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PenrithBeacon

Adventures In Radio Control

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4 hours ago, Robin2 said:

 

 

They are cheap and seem to work very well with a multi-turn pot to set the voltage, but something considerably smaller would be nice.

 

...R

 

I've used these 

https://www.ebay.co.uk/itm/DC-DC-2-5V-15V-To-3-3V-4-2V-5V-9V-12V-Automatic-Buck-Boost-Step-Up-Down-Module/283343304564?ssPageName=STRK%3AMEBIDX%3AIT&var=584275209112&_trksid=p2060353.m2749.l2649

They are considerably smaller than the "blue" ones but have to be ordered for the required output voltage. But they are so cheap it's easy to order a selection to keep in stock.

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1 hour ago, Corbs said:

Ahaaa interesting. Polulu do an adjustable one but the sizes are in cubits for some reason:

https://www.pololu.com/category/132/step-up-voltage-regulators

 

LOL, apparently they still use feet and inches over there. The metric dimensions are on the product page. I seem to remember that NASA lost a very expensive planetary probe because a fuel valve stuck closed. Nasa use metric and the contractor used imperial, doh!, there is no exact conversion

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34 minutes ago, wasdavetheroad said:

 

LOL, apparently they still use feet and inches over there. The metric dimensions are on the product page. I seem to remember that NASA lost a very expensive planetary probe because a fuel valve stuck closed. Nasa use metric and the contractor used imperial, doh!, there is no exact conversion

 

Yes , we use both systems "Over Here" :)  That's why I can send etch drawings to the UK and not not have them printed 25.4 times too small.

OTOH, a "thou" is conveniently more precise than 0.1 mm when drawing small parts.

 

Andy (one of the "they") . 

.

 

 

 

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9 hours ago, wasdavetheroad said:

 

 there is no exact conversion

Yes there is. The official definition of an inch is 25.4 millimetres (from my US physics text book)

 

...R

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11 hours ago, Corbs said:

Ahaaa interesting. Polulu do an adjustable one but the sizes are in cubits for some reason:

https://www.pololu.com/category/132/step-up-voltage-regulators

Thanks. The fixed 5v version would meet my need and it is significantly smaller than what I have. But it also seems a lot more expensive. I wonder if any UK supplier stocks them?

 

I will keep it in mind. For the moment I need a battery trailer anyway and it has been easy to use the step-up module as the chassis for the trailer with a 3D printed frame and a couple of Peco wagon wheels glued on. I am working on the basis that nobody looks at the technology of the chassis :)

 

...R

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4 hours ago, Robin2 said:

Yes there is. The official definition of an inch is 25.4 millimetres (from my US physics text book)

 

...R

Yes, 1 inch = 25.4mm. As I understand it this was adopted to lock the US system into the international metric one. It might not work the other way round though. Converting 25mm to US gives you 0.9842519" and my calculator ran out of digits.

 

The NASA incident was probably caused by quality control issues, someone should have checked with a laser that those components were within tolerance.

 

The USA converting to metric would cost a LOT of dollars for little advantage.

 

edit - I am of the generation that is comfortable with both, younger colleagues would look confused when I was marking out 7" x 50mm

Edited by wasdavetheroad

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4 hours ago, Robin2 said:

Thanks. The fixed 5v version would meet my need and it is significantly smaller than what I have. But it also seems a lot more expensive. I wonder if any UK supplier stocks them?

 

I will keep it in mind. For the moment I need a battery trailer anyway and it has been easy to use the step-up module as the chassis for the trailer with a 3D printed frame and a couple of Peco wagon wheels glued on. I am working on the basis that nobody looks at the technology of the chassis :)

 

...R

From the  pololu site they are discontinuing that series of regulators but you might find some online

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1 hour ago, wasdavetheroad said:

From the  pololu site they are discontinuing that series of regulators but you might find some online

Thanks for that, but I have no immediate need of them.

 

...R

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1 hour ago, wasdavetheroad said:

Converting 25mm to US gives you 0.9842519" and my calculator ran out of digits.

There won't be many machine tools that can work to that level of precision.

 

...R

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6 hours ago, Robin2 said:

Thanks. The fixed 5v version would meet my need and it is significantly smaller than what I have. But it also seems a lot more expensive. I wonder if any UK supplier stocks them?

 

I will keep it in mind. For the moment I need a battery trailer anyway and it has been easy to use the step-up module as the chassis for the trailer with a 3D printed frame and a couple of Peco wagon wheels glued on. I am working on the basis that nobody looks at the technology of the chassis :)

 

...R

 

1/25.4 In reverse, 1 mm = 0.0394" handles most everyday railway modelling.

 

(Good) Working chassis suspension is what makes models realistically glide, rather than bump and bounce like toys. For me personally, slow smooth realistic movement, giving the impression of the massive weight and inertia of the prototype, is the Number 1 goal of my modelling.

 

(plus the perfect pick up saves the chain saw complication of using battery power :D)

 

Andy

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3 hours ago, Andy Reichert said:

 

(plus the perfect pick up saves the chain saw complication of using battery power )

 

For me batteries save the hassle of cleaning track and wheels and, indeed, dirty track (e.g. matt paint) gives much better traction.

 

Not to mention the avoidance of frog wiring.

 

But each to his own.

 

...R

Edited by Robin2
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I like it as it gives me locos that will run for at least a day between charges at exhibition, and are totally reliable.

