter that I bought off
them in dud condition, cheap. Keep looking. That
model shop/sanwa agency are a bit mean that is why
I said dump their product.
Stick with brands that will offer support and circuits.

There is plenty of info with that LM1872 chip,
that is what makes it attractive to use.

Have Fun,
John Crighton
Sydney

On Mon, 28 Jul 2003 22:52:21 +0100, Paul Burridge
wrote:

Have a look here
http://www.ife.tugraz.at/datashts/nsc/h7912.pdf

You'll have to forgive me here, John, as i'm battling with a duff
display on the computer I'm using at the moment and I was only able to
glimpse the data for a few seconds, but this chip doesn't seem to be
suitable for 40Mhz FM, does it? I'm sure your general solution to the
problem is an excellent one, though, if a suitable chip can be found.
--

Hello Paul,
under Features on page 1 it says 50KHz to 72 MHz
but not FM. I forgot about that. My mistake.
OK we'll keep looking for something that suits your
FM transmitter.

Or find, beg, borrow, "buy used," or build an ordinary
AM R/C transmitter. Ten quid should get you an old
style metal cased Futaba transmitter.
A model shop gave me the circuit diagram decades
ago of an old JR brand transmitter that I bought off
them in dud condition, cheap. Keep looking. That
model shop/sanwa agency are a bit mean that is why
I said dump their product.
Stick with brands that will offer support and circuits.

There is plenty of info with that LM1872 chip,
that is what makes it attractive to use.

Have Fun,
John Crighton
Sydney

On Mon, 28 Jul 2003 23:07:59 +0100, Paul Burridge
wrote:


Have a look here
http://www.ife.tugraz.at/datashts/nsc/h7912.pdf

This also looks a possibility:

http://w1.859.telia.com/~u85920178/use/rc-prop.htm

Might be a contender for the next 'bot, possibly?
--

Hello Paul,
yes it does. That is a great site. Harry gives you
the circuit, the artwork and tells you how he makes
his printed circuit boards.
Harry explains that he has managed to use that
little AM Rx on FM also.
I think you plenty of info now Paul.
Have Fun,
John Crighton
Sydney