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Does anyone use a separate choke any more?


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#1 Alchemist

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Posted 05 July 2019 - 03:14 PM

The good old fashion choke?

 

Some years ago, my wife was using a choke I made with some wire wound around a PVC pipe scrap, to assist in making the car she was using more "drivable" for her.

 

It had one of Sir John H's "wound up" motor, so initially it was "trigger happy".

 

Anyway, as much as the choke proved to help her driving, she told me that it was "ugly and big" (hahaha) and that I needed to make her one that was "NOT!".  LOL

 

 

 

So, I found this just now, as I pulled her slot car box down from the rafters.

 

I fabricated this "Retro-mod" choke approximately not too long after she made that comment, and wanted to inquire if anyone still uses these things.

 

Seems as though they are no longer a need because the newer controllers have built in chokes.

 

Here are some pictures.

 

Top View looking down

Controller Choke_1.jpg

 

Front View

Controller Choke_2.jpg

 

Side View

Controller Choke_3.jpg

 

Small and compact (footprint is 3.5" x 4.5")

Controller Choke_4.jpg

 

 

It fit snugly inside her slot car box drawer, and most importantly she thought it was cute!  LOL

 

Thank you for viewing!

 

Ernie


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#2 Bill from NH

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Posted 05 July 2019 - 03:27 PM

Ernie, some 1/32 & 1/24 eurosport racers use them, not everybody running those classes have controllers with the built-in chokes. You'll still find them in some wing car classes too. You can buy a work box to pretty it up with her favorite colors & monogram it with her name or initials.


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#3 SpeedyNH

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Posted 05 July 2019 - 04:02 PM

wow, a real inductive choke!  nice.

most people just use a coil of wire. I wound mine on a piece of steel bar stock inside a small mushroom can with a 16-pos. HD rotary switch on top for the taps. what I should have done was use an E-I core with a paper gap but I wanted to fit it in the can. it was more of a resistor than a 'choke'.  

those look like those ferrite cores. are they rated for low frequencies? 

Speedy


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#4 drrufo

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Posted 05 July 2019 - 04:05 PM

I just bought one from a racer in NorCal. It looks very much like the one pictured. I am thinking about making them to go with my controllers.

 

John Andersen


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#5 bbr

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Posted 05 July 2019 - 04:07 PM

there are two types of chokes used these day, wire and voltage.

ES guys use both, wire chokes mainly used by wing racers.

the coolest wire chokes are the chokemaster (Rudock) and a similar design by Difalco, they both use relays to select the choke positions

 

Difalco remote wire choke:

Untitled.png

 

Rudock:

Untitled.png


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#6 Tim Neja

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Posted 05 July 2019 - 07:37 PM

I have an old Koford choke---the little "barrel" of wire!!  It works fine-- is very compact and handy when you need one!!


She's real fine, my 409!!!

#7 Alchemist

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Posted 05 July 2019 - 09:53 PM

SpeedyNH said:   are they rated for low frequencies? 

Hi Steve,

 

I could not tell you, because I purchased the ferrite cores and wound them myself years ago, but at least it works.

 

I just bought one from a racer in NorCal. It looks very much like the one pictured. I am thinking about making them to go with my controllers.

Hi John,

 

If it has more connector lugs on it, that one was mine that I gave to Frank of Slot Car Raceway in Rohnert Park, and he had it on display for sale.       It was a larger version of my wife's choke.

 

Perhaps it was sold prior to the closing of the track.

 

Thanks for sharing that info because I didn't have an opportunity to ask Frank what happened to it!

 

Mike,

 

Thanks for sharing those pictures - appreciate it!

 

Ernie


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#8 Ecurie Martini

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Posted 06 July 2019 - 01:13 AM

As a long time electronics hobbyist (back to the vacuum tubes days) I have been puzzled by the use of the term "choke" and its application to slot racing. I am very familiar with the terms "reactance" and "impedance" and would note in passing that they apply to AC, not DC circuits.  In a DC circuit, only the resistance component of a choke, the simple resistance of X feet of wire is applicable.