 

This is with at least 650mAh batteries, and 5-6v planetary gearmotors though..... using a RTF drive I wouldn't expect the same sort of duration.

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42 minutes ago, Giles said:

I like it as it gives me locos that will run for at least a day between charges at exhibition, and are totally reliable.

 

This is with at least 650mAh batteries, and 5-6v planetary gearmotors though..... using a RTF drive I wouldn't expect the same sort of duration.

For me the size of battery is dependent on how much the loco works in the operating session. For example my sessions last no more than 3 hours and a large pacific loco pulling a 12 coach train at speed consumes about 500mA . While idling in the fiddle yard it consumes 20mA. Half an hours running (over 50 circuits of the layout) consumes 250mAh and two and a half hours idling consumes 50mAh. So a 300mAh battery is needed. In my large locos I use a 2S battery so theoretically a pair of 160mAh will do the job. I use 190mAh or 250mAh. Actually a pair of 320mAh is just fine as the locos don't run for anywhere near half an hour. 

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I'm getting on with a new Comet chassis for the Jinty, I'm a slow worker!

The idea here is for a P4 chassis using a N20 12V motor. The driven axle is rigid, the middle axle is sprung and the third axle rocks.

 

IMG_20191214_165349.jpg

IMG_20191214_151119.jpg

IMG_20191214_151152.jpg

The top photo shows the rocking arrangements. The pivot bar (1mm nickel silver) doesn't bear directly on the axle but on a collar made from two top hat bearings soldered together.

The middle photo shows the chassis just soldered up and the lower one the motor and the motor mount I found on eBay. I have found that if I cut off the lugs the mount and motor will just slide inside the frames on this P4 chassis. 00 and EM modellers will have to mount these on their sides because of the more limited space between the frames.

More later as work progresses.

Cheers

Edited by PenrithBeacon
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10 hours ago, PenrithBeacon said:

I'm getting on with a new Comet chassis for the Jinty, I'm a slow worker!

The idea here is for a P4 chassis using a N20 12V motor. The driven axle is rigid, the middle axle is sprung and the third axle rocks.

 

 

Why the choice of 12v motor, given that N20's come with a range of motor voltages ?   By going for a lower voltage motor, you don't need the voltage multiplier circuitry.

The motors on N20's are usually screwed on simply, and can be swapped with other compatible motors. 

 

- Nigel

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2 hours ago, Nigelcliffe said:

 

Why the choice of 12v motor, given that N20's come with a range of motor voltages ?   By going for a lower voltage motor, you don't need the voltage multiplier circuitry.

The motors on N20's are usually screwed on simply, and can be swapped with other compatible motors. 

 

- Nigel

The 12V motor is already in stock so it might as well be used. The choice of using 12V circuitry was made when this was going to be a conversion using the Bachmann chassis and motor. This wasn't possible so I decided to use the Comet chassis instead.

 

I'm expecting that future projects will be 6V.

 

Cheers

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How are you getting the drive to the axle?   With the reduction in the gearbox mounted on the motor, you do not really need a worm drive and it's possible to use a crown wheel which is much more efficient.

 

Frank

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1 hour ago, fallen said:

How are you getting the drive to the axle?   With the reduction in the gearbox mounted on the motor, you do not really need a worm drive and it's possible to use a crown wheel which is much more efficient.

 

Frank

Bevel gears, now on their way from China! Bearing in mind the inefficiencies of worm/worm wheel I do wonder about the effect they would have on battery charge life.

Cheers

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I have a loco with an N20 motor and crown wheel drive.  I have noticed a little inertia just from the motor, no flywheel.  The loco does not stop dead when the throttle is closed, it runs on a little bit.  I have not got enough track (it's 3 mm scale, 14.2 mm gauge) to test the battery run-time yet.

 

Frank

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Having taken a look at the components I bought from Micron and compared them with Corbs' diagram, it's clear that I need to do some connecting of components using Molex PicoBlade  connectors and it seems I need both 2 & 4 pin m/f connectors. To do this I need a crimping tool and there is a bewildering variety on offer, see:

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=crimping+tool+for+Picoblade+1.25mm+&_sacat=0

and:

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=crimping+tools+for+Molex+Picoblade+connectors&_sacat=0

 

I'd be grateful for advice please

Cheers

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The few times I've used these, I've bought the solder type connectors that Micron sells, not the crimp type - for the sockets that is..... and the pre-wired leads with plugs. Mind you, I've not needed more that 2 pins.

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How good is your eyesight? I crimp these with a fine tipped pair of needle nose pliers. Its decidedly fiddly, and I use a magnifier. But if you only want to do a couple it will get you going.

Expect to waste a few on the way though. 

Sorry I cant help with the proper answer.

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2 hours ago, Giles said:

The few times I've used these, I've bought the solder type connectors that Micron sells, not the crimp type - for the sockets that is..... and the pre-wired leads with plugs. Mind you, I've not needed more that 2 pins.

Interesting! What type of connector do you normally use, please.

Cheers

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Molex Picoblade - here- just down a bit on this page....

 

http://www.micronradiocontrol.co.uk/conn_picoblade.html

 

Where space is less of an issue, I just buy pre wired plugs and sockets from eBay. They tend to be a little longer than the solder type, but in most instances I have room (just search 1.25mm connector)

 

Beet

Giles

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As an alternative to crimping them yourself, you can buy them with the wires already attached, which makes connecting up a lot easier.

 

Frank

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