 

I can think of only two cases in slot racing where a "choke" function (other than the aforementioned resistance of the wire) might apply.

 

1.  If the track power supply is an unfiltered rectified AC system, there will be significant "ripple" in the output.  If it is filtered, this ripple will be reduced as a function of the effectiveness of the filter but will rarely reach zero.  The power then will have some AC component and the addition of a"choke" will reduce this, lowering the peak voltage.  In the case of a battery system, the output is pure DC with no ripple component and, in a steady state situation, the choke will be a simple resistance. I would thus expect the action of a choke would be different in these two instances.

 

2.  In (1) above reference was made to a steady state situation, i.e. flat out on a long straight.  There are other, non steady state situations.  The degree to which a choke will affect power delivery is a function of the magnitude and rate of change of applied power. As an example, going from zero to full power  very quickly (slam on the throttle or push a full power bypass switch) will briefly mimic the voltage change of the first part of an AC cycle and the wave shape will not be a square wave but will be a sloped, slightly curving wave form. Other changes, if they occur very rapidly, (small fractions of a second) will share some of this characteristic.

 

There remains, of course, the question of the degree to which these waveform variation are followed by (or damped by) the mechanical inertia of the armature so I end up asking: Do chokes really choke?

 

EM


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#9 Alchemist

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Posted 06 July 2019 - 01:33 AM

Hi Alan,

 

Hope all is well!

 

I too, have been puzzled by the term "choke".

 

To this day, I'm still confused, but lots of racers seem to understand what it is - for me, it serves its need but I have no idea what else to call the device!

 

Thanks for sharing!

 

Ernie


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#10 Greg Erskine

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Posted 06 July 2019 - 01:42 AM

hi Ecurie Martini,

 

I am curious too. I always though chokes were inductors!

 

The Koford "choke" I have is just a switch with multiple lengths of resistance wire.

 

 


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#11 Bill from NH

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Posted 06 July 2019 - 06:33 AM

If you know when to use a choke & how to use it, isn't it immaterial what you want to call it? :)


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#12 drrufo

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Posted 06 July 2019 - 07:14 AM

The choke I bought was a mate to the one shown. I don’t want to steal a design so I might not try to make them.

It is too bad because it seems to be a good design

John andersen


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#13 smichslot

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Posted 06 July 2019 - 08:25 AM

Resistance is the key

 

A lot of old "chokes" was made by wrapping a length of wire around a tube made of a material that was able to resists heat, i.e. aluminum, typically with a diameter of 1"/25mm.

The created a coil that both a had an inductance and a resistance.

A 1mm2 of wire with the lenght of 1 m (3') has a resistance of 0,017 ohm, which is appx 0,006 ohm (6 milliohm)/foot, and 3 m of this wire would have a resistance of 0,06 ohm (60 milliohm). The inductance of these windings will not be very large, and will not have any significant effect on the motors we use.

The resistance will, though, and since the wires can handle a lot of current short term they a popular for making chokes.

The inductance can be increased by adding iron-cores, but small cores are unable to support significant induction-increases. It does not take many amp's in the coil before the cores goes into saturation, just a couple of amperes.

And that is why Kopriwa used pure resistances in his classic controllers with built-in choke. The switching was done with relais.

 

Depending on the type of motor/car you want to "choke down" you might be able to get away with using a small resistor.

A 3W resistor with a resistance of 0,015 ohm (2 feet of "choke") can handle a current of 14A, which will be fine for many Eurosport cars, and also wing-cars with "softer" motors, i.e. G12.

 

Steen


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#14 Ramcatlarry

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Posted 06 July 2019 - 08:38 AM

Choke/restrictor of current.  Buffer to wheel spin at first punch of the trigger, varies with motor used.


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#15 Alchemist

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Posted 06 July 2019 - 10:10 AM

 

 

The choke I bought was a mate to the one shown. I don’t want to steal a design so I might not try to make them.

It is too bod because it seems to be a good design

John andersen 

Hi John,

 

That is very considerate of you  . . .  you're a scholar and a gentleman!

 

As I mentioned, I had made one for myself, and now you say you own it;   if it is your desire is to produce a similar design - I say "Do it!".

 

It's nice that someone likes my design enough to replicate it.

 

If I may ask that you please, at least, give me a little credit for the inspiration.

 

Thanks John!

 

Ernie


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#16 Bill from NH

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Posted 06 July 2019 - 10:27 AM

The choke I bought was a mate to the one shown. I don’t want to steal a design so I might not try to make them.

It is too bod because it seems to be a good design

John andersen

 

John, I have no idea who made the first ones. Bill Bugenis, of Brooklyn, NY, was building & selling wire wound ferrite chokes for scale racing some 10-12 yrs. ago. I don't know if he still makes them, but his were the first i saw. 


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#17 Alchemist

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Posted 06 July 2019 - 10:52 AM

 

Ernie, some 1/32 & 1/24 eurosport racers use them, not everybody running those classes have controllers with the built-in chokes. You'll still find them in some wing car classes too. You can buy a work box to pretty it up with her favorite colors & monogram it with her name or initials.

Hi Bill,

 

I made her - her own "workbox" in her favorite color.

 

Purple

Fran's Box_1.jpg

Fran's Box_2.jpg

Fran's Box_3.jpg

 

Fits nicely in the drawer

Fran's Box_4.jpg

 

And even made her a cover to protect the finish while in transit

Fran's Box_5.jpg

 

Thank you.

 

Ernie


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#18 gotboostedvr6

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Posted 06 July 2019 - 10:57 AM

I have a new koford choke I'd sell cheap if anyone is interested.

$85 plus the ride
post-4063-0-19158900-1553691337.jpg
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#19 Alchemist

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Posted 06 July 2019 - 11:07 AM

That looks so efficient to use - I like it!

 

Thanks for sharing that picture David!

 

Someone's gonna pick that up.

 

Ernie


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#20 Alchemist

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Posted 06 July 2019 - 11:41 AM

 

John, I have no idea who made the first ones. Bill Bugenis, of Brooklyn, NY, was building & selling wire wound ferrite chokes for scale racing some 10-12 yrs. ago. I don't know if he still makes them, but his were the first i saw. 

 

Hi Bill,

 

I appreciate that you mentioned this and perhaps what I said about "my design" could be miscomprehended, so, I wish to clarify.

 

I was not implying that I was the first person/creator to design a toroidal choke.

 

When I said "my design", I was referring to the methodology/layout of materials  used;  an acrylic base, polycarbonate angle, terminal crimp lugs, internally threaded aluminum rod and metal brackets that were amalgamated to produce my choke.

 

I'm presuming this is what John meant, and what I understood - perhaps he'll voice his input.

 

Perhaps I should have stated that this was how I chose to build my own "choke".

 

In any case, thank you Bill for sharing that.

 

Thank you.

 

Ernie

 


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#21 Rob Voska

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Posted 06 July 2019 - 11:48 AM

Interesting switch type on OWH.

 

In my mind a choke is simply a wire restrictor.  More feet of wire = more restriction. 

Smaller wire more restriction.  Larger wire less restriction.

For flat track racing I have been just wrapping the wire around a piece of wood or plastic like a card.

I try to do a neat job and even gave up on the odd tap lengths.  Just make a tap every 5 ft. 

So I can have 5, 10, 15, 20, 25 ft of wire.  The controller will do the rest.

 

I I ran wings I would do them closer together.

 

Sure you can figure out the resistance of the wire per foot and all that, wrap it around magnets or iron cores but when they generate heat all that goes out the window anyhow.



#22 SoCal Bill

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Posted 06 July 2019 - 12:00 PM

As a long time electronics hobbyist (back to the vacuum tubes days) I have been puzzled by the use of the term "choke" and its application to slot racing. I am very familiar with the terms "reactance" and "impedance" and would note in passing that they apply to AC, not DC circuits.  In a DC circuit, only the resistance component of a choke, the simple resistance of X feet of wire is applicable.

 

I can think of only two cases in slot racing where a "choke" function (other than the aforementioned resistance of the wire) might apply.

 

1.  If the track power supply is an unfiltered rectified AC system, there will be significant "ripple" in the output.  If it is filtered, this ripple will be reduced as a function of the effectiveness of the filter but will rarely reach zero.  The power then will have some AC component and the addition of a"choke" will reduce this, lowering the peak voltage.  In the case of a battery system, the output is pure DC with no ripple component and, in a steady state situation, the choke will be a simple resistance. I would thus expect the action of a choke would be different in these two instances.

 

2.  In (1) above reference was made to a steady state situation, i.e. flat out on a long straight.  There are other, non steady state situations.  The degree to which a choke will affect power delivery is a function of the magnitude and rate of change of applied power. As an example, going from zero to full power  very quickly (slam on the throttle or push a full power bypass switch) will briefly mimic the voltage change of the first part of an AC cycle and the wave shape will not be a square wave but will be a sloped, slightly curving wave form. Other changes, if they occur very rapidly, (small fractions of a second) will share some of this characteristic.

 

There remains, of course, the question of the degree to which these waveform variation are followed by (or damped by) the mechanical inertia of the armature so I end up asking: Do chokes really choke?

 

EM

If you think a little further you will realize that Slot Cars do not use steady state DC. The voltage goes up and down sometimes rapidly. Like half an AC wave in a sense.  The electronic voltage reducing chokes actually do react more like a straight voltage reducer. There is some inductance with a wire choke wrapped on a metal coil. You can feel the difference. The wire chokes sag a little more at the beginning so you do not have to limit the upper voltage reached quite as much. More starting control with a little more top end retained. Subtle but noticeable. 


Bill Fagan

#23 drrufo

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Posted 06 July 2019 - 12:40 PM

I like the Koford design but it seems too heavy to me. The pictured choke ( the Ernie Choke) might be the best for its size, I have repaired controllers that had 12 feet of wire just wrapped and tied with a tie wrap. 

I don't know how much of a demand there is for a choke but I get requests for Choke Masters all the time . The Ernie Choke might be easier and cheaper to build. 

 

John Anndersen


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#24 NJ Racer

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Posted 06 July 2019 - 12:51 PM

Built for me by well known ISRA Racer & owner of Grand Prix Model Raceway, Schenectady,NY. Lou Pirro Wound for me for Open 12 and B Production. Mint !

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#25 Ecurie Martini

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Posted 06 July 2019 - 02:52 PM

If you think a little further you will realize that Slot Cars do not use steady state DC. The voltage goes up and down sometimes rapidly. Like half an AC wave in a sense.  The electronic voltage reducing chokes actually do react more like a straight voltage reducer. There is some inductance with a wire choke wrapped on a metal coil. You can feel the difference. The wire chokes sag a little more at the beginning so you do not have to limit the upper voltage reached quite as much. More starting control with a little more top end retained. Subtle but noticeable. 

 Yes, that is the point I made in (2).  It will damp the rate of change of the voltage seen by the motor to a degree dependent on the rate of change,  So far as more "top end' - that cannot exceed the supply voltage and, in the limit, will be reduced by the resistance of the braid, track wiring, controller wiring, power supply (internal) and the back EMF of the motor.

 

Now, I am not familiar with the acceleration curves of commercial track cars but, for example, if a car is at full power at 10% of the straight and at full speed at 30%, the only effect of the choke will be a very slight reduction in that power and speed due to its DC resistance with one possible exception:  DC motors in general do not like AC so, if there some 60Hz ripple present in the power source (see case 1) and the choke reduces that, the heating effect of the ripple will be reduced and a slightly cooler armature will have a lower resistance and correspondingly higher current flow.

 

An observation/question:  Audio speakers are a form of a motor and typically use an external circular surrounding magnet and an internal pole piece.  In order to maximize the number of turns of wire within the ideally smallest gap, the voice coils will, in high quality applications, be wound with flat (rectangular cross section) wire on edge or hexagonal wire to achieve closest packing.  Has something similar ever been tried in slot cars?

 

EM


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